1

Synthesis of alternating hyperbranched copolymers using photofunctional inimer via living

radical mechanism

Ali DURAN POLYMER TECHNOLOGY

2

EXPERIMENTAL1. COPOLYMERIZATION DTCS was synthesized by the reaction of CMS with N,N-

diethyldithiocarbamate sodium salt in acetone, Photo-copolymerizations in acetone solution of DTCS with

MA were carried out by irradiation with UV light for 0.75-1.5 h in a sealed glass ampoule under high vacuum at 200C,

After polymerization, the polymer was recovered by precipitation in acetone/n-hexane mixture,

The solvents used in these copolymerizations (acetone and n-hexane) were distilled over calcium hydride,

DTCS: diethylaminodithiocarbamoylmethylstyrene,

CMS : chloromethylstyrene,

DTCS: diethylaminodithiocarbamoylmethylstyrene,

CMS : chloromethylstyrene,

3

EXPERIMENTAL2. CHARACTERIZATION OF COPOLYMERS In order to evaluate the reactivity ratios (r1 and r2), the

composition of hyperbranched copolymers was determined by FT-IR spectroscopy,

Calibration curve was constructed using the mixture of hyperbranched homopolymer of DTCS and MA,

Two monomers, M1 and M2, are defined as the inimer DTCS and MA , respectively,

The reactivity ratios, r1 and r2 were estimated by the curve-fitting procedure,

1H NMR spectra of hyperbranched copolymers were taken in CDCL3,

CDCL3 : deuteriated trichloro methane,

MA : maleic anhydride,

CDCL3 : deuteriated trichloro methane,

MA : maleic anhydride,

4

RESULTS AND DISCUSSION Photolysis of C1 leads to the initiating

benzyl radical with a less reactive DC radical that undergoes primary radical termination,

This benzyl radical can add to vinyl groups of a second molecule of C1 to produce dimer C2,

Dimer C2 corresponds to an AB2 monomer with two initiating / propogating sites,

By repeating these elementary reactions, this polymerization system proceeds to form alternating hyperbranched copolymers,

5

RESULTS AND DISCUSSION

Spectrum showed the expected absorbance for carbonyl group (1860 and 1760 cm-1 ),

Aromatic ring (1600 and 840 cm-1 ), Characteristic absorbance for DTCS

(1720 and 1500 cm-1 ), Extremely small quantities of MA

absorbance were observed around 3500 cm-1 , due to ring opening of MA,

6

RESULTS AND DISCUSSION

In order to determine the composition of the copolymers, the calibration curve was constructed using the mixture of hyperbranched homopolymer of DTCS and MA,

Fig. 2 shows the calibration curve, where OD and HPS indicate the optical density and hyperbranched homopolymer of DTCS, respectively,

Each copolymer composition F1 could be calculated using this calibration,

7

RESULTS AND DISCUSSION The observed values are fitted on the

solid line regardless of the variation of comonomer feed composition,

The dotted line indicates the curve for model compounds of styrene and MA,

Photo-copolymerization reactivity of DTCS and MA shows strong alternation,

The propogating copolymer radicals proceed always with homopolymerization of 1:1 complexes formed between the donor and acceptor monomers,

8

RESULTS AND DISCUSSION

Spectrum shows the expected resonance for the aromatic protons of polystyrenes (d and e ; 6.7-7.7 ppm ),

The methylene protons (g ;3.7 and 4.0 ppm) of the DC groups,

The methylene protons adjacent to DC groups (f ;4.5 ppm),

The broad signals from 1.4 to 3.5 ppm are assignable to CH (b and c) and CH2 (a) protons of the main chain,

The methyl protons (h ;1.2 ppm) of the DC groups are overlapped with signal a,

9

RESULTS AND DISCUSSION

The growth of the hyperbranched macromolecule is governed by the relative rate of reaction at either benzyl or phenethyl-like radical,

When considering the ideal statistics of chain growth of DTCS/MA complex, assuming equal reactivity constants for over radicals, f to g ratio should equal to 1:4,

The observed ratios f;g were in the range of 1:2.5 - 1:3,

This result means that the structures of the macromolecules were not perfectly dendritic but contained a respectable amount of lineer units.