research article the effect of h-bonding on radical...

Hindawi Publishing CorporationInternational Journal of Polymer ScienceVolume 2013 Article ID 842894 9 pageshttpdxdoiorg1011552013842894

Research ArticleThe Effect of H-Bonding on Radical Copolymerization of MaleicAnhydride with N-tert-Butylacrylamide and Its Characterization

Ahmet Okudan and AyGe Karasakal

Department of Chemistry Selcuk University 42075 Konya Turkey

Correspondence should be addressed to Ahmet Okudan okudan1gmailcom

Received 31 July 2013 Revised 7 October 2013 Accepted 13 October 2013

Academic Editor Jose Ramon Leiza

Copyright copy 2013 A Okudan and A KarasakalThis is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in anymedium provided the originalwork is properly cited

The copolymerization reaction between N-tert-butylacrylamide (NTBA) and maleic anhydride (MA) in p-dioxane solution at65∘C using 221015840-azoisobutyronitrile (AIBN) as an initiator in nitrogen atmosphere was carried out The chemical structure ofthe obtained copolymers from a wide range of monomer feeds was determined by elemental analysis (content of N for NTBAunits) Fourier transform infrared (FTIR) and 1H-NMR spectroscopy Also the amounts of MA units in the copolymers werefound using the chemical titration method An observed tendency toward alternating copolymerization at le50 mol NTBAconcentration in monomer feed and relatively high activity of NTBA growing radical was explained by H-bond formation betweenC=O (anhydride) and NH (amide) fragments during chain growth reactions Intrinsic viscosity and the molecular weights of thesynthesized copolymers depend on the type of comonomer and the amount of NTBA units in the copolymers The synthesizedpoly(NTBA-MA)s containing a functional amphiphilic group show both temperature and pH sensitivity and can be used forbiological proposes as a physiologically active macromolecular system

1 Introduction

Copolymer is the most successful and powerful method foreffecting a systematic change in polymer [1] Studies haveshown that the copolymerization reactions provide anexcellent way to prepare macromolecules with specificchemical structures and to control properties such ashydrophilichydrophobic balances polarity and solubility[2] Many polymers with reactive functional groups are nowbeing synthesized tested and used not only for the macro-molecular properties but also for the properties of functionalgroups These functional groups provide an approach to asubsequent modification of the polymers for a specific endapplication [3] An anhydride group containing maleic anhy-dride and its polymers has received considerable attentionrecently because of its varied applications Maleic anhydridecannot be homopolymerized under normal conditions [4] orhardly homopropagates whichmeans thatmaleic anhydride-maleic anhydride diads are virtually absent in the polymerchain [5] Nevertheless the reactive MA moiety providesthe copolymers with a wide variety of options for chemical

modification [6] Furthermore it is generally accepted thatcopolymerization shows a strong tendency toward alterna-tion [7] Acrylamide and its derivatives can undergo alternat-ing copolymerization with maleic anhydride under the givenconditions [8ndash18] Due to this complex formation the alter-nating copolymerization of the monomers can be initiatedby a free radical mechanismThe reaction products are alter-nating copolymers providing high polarity and mechanicaland thermal stability [19] In this study MA which containstwo adjacent carboxylic acid groups in anhydride form andreactive carbonyl groups that may be subjected to numerousreactions was selected for polymerizations with NTBA

Hydrogen bonding is one of the important noncovalentinteractions in nature The bonding energies for normalhydrogen bonds are between 10ndash50 kJmol These stable anddynamic molecular complexes can be prepared by simplemolecular self-assembly processes using such hydrogen [20]For design of synthetic polymers hydrogen bonding has notbeen considered to be very useful If varieties of hydrogenbonding moieties are strategically introduced into syntheticpolymeric and organic materials new polymeric materials

2 International Journal of Polymer Science

exhibiting a variety of functions can be obtained Peculiaritiesof H-complex formation in the monomer-monomer andmonomer-solvent systems give the opportunity to design newpolyfunctional co- and terpolymers [21]

The reactivemaleic anhydridemoiety provides the copol-ymers with a wide variety of options for chemical modifi-cation Depending on the requirement many of the maleicanhydride copolymers can be modified by a reaction at themaleic anhydride ring [22 23] Those copolymers are poten-tially useful as flocculants for purification of industrial wastewater and as coatings formicrocapsule production and paperdry-strength agents [14] Also these functional amphiphiliccopolymers containing anion- and cation-active groups showboth temperature and pH sensitivity and can be used forbiological purposes as physiologically active macromolecularsystems Alternating copolymers of maleic anhydride can beregarded as preactivated polymers due to the presence ofanhydride moieties susceptible to the reaction with a pri-mary amine of a biomolecule [24] Numerous water-solublepolymers for the most part acrylic derivatives and vinyl typepolymers have been investigated for use as macromoleculardrug carriers [25] protein hybrids [26] and advanced appli-cations in biotechnology [6] Also in Trivedi and Cul-bertson [14] maleic anhydride copolymers are used formany purposes according to a detailed summary of theirapplication Recently the synthesis and characterization ofcationic stimuli-responsive containing acrylamide deriva-tives as potentially useful as carriers for gene delivery conju-gates of polyacrylamide derivatives with amino acids as prod-ings and antitumor active binary and ternary copolymers ofmaleic anhydride and acrylic acid (or 23-dihydropyran) havebeen reported [27 28]

This study has investigated the results of the synthesis andcharacterization of poly(NTBA-co-MA)s with different com-positions by the radical-initiated solution copolymerizationof NTBA and MA in a wide range of monomer ratios as away to obtain new reactive amphiphilic polymers that arepotentially useful as carriers for gene delivery The effect ofH-bond formation in between the ndashC=O groups of maleicanhydride with ndashNH groups of the N-tert-butyl acrylamideon the copolymer composition-properties relationship hasbeen described and discussed The synthesized copolymerswere characterized by IR-spectroscopy 1H-NMR elementalanalysis gel permeation chromatography (GPC) and chem-ical titration

2 Experimental Section

21 Materials Maleic anhydride (MA) (Fluka) was purifiedby recrystallization from anhydrous benzene and by sublima-tion in vacuo mp = 528∘C N-tert-butylacrylamide (NTBA)(Aldrich) was recrystallized in warm dry benzene 221015840-Azoisobutyronitrile (AIBN) (Fluka) was twice recrystallizedfrom methanol mp = 1025∘C p-Dioxane (Merck) wasrefluxed over sodium and distilled from aluminum lithiumhydride The middle fraction was used All other reagentswere used without further purification

22 NTBA-MA Copolymer

221 Synthesis of NTBA-MA Copolymer For the synthesisof an NTBA-MA copolymer various molar ratios of NTBAandMAwere dissolved in p-dioxane in a round-bottom flaskequipped with a magnetic stir bar and in a thermostatedsilicon oil bath at 65 plusmn 01∘C and a nitrogen inlet Reac-tion conditions are [M]total = 133molL [AIBN] = 66 times10minus4molL and monomer ratios of [NTBA][MA] = 043 minus233 The balance amount of NTBA was introduced in fourdoses after every 45 minutes Each dosing was accompaniedby degassing with nitrogen for 5 minutes The polymeriza-tion was continued for approximately 24 hours After thepolymerizations were completed the NTBA-MA copolymerswere separated from the reaction mixture by precipitation indiethyl ether which was a solvent for these two monomersand the NTBA homopolymer at room temperature Theproducts were obtained as white powder Then the productsobtained were redissolved in p-dioxane and reprecipitated bydiethyl ether andwashed several times with diethyl etherTheinsoluble copolymer was removed by filtration and dried ina vacuum oven at 50∘C for at least 2 days Monomer unitratio119898

11198982= 476 524 content of N = 652 (by elemental

analysis) acid number 412mg KOHg [120578]in = 0097 gdL inTHF at 25 plusmn 01∘CM

119899= 6100 (by GPC)

222 The Determination of Monomer Reactivity Ratios Tothe determine the monomer reactivity ratios the copoly-merization of NTBA with MA using various monomer feedratios was carried out in p-dioxane by free radical copolymer-ization in the presence of AIBN as an initiator in nitrogeninlet To determine monomer reactivity ratios NTBA-MAcopolymers were synthesized in glass ampoules sealed withrubber septa using p-dioxane as a solvent and AIBN as aninitiator The total monomer and initiator concentrationswere kept at 133molL and 66 times 10minus4molL respectivelyDissolved oxygen was removed from the reaction solutionby nitrogen purging for 30 minutes before immersion in awater bath at 65∘C plusmn 01∘CThe copolymerization system washomogeneous in all the cases investigated After a specificlength of time each ampoule was removed from the waterbath and the reaction was stopped with 05mL of a 10wtsolution of hydroquinone in p-dioxane The polymerizationwas continued for approximately 3 hours Diethyl ether wasused to isolate the copolymers All samples were purified byreprecipitation using p-dioxane as the solvent and diethylether as the precipitant and then dried in a vacuum oven at50∘C for at least 2 days

23 Copolymer Characterization The copolymer composi-tions were found by elemental (N content for NTBA units)and chemical (acid number for anhydride units) FTIR and 1HNMR spectroscopy using an integral area of chemical shifts ofmonomer functional groups for quantitative analysis

The absorption value ratios between characteristic analyt-ical bands of 1658 cmminus1 (for band in NTBA unit) 1775 cmminus1(for C=Oband inMAunit) and the least changing absorptionband of 1365 cmminus1 as a standard band (119860 = log(119868119868

119900)

International Journal of Polymer Science 3

Δ119860119894

= 119860119894

1198601365) were used to calculate the copolymer com-

position Molar fractions (in mol) of comonomer units (1198981

and1198982) in copolymer using FTIR analysis data are calculated

according to following equation

1198981

1198982

= (Δ1198601198981658

1

Δ1198601198981775

2

) times (1198721

1198722

) (1)

where1198721and119872

2are molecular weights of NTBA and MA

monomer units respectivelyThe compositions of the copolymers synthesized were

determined by comparing the integrals of the tert-butyl andmethyne group regions in the spectra ofNTBA andMAunitsrespectivelyThemolar fractions of the comonomer units (119898

1

and 1198982) in NTBA-MA copolymers using 1H NMR analysis

data were calculated according to the following equations

1198601198981(CH3)

119860 total=

11989911198981

(11988611198981+ 11988721198982)

1198601198982(CH) = 119860 total =

11989921198982

(11988611198981+ 11988721198982)

(2)

where 1198601198981and 119860119898

2are the normalized areas per 119867 from

the corresponding functional groups of the monomer unitregions in 1H NMR spectra 119860 total is the total area of protonsin the copolymer 119899

1and 1198992are the integers of proton(s) in the

functional group of the monomers 119886 and 119887 are the integers ofprotons in the monomer units (119898

1and 119898

2) in the case of

(1198981+ 1198982) = 1 monomer unit ratios can be calculated from

(2) using the following simplified form

1198981

1198982

= 119891 =

11989921198601198981(CH3)

11989911198601198982(CH or CH3)

(3)

The CHNS-932 Model LECO Elemental Analyzer wasused for the determination of C H and N contents inthe copolymers synthesized Molar fractions (mol) ofcomonomer units (119898

1and 119898

2) in NTBA-MA copolymers

using elemental analysis data (content of N) were calculatedaccording to the following equation

1198981=

1198722

[(119860N119861) minus Δ119872 times 10minus2

] (4)

where1198722is themolecularweight ofMAunits119860N is the atom

weight of N 119861 is the content of N in the copolymers ()Δ119872 = 119872

1minus 1198722(1198721is the molecular weight of the NTBA

unit)Fourier transform infrared spectroscopy FTIR (Perkin

Elmer 100 spectrometer) was used to determine the copoly-mer composition using either solid films or mull samplesin the 4000ndash600 cmminus1 range where 30 scans were taken at4 cmminus1 resolution The mulls were prepared by mixing thepolymerwith dryKBr powder and pressing into a transparentKBr pellet Solid films were prepared by solution casting thepolymer onto a KBr pellet followed by evaporation of thesolvent1H NMR spectra were recorded on a Varian 400 NMR

spectrometer with DMSO-d6as a solvent at 50∘C Samples

for 1HNMR spectroscopy were prepared by dissolving about30mg of products in 1mL dimethyl sulfoxide-d

6 Tetram-

ethylsilane was used as an internal referenceThe molecular weights (Mn and Mw) and the disper-

sity index (MwMn) of the copolymers were determinedby Gel-Permeation Chromatography using a Shimpack 804column with THF as a mobile phase-eluent at a flow rateof 10mLmin at 35∘C Standard polystyrene was used formolecular weight calibration

Acid numbers (AN) of the anhydride-containing copoly-mers were determined by standard titration method [29 30]

AN(mg KOH

g) =

ml KOH timesN KOH times 5611

g polymer

MA () = AN times 98

2 times 561

(5)

The unit viscosity factor was determined by viscosimet-ric method For viscosimetric characterization solutions ofall samples in THF with a molarity of 01ndash10 gdL wereprepared The time flow of the solutions and solvents wasrecorded by Ubbelohde type viscosimeter placed in a ther-mostatic water bath at 25 plusmn 01

∘C Specific viscosity (120578sp)and relative viscosity (119899

119903) were calculated ((6) and (7)) By

using these values with Solomon-Ciuta equation (8) intrinsicviscosity [120578] was calculated

119899119903=119905

119905119900

(6)

where 119905119900is flow time of solvent 119905 is flow time of solution

120578sp = 120578119903 minus 1 (7)

[120578] =1414

119862(120578sp minus ln 120578

119903)12

(8)

where [120578] is intrinsic viscosity 119862 is the molarity of thesolution

3 Results and Discussion

31 Synthesis of the NTBA-MA Copolymer The synthesis ofthe copolymer of NTBA and MA was carried out in bothfour steps and in one step adding NTBA using AIBN as aninitiator at 65∘C in a different monomer ratio (NTBAMA)In the four steps of polymerization the dosing of the morereactivemonomerNTBAwas regulated to obtain copolymersof controlled composition The monomer NTBA was intro-duced in four equal doses over a time period of 2 hours and15 minutes at the beginning of the reaction The copolymercomposition and nitrogen content are given in Table 1 Thepolymerization reaction is shown in Scheme 1

The effects of various parameters such as the feed molratio (NTBAMA) amount of AIBN reaction temperatureand reaction time were determined Also Table 2 gives theintrinsic viscosities [120578] molecular weights (M

119899) polydisper-

sity index (PDI) conversion and acid numbers (AN) forthe NTBA-MA copolymer Adding four steps to the reactionmedium of NTBA gave better results than adding one step(Table 2)


Table 1 1H NMR FTIR and elemental analysis of NTBAMA copolymers synthesized from various monomers feed ratio

Feed mol ratioNTBAMA

A1198981(NTBA)a

A1198982(MA)a

Δ1198601

b

1658 cmminus1integral area

Δ1198602

b


Copolymer composition (mol) FTIR analysis1H NMR analysis Nitrogen analysis

1198601198981(NTBA) 119860119898

2(MA) 1198981

1198982

1198981

1198982

1198981

1198982

7030 0065 0054 0510 0280 665 335 658 342 661 3396040 0048 0042 0468 0312 584 416 608 392 592 4085050 0056 0047 0487 0455 551 449 545 455 541 4594060 0034 0030 0405 0587 502 498 488 512 487 5133070 0023 0024 0355 0865 476 524 466 534 468 532aIntegral area for CH chemical shift of NTBA (terbutyl group) and MA anhydride (methyne group) unitsbThe values of Δ119860

1= 0178 and Δ119860

2= 0275 for poly (NTBA) and poly (MA) respectively 1365 cmminus1 is used as a less changed standard band

Table 2 The effect on copolymerization of reaction conditions

RunFeed mol ratioNTBAMA

AIBN( mol)

Temperature(∘C)

Time(h)

119872119899

(gmol) 120578 (gdL) PDI Acid number(mgKOHg)

Ncontent()

Conversion()

1a 7030 10 65 24 2800 0063 109 285 854 332a 6040 10 65 24 3100 0069 110 305 801 493a 5050 10 65 24 3400 0073 110 354 746 914a 4060 10 65 24 4000 0081 111 378 687 1465a 3070 10 65 24 6100 0097 112 412 652 3416a 3070 03 65 24 6300 0098 115 381 076 437a 3070 07 65 24 6200 0096 113 390 154 868a 3070 14 65 24 5000 0092 112 378 685 3889a 3070 10 65 6 4800 0091 111 362 269 15110a 3070 10 65 3 4500 0087 112 344 147 8311a 3070 10 80 24 6000 0096 116 384 603 34012a 3070 10 50 24 4800 0092 111 372 356 20813b 3070 10 65 3 4200 0083 111 322 123 7214b 3070 10 65 24 5900 0095 111 378 417 244aNTBA added in four portions bNTBA added at once

C ON H

CO

COO

C ON H

CO

CO O

n65∘C AIBN 24h+

Scheme 1 Polymerization reaction of NTBA-MA

32 H-Bonding Effect in Radical Copolymerization H-bonding as a variety of intermolecular interaction exertionessentially influenced the kinetic and elementary actions ofradical polymerization [13] H-bond is formed due to bothelectrostatic [31] and donor-acceptor interactions in H-complexes [32] Despite that considerable contribution of anelectrostatic interaction to energy of H-bond role of chargetransfer (donor-acceptor interaction) which is reasonable forchange of electron state and reactivity of individual compo-nents of monomerH-complex system is highly essential [21]

These directional interactions can be expressed as ndashX HndashY H (XY = NO ) stable and dynamic molecular com-plexes can be prepared by simple molecular self-assemblyprocesses using nucleic acids proteins and polysaccharideshaving hydrogen bonding groups which participate in theformation of supramolecular structures and the induction offunction [21] In these system anomaly high shifts and broadof H-bond in IR spectra and its high chemical shifts of theproton in NMR spectra were observed [21] The ther-modynamic peculiarities of H-complex formation in themonomer-monomer and monomer-solvent systems weredescribed by Kabanov et al [9] The determination of self-association and interassociation equilibrium constants of H-bond formation has been discussed in detail by Colemanand Painter [33] according to the authors H-bonds arecontinually breaking and reforming under the influenceof thermal motion and at any instant there is a distributionof species consisting of free monomers (non-hydrogen-bonded) hydrogen bonded dimers and hydrogen bonded


R

O NH OO OR

O OO NHNH

OO O

n

O

O

+

middot

middot

Scheme 2 The effect of H-bonding on copolymerization

O NH

OO O

OO O

OHN

Scheme 3

multimersThis distribution is affected by changes in temper-ature and concentration The effect of H-complex in radicalalternating copolymerization of MA and fumaric acid (FA)with acrylic acid (AA) was observed by ElrsquoSaied et al [34]They showed that copolymerization of these monomer pairsproceeds through formation of MA AA and FA AA H-complexes (ndashC=O HOndash) and it is possible to direct up pro-cesses away from the formation of alternating copolymers tothe formation of random copolymers with different compo-sitions by using naphthalene as an electron donor substancethat forms a donor-acceptor complex with a double bond ofacceptor MA In this study when examining the nature ofthe conjugation between functional groups and double bonds(C=O of amide and anhydride) NTBA and MA monomerscan be considered electron acceptors However this doesnot prevent the monomers from having sufficient activity infree-radical copolymerization of NTBA-MA monomer pairsthanks to the interaction between functional groups of thecomonomers or macroradicals through H-bonding [11 1226] This effect can be illustrated as is shown in Schemes 2and 3

Copolymerizations were carried out to low conversions(le10) in order to determine monomer reactivity ratios inthe steady-state kinetics by using the known terminal modelof the Kelen-Tudos (KT) equation [35]

120578 = (1199031+ 1199032

120572) 120585 minus

1199032

120572 (9)

where 120578 = [119865(119891 minus 1)119891](1198652

119891 + 120572) 120585 = (1198652

119891)(1198652

119891 +

120572) 120572 (arbitrary constant) = (1198652

119891)min(1198652

119891)max 119865 =

[NTBA][MA] and 119891 = (11989811198982)

000

005

010

015

020

025

030

035

040

00 02 04 06 08 10minus005

minus010

minus015

120585

120578

Figure 1 KT plots for the copolymerization of NTBA-MA using◼1H NMR and ∙ elemental analysis data Slope = 119903

1

+ 1199032

120572 andintercept minus119903

2

120572

Results of FTIR analysis of copolymers prepared usingdifferent monomer feed ratios are illustrated in Figure 3 Onthe basis of these data the values of absorption bands forthe comonomers units are calculated and are used for thedetermination of copolymer composition according to (1)

The results of 1H NMR and elemental analysis of vari-ous initial monomer ratios of copolymer are illustrated inFigure 4 and summarized in Table 1 Copolymer composi-tions calculated using elemental analysis data (contents of Nwere in very good agreement with those obtained from 1HNMR analysis using (3) and (4) For comparison a nonlinearregression (NLR) procedure using amicrocomputer program[36] has also been applied to recalculate copolymeriza-tion constants Table 3 shows that the copolymerization ofmonomers in NTBA-MA system has a tendency towardalternation especially at NTBA le 50mol

33 Structural Analysis of the NTBA-MA Copolymer An ele-mental analysis determined the carbon hydrogen and nitro-gen content of theNTBA-MAcopolymerThepolymerizationratio of the monomer and the content of the amine group inthe copolymer were calculated from the carbon and nitrogencontent of the copolymer The results shown in Table 1indicate that the amine group content in the copolymerslightly increased the monomer molar ratio in the copolymerand greatly increased with the growth of the monomer ratioNTBAMA The effect of the monomer ratio on the growthof the amine group content due to the probability of theNTBA self-polymerization increased with enlargement of themonomer ratio NTBAMA

Tables 1 and 2 indicate that the molecular weight of theNTBA-MA copolymer depended on the monomer ratioNTBAMA and the molecular weight of the NTBA-MAcopolymer greatly increased with the decrease of the mon-omer ratio NTBAMA (up to NTBAMA 3070) The resultsindicate that a significant change in the amount of conversionand molecular weight has been observed with increasing theamount of MA (Table 2) For the system of the NTBA-MA


Table 3 Kelen-Tudos (KT) parameters for determination of monomer reactivity ratios for NTBA-MA pair

Monomer ratioNTBAMA By 1H NMR Parameters of KT equation By N analysis Parameters of KT equation Mean sequence lengtha

119865 119891 1198652

119891 + 120572b

120578 120585 119891 1198652

119891 + 120572b

120578 120585 1205831

1205832

235 211 336 033 079 205 342 033 080 191 104153 143 230 024 070 151 210 027 068 170 105100 130 142 018 055 140 143 019 052 164 105066 112 108 010 037 113 110 008 035 151 106040 094 091 minus001 018 100 090 002 020 144 107Rection conditions solvent 119901-dioxane [119872] total = 133molL [AIBN] = 66 times 10minus4molL 65 plusmn 01 ∘C conversion le 10aThese values were calculated by using the following 119903

1and 1199032values 044 and 007 for NTBA-MA pair

b120572 (arbitrary constant) = 068 by elemental analysis

Table 4 The values copolymerization (1199031

and 1199032

) for NTBA (1198721

)-MA (119872

2

) monomer pair determining by KT and NLR methodsusing 1H NMR and elemental analysis techniques

Copolymer Methods 1199031

1199032

NTBA-MA 1H NMR analysis (KT) 043 011NTBA-MA NLR 045 013NTBA-MA Elemental analysis (KT) 046 007NTBA-MA NLR 046 0068

copolymerization the NTBA and MA easily copolymerizedbut the self-polymerization of NTBA is easier than the copol-ymerization of NTBA-MA and the self-polymerization ofMA happens with difficultly

As shown in Table 2 the optimum reaction conditionsare as follows feed mol ratio NTBAMA is 3070 (molmol)the amount of AIBN is 1 mol at 65∘C of temperature and24 hours of time under reflux A considerable increase inconversion was observed when increasing the amount ofAIBN initiator However the results indicate that a loweramount of initiator which depends on the amount of AIBNis desired to promote the molecular weight Under optimumreaction conditions acid number is increased to 412mgKOHg (Run 5 Table 2) Lowering the reaction temperaturedecreased the copolymerization conversion and molecularweight Likewise lowering the reaction time significantlydecreased the copolymerization conversion and molecularweight Adding four steps to the reaction medium of NTBAthe more reactive monomer gave better results than addingone step In the same reaction conditions conversion isincreased from 244 to 341 and likewise molecularweight is increased from 5900 gmol to 6100 gmol (Runs 5and 14 Table 2) Under optimum reaction conditions ele-mental analysis acid numbers and GPC results were deter-mined as molecular weight of 6100 gmol and conversion341

Monomer reactivity ratios (1199031and 119903

2) were evaluated

using experimental data presented in Tables 1 and 3 fromKTplots of 120585 versus 120578 (Figure 1) and NLR analysis As evidencedfrom the values which are summarized inTable 4 alternatingcopolymerizations are realized in monomer systems with ahighly visibly degree of alternation of monomer units in the

NTBA-MA system Copolymerization constants determinedby KT method and calculated by NLR method have similarvalues indicating good agreement between both FTIR and 1HNMR analysis techniques (Tables 3 and 4) As an additionalconformation of the alternating tendency of themonomers inthe systems studied the monomer sequence lengths (120583

1and

1205832) are calculated from well-known equations [37]

1205831= 1 + 119903

1(1198981

1198982

)

1205832= 1 + 119903

2(1198982

1198981

)

(10)

Table 3 presents the values of 1205831and 120583

2 As seen from the

values for different monomer-copolymer compositions thevalue of120583

1(NTBAunit sequence length) visibly changes from

144 to 191 in the NTBA-MA systems in increasing NTBAfeed concentration Meanwhile the mean unit sequencelengths for MA anhydride units (120583

2) have relatively low and

nearly unchanged values This fact is correlated with the lowvalues of 119903

2and confirms the alternating tendency of the

copolymer (Table 4)In general these results allow us to assume that the chain

growth reactions proceed predominantly by the addition ofanhydride comonomers to simNTBA∙ macroradical throughthe intermediate formation of an H-bond between secondaryamide and anhydride carbonyl groups according to Scheme 2

The parameters of specific activity (1198761) and polarity (119890

1)

for the NTBA monomer were calculated using the 119876-119890 valuereported by Alfrey and Price [38] in the form of the followingequations

1198902= 1198901plusmn (minus ln 119903

11199032)

1198761= (

1198762

1199032

) exp [minus1198901(1198901minus 1198902)]

(11)

Using the known values of 1198762= 023 and 119890

2= 225 for the

MA comonomer [39] the parameters of 1198761= 028 and

1198901= minus069 have been calculated for NTBA which describe

the energy of localization order and120587-electron density of theNTBA double bond


T(

)T(

)T(

)

(a)

(b)

(c)

4000

3500

3000

2500

2000

1500

1000 500

450

(cmminus1)

1854

17751658

15551265 1222

1170

Figure 2 Fragments of FTIR spectra of the MA (a) NTBA (b) and poly(NTBA-co-MA) (c)

2000 1500

18541775 1658

(a)

(b)

(c)

(d)

(e)

Figure 3 FTIR spectra of the poly(NTBA-co-MA)s preparing indifferent monomer feed NTBA MA 70 30 (a) 60 40 (b) 50 50(c) 40 60 (d) and 30 70 (e)

331 FT-IRAnalysis Figure 2 shows the FTIR spectra ofMANTBA and Poly(NTBA-MA) The NTBA-MA copolymerspectra display the characteristic absorption bands at1658 cmminus1 (119899 C=O amide I) at 1555 cmminus1 (NndashH bendingamide II) at about 1265 cmminus1 (trans-amide III) 3400ndash3100 cmminus1 broad band for NH secondary amide and the bandcould be assigned to H-bonded NH mainly to the C=O ofthe MA unit The band assigned to the tertiary butyl groups[ndashC(CH

3)3] at 1222 cmminus1 [40ndash42] The absorption region

between 2860 and 2973 cmminus1 corresponds to ndashCH stretchingvibrations of ndashCH

3and ndashCH

2-groups [43 44] The MA

spectra display characteristic absorption bands at 1854ndash1775 cmminus1 corresponding to C=O stretching of anhydridegroup and 1170 cmminus1 broad CndashOndashC anhydride [11]

It can be proposed that intermolecular H-bonded frag-ments are most probably formed between alternating NTBA-MA diads of macromolecules as follows

Figure 3 illustrates the structure composition relationshipfor NTBA-MA copolymer

An increase in the quantity of MA in the NTBA-MAcopolymers was observed An increased intensity of thepeaks at 1854ndash1775 cmminus1 corresponds to C=O stretching ofanhydride group Also the increasing quantity NTBA wasobserved in the increased intensity of the peaks at 1658 cmminus1corresponding to C=O amide I (Figure 3)

332 1H NMR Analysis Supporting evidence for the struc-tural elucidation is revealed by 1HNMR analysis Character-istic peaks (1H NMR spectra (in DMSO-d

6at 50∘C) ppm

(1) 9H CH313 (2) 2H CH

216 (3) 1H CH 24 (5) 1H NH

78 for NTPA unit (4) 2H CH 35 for maleic unit in Figure 4)can be identified in the 1HNMRspectra of the copolymer andused as analytical signals for quantitative analysis of polymercomposition Figure 4 shows the 1H NMR spectra of NTBA-MA copolymer and Figure 5 shows the 1H NMR spectra ofPolyNTBA

4 Conclusion

Poly(NTBA-co-MA)s are synthesized by the radical copoly-merization method in the chosen conditions which areconsidered in Section 2The compositions of prepared copol-ymers using a wide range of monomer feed were determinedby the elemental nitrogen analysis of NTBA monomerunits containing N atoms In addition this study used theFourier transform infrared (FTIR) and 1H NMR analysismethods to evaluate some structural peculiarities of synthe-sized copolymers and determine copolymer compositionsThe relatively high activity of the pair monomers studiedhaving a tendency toward alternating copolymerization wasexplained by the effect of H-bond formation between C=O


O

O OO

C

C C 1

234

5

11

1

23 4

5N HDMSO

102

222

112

209

1028

(ppm)100 50 00

Figure 4 1H NMR spectra of poly(NTBA-co-MA) in DMSO-d6

at50∘C

CDCl3

100 50 00(ppm)

Figure 5 1H NMR spectra of poly-NTBA in CDCl3

at 27∘C

(anhydride) and NH (amide) groups during chain growthreactionsThe formation of alternating copolymers predom-inantly at le50mol of NTBA in the monomer feedwas confirmed by the results of copolymer composition-property relationship studies Synthesized and characterizednew amphiphilic copolymers can be used as macromoleculardrug carries and advanced applications in biotechnology

Acknowledgment

The authors thank Selcuk University Research Project Fund(SUBAP 12201027) for support of this work

References

[1] D A Tirrell M H Tirrell N M Bikalws et al Encyclopedia ofPolymers Sciences and Engineering vol 4 John Wiley amp SonsNew York NY USA 1985

[2] A Gallardo A R Lemus J San Roman A Cifuentes and J-CDıez-Masa ldquoMicellar electrokinetic chromatography applied tocopolymer systems with heterogeneous distributionrdquo Macro-molecules vol 32 no 3 pp 610ndash617 1999

[3] O Vogl A C Albertsson and Z Janovic ldquoNew developmentsin speciality polymers polymeric stabilizersrdquo Polymer vol 26no 9 pp 1288ndash1296 1985

[4] J M G Cowie Alternating Copolymers Plenum Press NewYork NY USA 1985

[5] D J T Hill J H OrsquoDonnell and P W OrsquoSullivan ldquoAnalysis ofthe mechanism of copolymerization of styrene and maleicanhydriderdquoMacromolecules vol 18 pp 9ndash17 1985

[6] B Klumperman ldquoMechanistic considerations on styrene-maleic anhydride copolymerization reactionsrdquo Polymer Chem-istry vol 1 no 5 pp 558ndash562 2010

[7] E Tsuchida and T Tomono ldquoMechanism of alternating copoly-merization of styrene and maleic anhydriderdquo MacromolocularChemistry vol 141 pp 265ndash298 1971

[8] Z M O Rzaev Polymers and Copolymers of Maleic Anhydridevol 102 of Chemical Abstracts Elm Baku Azerbaijan 1985

[9] V A Kabanov V P Zubov and Y Semchikov Complex RadicalPolymerization Khimiya Moscow Russia 1987

[10] Z M O Rzaev ldquoComplex-radical alternating copolymeriza-tionrdquo Progress in Polymer Science vol 25 no 2 pp 163ndash2172000

[11] S Dincer V Koseli H Kesim Z M O Rzaev and E PiskinldquoRadical copolymerization of N-isopropylacrylamide withanhydrides of maleic and citraconic acidsrdquo European PolymerJournal vol 38 no 11 pp 2143ndash2152 2002

[12] S Dincer Z M O Rzaev and E Piskin ldquoSynthesis and charac-terization of stimuli-responsive poly(N-isopropylacrylamide-co-N-vinyl-2-pyrrolidone)rdquo Journal of Polymer Research vol 13no 2 pp 121ndash131 2006

[13] H K Can Z M O Rzaev and A Guner ldquoH-bonding effectin radical terpolymerization of maleic anhydride acrylic acid(methyl acrylate) and vinyl acetaterdquoHacettepe Journal of Biologyand Chemistry vol 40 pp 427ndash443 2012

[14] B C Trivedi and B M CulbertsonMaleic Anhydride PlenumPress New York NY USA 1982

[15] H Ringsdorf J Venzmer and F M Winnik ldquoFluorescencestudies of hydrophobically modified poly(N-isopropylacryl-amides)rdquoMacromolecules vol 24 no 7 pp 1678ndash1686 1991

[16] J-P Chen and M-S Hsu ldquoPreparations and propertiesof temperature-sensitive poly(N-isopropylacrylamide)-chym-otrypsin conjugatesrdquo Journal of Molecular Catalysis B vol 2 no4-5 pp 233ndash241 1997

[17] C K Chee S Rimmer I Soutar and L Swanson ldquoTime-resolved fluorescence anisotropy studies of the temperature-induced intramolecular conformational transition of poly(N-isopropylacrylamide) in dilute aqueous solutionrdquo Polymer vol38 no 2 pp 483ndash486 1997

[18] H G Schild and D A Tirrell ldquoUse of nonradiative energytransfer to explore interpolymer and polymer-solute interac-tions in aqueous solutions of poly(N-isopropylacrylamide)rdquoMacromolecules vol 25 no 18 pp 4553ndash4558 1992

[19] A Reiche A Weinkauf B Sandner F Rittig and G FleischerldquoAlternating copolymers for novel polymer electrolytes theelectrochemical propertiesrdquo Electrochimica Acta vol 45 no 8pp 1327ndash1334 2000

[20] T Kato N Mizoshita and K Kanie ldquohydrogen-bonded liquidcrystalline materials supramolecular polymeric assembly and


the induction of dynamic functionrdquo Macromolecular RapidCommunication vol 22 pp 797ndash814 2001

[21] H K Can Z M O Rzaev and A Guner ldquoHydrogen (H)-complex formation of maleic anhydride-acrylic acid (methylacrylate) monomer systemrdquo Journal of Molecular Liquids vol111 no 1ndash3 pp 77ndash84 2004

[22] C Ladaviere T Delair A Domard C Pichot and B Man-drand ldquoStudies of the thermal stability of maleic anhydrideco-polymers in aqueous solutionrdquo Polymer Degradation andStability vol 65 no 2 pp 231ndash241 1999

[23] R K Bund and R S Singhal ldquoAn alkali stable cellulase bychemical modification using maleic anhydriderdquo CarbohydratePolymers vol 47 no 2 pp 137ndash141 2002

[24] L Veron M-C de Bignicourt T Delair C Pichot and BMandrand ldquoSyntheses of poly[N-(22 dimethoxyethyl)-N-methyl acrylamide] for the immobilization of oligonucleotidesrdquoJournal of Applied Polymer Science vol 60 no 2 pp 235ndash2441996

[25] N-J Lee Y-A Kim S-H Kim W-M Choi and W-J CholdquoSyntheses and biological activities ofN-alaninylmaleimide andits polymersrdquo Journal of Macromolecular Science A vol 34 no1 pp 1ndash11 1997

[26] N PDesai and J AHubbell ldquoSolution technique to incorporatepolyethylene oxide and other water-soluble polymers intosurfaces of polymeric biomaterialsrdquo Biomaterials vol 12 no 2pp 144ndash153 1991

[27] S Dincer A Tuncel and E Piskin ldquoA potential gene deliveryvector N-isopropylacrylamide-ethyleneimine block copoly-mersrdquo Macromolecular Chemistry and Physics vol 203 pp1460ndash1465 2002

[28] V Bulmus S Patr S A Tuncel and E Piskin ldquoStimuli-responsive properties of conjugates of N-isopropylacrylamide-co-acrylic acid oligomers with alanine glycine and serinemono- di- and tri-peptidesrdquo Journal of Controlled Release vol76 no 3 pp 265ndash274 2001

[29] B Kyu Kim S Yun Park and S Jin Park ldquoMorphological ther-mal and rheological properties of blends Polyethylenenylon-6polyethylenenylon-6(maleic anhydride-g-polyethylene) and(maleic anhydride-g-polyethylene)nylon-6rdquo European Poly-mer Journal vol 27 no 4-5 pp 349ndash354 1991

[30] C A Lucchesi P J Secrets and C F Hirn Standart Methodof Chemical Analysis Krieger Publishing Company New YorkNY USA 1975

[31] G A Jeffrey An Introduction to Hydrogen Bonding OxfordUniversity Press New York NY USA 1997

[32] P V Shibaev S L Jensen P Andersen et al ldquoMulticomponenthydrogen-bonded liquid crystalline mixturesrdquoMacromolecularRapid Communications vol 22 pp 493ndash497 2001

[33] M M Coleman and P C Painter ldquoHydrogen bonded polymerblendsrdquo Progress in Polymer Science vol 20 no 1 pp 1ndash59 1995

[34] A A ElrsquoSaied S Y Mirlina and V A Kargin ldquoCopolymeriza-tion of unsaturated mono- and dibasic acids The possibility ofcontrolling copolymer compositionrdquo Polymer Science USSRvol 11 no 2 pp 314ndash328 1969

[35] T Kelen and F Tudos ldquoAnalysis of the linear methods for deter-mining copolymerization reactivity ratios I A new improvedlinear graphic methodrdquo Journal of Macromolecular ScienceChemistry A vol 9 pp 1ndash27 1975

[36] M Dube R A Sanayei A Penlidis K F OrsquoDriscoll and P MReilly ldquoAmicrocomputer program for estimation of copolymer-ization reactivity ratiosrdquo Journal of Polymer Science A vol 29no 5 pp 703ndash708 1991

[37] C W Pyun ldquoComonomer and sterosequence distributions inhigh polymersrdquo Journal of Polymer Science A vol 8 no 7 pp1111ndash1126 1970

[38] T Alfrey and C C Price ldquoRelative reactivities in vinyl copoly-merizationrdquo Journal of Polymer Science vol 2 pp 101ndash106 1947

[39] L J Young and G Ham High PolymersmdashCopolymerizationInterscience New York NY USA 1964

[40] V Ozturk and O Okay ldquoTemperature sensitive poly (N-t-butylacrylamide-co-acrylamide) hydrogels synthesis andswelling behaviorrdquo Polymer vol 43 no 18 pp 5017ndash5026 2002

[41] V Bulmus S Patır S A Tuncel et al ldquoConjugates of poly(N-isopropyl acryl amide-co-acrylic acid) with alanine mono- di-and tri-peptidesrdquo Journal of Applied Polymer Science vol 88 pp2012ndash2019 2003

[42] N S Save M Jassal and A K Agrawal ldquoStimuli sensitivecopolymer poly(N-tert-butylacrylamideran-acrylamide) syn-thesis and characterizationrdquo Journal of Applied Polymer Sciencevol 95 no 3 pp 672ndash680 2005

[43] P Bajaj T V Sreekumar and K Sen ldquoEffect of reactionmediumon radical copolymerization of acrylonitrile with vinyl acidsrdquoJournal of Applied Polymer Science vol 79 pp 1640ndash1652 2001

[44] A K Bajpai and A Giri ldquoSwelling dynamics of a macromolec-ular hydrophilic network and evaluation of its potential forcontrolled release of agrochemicalsrdquo Reactive and FunctionalPolymers vol 53 no 2-3 pp 125ndash141 2002

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


exhibiting a variety of functions can be obtained Peculiaritiesof H-complex formation in the monomer-monomer andmonomer-solvent systems give the opportunity to design newpolyfunctional co- and terpolymers [21]

The reactivemaleic anhydridemoiety provides the copol-ymers with a wide variety of options for chemical modifi-cation Depending on the requirement many of the maleicanhydride copolymers can be modified by a reaction at themaleic anhydride ring [22 23] Those copolymers are poten-tially useful as flocculants for purification of industrial wastewater and as coatings formicrocapsule production and paperdry-strength agents [14] Also these functional amphiphiliccopolymers containing anion- and cation-active groups showboth temperature and pH sensitivity and can be used forbiological purposes as physiologically active macromolecularsystems Alternating copolymers of maleic anhydride can beregarded as preactivated polymers due to the presence ofanhydride moieties susceptible to the reaction with a pri-mary amine of a biomolecule [24] Numerous water-solublepolymers for the most part acrylic derivatives and vinyl typepolymers have been investigated for use as macromoleculardrug carriers [25] protein hybrids [26] and advanced appli-cations in biotechnology [6] Also in Trivedi and Cul-bertson [14] maleic anhydride copolymers are used formany purposes according to a detailed summary of theirapplication Recently the synthesis and characterization ofcationic stimuli-responsive containing acrylamide deriva-tives as potentially useful as carriers for gene delivery conju-gates of polyacrylamide derivatives with amino acids as prod-ings and antitumor active binary and ternary copolymers ofmaleic anhydride and acrylic acid (or 23-dihydropyran) havebeen reported [27 28]

This study has investigated the results of the synthesis andcharacterization of poly(NTBA-co-MA)s with different com-positions by the radical-initiated solution copolymerizationof NTBA and MA in a wide range of monomer ratios as away to obtain new reactive amphiphilic polymers that arepotentially useful as carriers for gene delivery The effect ofH-bond formation in between the ndashC=O groups of maleicanhydride with ndashNH groups of the N-tert-butyl acrylamideon the copolymer composition-properties relationship hasbeen described and discussed The synthesized copolymerswere characterized by IR-spectroscopy 1H-NMR elementalanalysis gel permeation chromatography (GPC) and chem-ical titration

2 Experimental Section

21 Materials Maleic anhydride (MA) (Fluka) was purifiedby recrystallization from anhydrous benzene and by sublima-tion in vacuo mp = 528∘C N-tert-butylacrylamide (NTBA)(Aldrich) was recrystallized in warm dry benzene 221015840-Azoisobutyronitrile (AIBN) (Fluka) was twice recrystallizedfrom methanol mp = 1025∘C p-Dioxane (Merck) wasrefluxed over sodium and distilled from aluminum lithiumhydride The middle fraction was used All other reagentswere used without further purification

22 NTBA-MA Copolymer

221 Synthesis of NTBA-MA Copolymer For the synthesisof an NTBA-MA copolymer various molar ratios of NTBAandMAwere dissolved in p-dioxane in a round-bottom flaskequipped with a magnetic stir bar and in a thermostatedsilicon oil bath at 65 plusmn 01∘C and a nitrogen inlet Reac-tion conditions are [M]total = 133molL [AIBN] = 66 times10minus4molL and monomer ratios of [NTBA][MA] = 043 minus233 The balance amount of NTBA was introduced in fourdoses after every 45 minutes Each dosing was accompaniedby degassing with nitrogen for 5 minutes The polymeriza-tion was continued for approximately 24 hours After thepolymerizations were completed the NTBA-MA copolymerswere separated from the reaction mixture by precipitation indiethyl ether which was a solvent for these two monomersand the NTBA homopolymer at room temperature Theproducts were obtained as white powder Then the productsobtained were redissolved in p-dioxane and reprecipitated bydiethyl ether andwashed several times with diethyl etherTheinsoluble copolymer was removed by filtration and dried ina vacuum oven at 50∘C for at least 2 days Monomer unitratio119898

11198982= 476 524 content of N = 652 (by elemental

analysis) acid number 412mg KOHg [120578]in = 0097 gdL inTHF at 25 plusmn 01∘CM

119899= 6100 (by GPC)

222 The Determination of Monomer Reactivity Ratios Tothe determine the monomer reactivity ratios the copoly-merization of NTBA with MA using various monomer feedratios was carried out in p-dioxane by free radical copolymer-ization in the presence of AIBN as an initiator in nitrogeninlet To determine monomer reactivity ratios NTBA-MAcopolymers were synthesized in glass ampoules sealed withrubber septa using p-dioxane as a solvent and AIBN as aninitiator The total monomer and initiator concentrationswere kept at 133molL and 66 times 10minus4molL respectivelyDissolved oxygen was removed from the reaction solutionby nitrogen purging for 30 minutes before immersion in awater bath at 65∘C plusmn 01∘CThe copolymerization system washomogeneous in all the cases investigated After a specificlength of time each ampoule was removed from the waterbath and the reaction was stopped with 05mL of a 10wtsolution of hydroquinone in p-dioxane The polymerizationwas continued for approximately 3 hours Diethyl ether wasused to isolate the copolymers All samples were purified byreprecipitation using p-dioxane as the solvent and diethylether as the precipitant and then dried in a vacuum oven at50∘C for at least 2 days

23 Copolymer Characterization The copolymer composi-tions were found by elemental (N content for NTBA units)and chemical (acid number for anhydride units) FTIR and 1HNMR spectroscopy using an integral area of chemical shifts ofmonomer functional groups for quantitative analysis

The absorption value ratios between characteristic analyt-ical bands of 1658 cmminus1 (for band in NTBA unit) 1775 cmminus1(for C=Oband inMAunit) and the least changing absorptionband of 1365 cmminus1 as a standard band (119860 = log(119868119868

119900)


Δ119860119894

= 119860119894





1198981

1198982

= (Δ1198601198981658

1

Δ1198601198981775

2

) times (1198721

1198722

) (1)

where1198721and119872




1



1198601198981(CH3)

119860 total=

11989911198981

(11988611198981+ 11988721198982)

1198601198982(CH) = 119860 total =

11989921198982

(11988611198981+ 11988721198982)

(2)

where 1198601198981and 119860119898





1and 119898

2) in the case of



1198981

1198982

= 119891 =

11989921198601198981(CH3)

11989911198601198982(CH or CH3)

(3)


1and 119898



1198981=

1198722


] (4)








6 Tetram-




AN(mg KOH

g) =


g polymer

MA () = AN times 98

2 times 561

(5)





119899119903=119905

119905119900

(6)


120578sp = 120578119903 minus 1 (7)

[120578] =1414

119862(120578sp minus ln 120578

119903)12

(8)





119899) polydisper-





A1198981(NTBA)a

A1198982(MA)a

Δ1198601

b


Δ1198602

b



1198601198981(NTBA) 119860119898

2(MA) 1198981

1198982

1198981

1198982

1198981

1198982


1= 0178 and Δ119860




AIBN( mol)

Temperature(∘C)

Time(h)

119872119899


Ncontent()

Conversion()


C ON H

CO

COO

C ON H

CO

CO O

n65∘C AIBN 24h+





R

O NH OO OR

O OO NHNH

OO O

n

O

O

+

middot

middot


O NH

OO O

OO O

OHN

Scheme 3



120578 = (1199031+ 1199032

120572) 120585 minus

1199032

120572 (9)

where 120578 = [119865(119891 minus 1)119891](1198652

119891 + 120572) 120585 = (1198652

119891)(1198652

119891 +


119891)min(1198652

119891)max 119865 =

[NTBA][MA] and 119891 = (11989811198982)

000

005

010

015

020

025

030

035

040

00 02 04 06 08 10minus005

minus010

minus015

120585

120578


1

+ 1199032


2

120572








119865 119891 1198652

119891 + 120572b

120578 120585 119891 1198652

119891 + 120572b

120578 120585 1205831

1205832





and 1199032

) for NTBA (1198721

)-MA (119872

2



1199032





2) were evaluated



1and


1205831= 1 + 119903

1(1198981

1198982

)

1205832= 1 + 119903

2(1198982

1198981

)

(10)


2 As seen from the










1)


1198902= 1198901plusmn (minus ln 119903

11199032)

1198761= (

1198762

1199032

) exp [minus1198901(1198901minus 1198902)]

(11)


2= 225 for the





T(

)T(

)T(

)

(a)

(b)

(c)

4000

3500

3000

2500

2000

1500

1000 500

450

(cmminus1)

1854

17751658

15551265 1222

1170


2000 1500

18541775 1658

(a)

(b)

(c)

(d)

(e)





3and ndashCH







6at 50∘C) ppm

(1) 9H CH313 (2) 2H CH

216 (3) 1H CH 24 (5) 1H NH


4 Conclusion



O

O OO

C

C C 1

234

5

11

1

23 4

5N HDMSO

102

222

112

209

1028

(ppm)100 50 00


at50∘C

CDCl3

100 50 00(ppm)


at 27∘C


Acknowledgment


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Δ119860119894

= 119860119894





1198981

1198982

= (Δ1198601198981658

1

Δ1198601198981775

2

) times (1198721

1198722

) (1)

where1198721and119872




1



1198601198981(CH3)

119860 total=

11989911198981

(11988611198981+ 11988721198982)

1198601198982(CH) = 119860 total =

11989921198982

(11988611198981+ 11988721198982)

(2)

where 1198601198981and 119860119898





1and 119898

2) in the case of



1198981

1198982

= 119891 =

11989921198601198981(CH3)

11989911198601198982(CH or CH3)

(3)


1and 119898



1198981=

1198722


] (4)








6 Tetram-




AN(mg KOH

g) =


g polymer

MA () = AN times 98

2 times 561

(5)





119899119903=119905

119905119900

(6)


120578sp = 120578119903 minus 1 (7)

[120578] =1414

119862(120578sp minus ln 120578

119903)12

(8)





119899) polydisper-





A1198981(NTBA)a

A1198982(MA)a

Δ1198601

b


Δ1198602

b



1198601198981(NTBA) 119860119898

2(MA) 1198981

1198982

1198981

1198982

1198981

1198982


1= 0178 and Δ119860




AIBN( mol)

Temperature(∘C)

Time(h)

119872119899


Ncontent()

Conversion()


C ON H

CO

COO

C ON H

CO

CO O

n65∘C AIBN 24h+





R

O NH OO OR

O OO NHNH

OO O

n

O

O

+

middot

middot


O NH

OO O

OO O

OHN

Scheme 3



120578 = (1199031+ 1199032

120572) 120585 minus

1199032

120572 (9)

where 120578 = [119865(119891 minus 1)119891](1198652

119891 + 120572) 120585 = (1198652

119891)(1198652

119891 +


119891)min(1198652

119891)max 119865 =

[NTBA][MA] and 119891 = (11989811198982)

000

005

010

015

020

025

030

035

040

00 02 04 06 08 10minus005

minus010

minus015

120585

120578


1

+ 1199032


2

120572








119865 119891 1198652

119891 + 120572b

120578 120585 119891 1198652

119891 + 120572b

120578 120585 1205831

1205832





and 1199032

) for NTBA (1198721

)-MA (119872

2



1199032





2) were evaluated



1and


1205831= 1 + 119903

1(1198981

1198982

)

1205832= 1 + 119903

2(1198982

1198981

)

(10)


2 As seen from the










1)


1198902= 1198901plusmn (minus ln 119903

11199032)

1198761= (

1198762

1199032

) exp [minus1198901(1198901minus 1198902)]

(11)


2= 225 for the





T(

)T(

)T(

)

(a)

(b)

(c)

4000

3500

3000

2500

2000

1500

1000 500

450

(cmminus1)

1854

17751658

15551265 1222

1170


2000 1500

18541775 1658

(a)

(b)

(c)

(d)

(e)





3and ndashCH







6at 50∘C) ppm

(1) 9H CH313 (2) 2H CH

216 (3) 1H CH 24 (5) 1H NH


4 Conclusion



O

O OO

C

C C 1

234

5

11

1

23 4

5N HDMSO

102

222

112

209

1028

(ppm)100 50 00


at50∘C

CDCl3

100 50 00(ppm)


at 27∘C


Acknowledgment


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






A1198981(NTBA)a

A1198982(MA)a

Δ1198601

b


Δ1198602

b



1198601198981(NTBA) 119860119898

2(MA) 1198981

1198982

1198981

1198982

1198981

1198982


1= 0178 and Δ119860




AIBN( mol)

Temperature(∘C)

Time(h)

119872119899


Ncontent()

Conversion()


C ON H

CO

COO

C ON H

CO

CO O

n65∘C AIBN 24h+





R

O NH OO OR

O OO NHNH

OO O

n

O

O

+

middot

middot


O NH

OO O

OO O

OHN

Scheme 3



120578 = (1199031+ 1199032

120572) 120585 minus

1199032

120572 (9)

where 120578 = [119865(119891 minus 1)119891](1198652

119891 + 120572) 120585 = (1198652

119891)(1198652

119891 +


119891)min(1198652

119891)max 119865 =

[NTBA][MA] and 119891 = (11989811198982)

000

005

010

015

020

025

030

035

040

00 02 04 06 08 10minus005

minus010

minus015

120585

120578


1

+ 1199032


2

120572








119865 119891 1198652

119891 + 120572b

120578 120585 119891 1198652

119891 + 120572b

120578 120585 1205831

1205832





and 1199032

) for NTBA (1198721

)-MA (119872

2



1199032





2) were evaluated



1and


1205831= 1 + 119903

1(1198981

1198982

)

1205832= 1 + 119903

2(1198982

1198981

)

(10)


2 As seen from the










1)


1198902= 1198901plusmn (minus ln 119903

11199032)

1198761= (

1198762

1199032

) exp [minus1198901(1198901minus 1198902)]

(11)


2= 225 for the





T(

)T(

)T(

)

(a)

(b)

(c)

4000

3500

3000

2500

2000

1500

1000 500

450

(cmminus1)

1854

17751658

15551265 1222

1170


2000 1500

18541775 1658

(a)

(b)

(c)

(d)

(e)





3and ndashCH







6at 50∘C) ppm

(1) 9H CH313 (2) 2H CH

216 (3) 1H CH 24 (5) 1H NH


4 Conclusion



O

O OO

C

C C 1

234

5

11

1

23 4

5N HDMSO

102

222

112

209

1028

(ppm)100 50 00


at50∘C

CDCl3

100 50 00(ppm)


at 27∘C


Acknowledgment


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




R

O NH OO OR

O OO NHNH

OO O

n

O

O

+

middot

middot


O NH

OO O

OO O

OHN

Scheme 3



120578 = (1199031+ 1199032

120572) 120585 minus

1199032

120572 (9)

where 120578 = [119865(119891 minus 1)119891](1198652

119891 + 120572) 120585 = (1198652

119891)(1198652

119891 +


119891)min(1198652

119891)max 119865 =

[NTBA][MA] and 119891 = (11989811198982)

000

005

010

015

020

025

030

035

040

00 02 04 06 08 10minus005

minus010

minus015

120585

120578


1

+ 1199032


2

120572








119865 119891 1198652

119891 + 120572b

120578 120585 119891 1198652

119891 + 120572b

120578 120585 1205831

1205832





and 1199032

) for NTBA (1198721

)-MA (119872

2



1199032





2) were evaluated



1and


1205831= 1 + 119903

1(1198981

1198982

)

1205832= 1 + 119903

2(1198982

1198981

)

(10)


2 As seen from the










1)


1198902= 1198901plusmn (minus ln 119903

11199032)

1198761= (

1198762

1199032

) exp [minus1198901(1198901minus 1198902)]

(11)


2= 225 for the





T(

)T(

)T(

)

(a)

(b)

(c)

4000

3500

3000

2500

2000

1500

1000 500

450

(cmminus1)

1854

17751658

15551265 1222

1170


2000 1500

18541775 1658

(a)

(b)

(c)

(d)

(e)





3and ndashCH







6at 50∘C) ppm

(1) 9H CH313 (2) 2H CH

216 (3) 1H CH 24 (5) 1H NH


4 Conclusion



O

O OO

C

C C 1

234

5

11

1

23 4

5N HDMSO

102

222

112

209

1028

(ppm)100 50 00


at50∘C

CDCl3

100 50 00(ppm)


at 27∘C


Acknowledgment


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






119865 119891 1198652

119891 + 120572b

120578 120585 119891 1198652

119891 + 120572b

120578 120585 1205831

1205832





and 1199032

) for NTBA (1198721

)-MA (119872

2



1199032





2) were evaluated



1and


1205831= 1 + 119903

1(1198981

1198982

)

1205832= 1 + 119903

2(1198982

1198981

)

(10)


2 As seen from the










1)


1198902= 1198901plusmn (minus ln 119903

11199032)

1198761= (

1198762

1199032

) exp [minus1198901(1198901minus 1198902)]

(11)


2= 225 for the





T(

)T(

)T(

)

(a)

(b)

(c)

4000

3500

3000

2500

2000

1500

1000 500

450

(cmminus1)

1854

17751658

15551265 1222

1170


2000 1500

18541775 1658

(a)

(b)

(c)

(d)

(e)





3and ndashCH







6at 50∘C) ppm

(1) 9H CH313 (2) 2H CH

216 (3) 1H CH 24 (5) 1H NH


4 Conclusion



O

O OO

C

C C 1

234

5

11

1

23 4

5N HDMSO

102

222

112

209

1028

(ppm)100 50 00


at50∘C

CDCl3

100 50 00(ppm)


at 27∘C


Acknowledgment


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




T(

)T(

)T(

)

(a)

(b)

(c)

4000

3500

3000

2500

2000

1500

1000 500

450

(cmminus1)

1854

17751658

15551265 1222

1170


2000 1500

18541775 1658

(a)

(b)

(c)

(d)

(e)





3and ndashCH







6at 50∘C) ppm

(1) 9H CH313 (2) 2H CH

216 (3) 1H CH 24 (5) 1H NH


4 Conclusion



O

O OO

C

C C 1

234

5

11

1

23 4

5N HDMSO

102

222

112

209

1028

(ppm)100 50 00


at50∘C

CDCl3

100 50 00(ppm)


at 27∘C


Acknowledgment


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




O

O OO

C

C C 1

234

5

11

1

23 4

5N HDMSO

102

222

112

209

1028

(ppm)100 50 00


at50∘C

CDCl3

100 50 00(ppm)


at 27∘C


Acknowledgment


References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article the effect of h-bonding on radical...

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