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Polymer Chemistry
Guangxi University School of Chemistry & Chemical Engineerin
g
Li Guang Hua (李光华)
Lab:材料楼—409#,321# E-mail : [email protected] phone: 15978133590
CHAPTER 6
1. Introduction
Reactions of Vinyl Polymers :
2. Functional Group Reactions
3. Ring-Forming Reactions
4. Crosslinking
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4. Crosslinking
5. Block and Graft Copolymer Formation
6. Polymer Degradation
(1)
1. INTRODUCTION (I)
Monomer PZN Polymer 1
Polymer 2
Chemical reaction
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Polymer 2
Synthesize new polymers.
Endow new functionality to polymers.Chemical reaction
1. INTRODUCTION (II)
¹ Introduce cyclic unites into polymer backbone.
¹ Introduction or modification of functional groups.
Chemical modifications of vinyl polymers are grouped into five general categories:
Ø
DP unchanged
DP unchanged
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¹ Reactions leading to block and graft copolymers
¹ Crosslinking reactions
¹ Degradation reactions
DP unchanged
DP
DP
DP
1. INTRODUCTION (III)
Influence factors of polymer reactions :Ø
¹ Physical factors
¤ Crystallinity (%) of polymer
¤ Solubility of polymer
¤ Structure of polymer chain
Crystalline regionsAmorphous regions
Crosslinking or steric effects
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¹ Chemical factors
¤ Probability effect
CH2
CH
CH2
CH
CH2
CH
CH2
CH
CH2
CH
Cl Cl Cl Cl Cl
CH2
CH
CH2
CH
CH2
CH
CH2
CH
CH2
CH
Cl
Zn
1. INTRODUCTION (IV)
¤ Neighboring group effect
CH2C CH2CH
CH3
C CO O
O O
CH2C
CO
C
CHC
O O
H2CH3
+
O
NO2
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NO2
CH2C CH2CH
CH3
CO2 CO2
OH–
2. FUNCTIONAL GROUP REACTIONS (I)
Introduction of New Functional GroupsF
CH2CH2 n CHCH2
Cl n
Cl2
chlorination
Chlorinated PE (CPE)
á Increase flame resistance and solubility compared with PE
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CH2CH
SO2Cl n
CH2CH2 nCl2, SO2
chlorosulfonation
á Provide sites for subsequent crosslinking reaction
2. FUNCTIONAL GROUP REACTIONS (II)
CH2CH
C6H5 n
CF2CF
C6F11 n
F2
fluorination
á Enhance chemical inertness and improve solvent barrier
CH OCH Cl
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CH2CH
n
CH2CH
CH2Cl n
CH3OCH2ClAlCl3
Benzene ring : nitration, sulfonation, chloromethylation, etc.
2. FUNCTIONAL GROUP REACTIONS (III)
Conversion of Functional GroupsFSome polymers :
difficult or impossible to prepare by direct PZN
CH2CH
OCCH
CH2CH + CH3COOCH3CH3OH/KOH
Δ
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OCCH3
O n
OH nΔ
CH2 CH
OCOCH3
n
R· PZN
CH2 CH
OH
CH3CHOtautomer
×
Poly(vinyl alcohol) (PVA)
2. FUNCTIONAL GROUP REACTIONS (IV)
CH2C
CH3
C O
OSi(CH3)3 n
CH2C
CH3
CO2H n
1) H2O, OH–
2) H+
Isotactic or syndiotacticIsotactic or syndiotactic
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CH2 C
C O
OSi(CH3)3
CH3
n
R– PZN
CH2 C
COOH
CH3
× R· PZN
3. RING-FORMING REACTIONS (I)
Introduction of cyclic units into polymers :¹ Rigidity¹ Glass transition temperature (Tg)
¹ Thermal stability
EX.,
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Carbon fiberØ
Rayon fiberpyrolysis Carbon fiber (1870s by Edison)
1000~2000oC
PAN fiberpyrolysis
1000~2000oC
graphitization2500~2800oC
Graphite fiber(Carbon fiber)
C% : 85 ~ 99% (high strength)
C% > 99% (high modulus)
3. RING-FORMING REACTIONS (II)
C C CN NN N N N
Δ
Δ
Ladder –HCN
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N N N
H H H
Ladder graphite-type
polymer–HCN–N2
á High strength, high modulus, high thermal stability
Widely used in high performance composites
3. RING-FORMING REACTIONS (III)
4000 K Carbon nanotubeCarbon-arc furnace
á The nanotubes are much stronger than conventional graphite fibers, and hold promise of yielding composites with superior properties.
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diamond C60 (1985)
graphite (10, 10) tube (1991)
3. RING-FORMING REACTIONS (IV)
CH2CH
OH
CH2CH
OH
CH2CH
OH
OO
CH2
OHHCHO
H+
poly(vinyl formal)
“vinylon” (维尼龙)
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OH OHOH
OO
CH2
C3H7
OHC3H7CHO
H+
poly(vinyl butyral)
á Used as a plastic film in laminated safety glass
PVA
4. CROSSLINKING (I)
¹ Vulcanization (硫化,交联)
For the commercial standpoint, crosslinking is fundamental to the rubber and elastomer industries.
A general term applied to the crosslinking of polymers, particularly elastomers
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¹ Radiation crosslinking
¹ Photochemical crosslinking
¹ Crosslinking through labile functional groups
¹ Ionic crosslinking
Use peroxides, sulfur
VulcanizationF
4. CROSSLINKING (II)
CH2CH2RO +
CHCH2
CHCH2
+
CHCH2 + ROH
CHCH2
CHCH2
Ø
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CH2CH RO+CHCH2 + ROHCHCH CHCH2
CHCH CHCH2
CHCH CHCH2
+CHCH CHCH2
CHCH CHCH2
Ø
4. CROSSLINKING (III)
CHCH CHCH2
+CH2CH CHCH2
CHCH CHCH2CHCH CHCH2 +
CHCH CHCH2
CH2CH CHCH2
CH2CH CHCH2
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CH2CH CH2CH2
CHCH CHCH2 +
S8
CH2CH CHCH2
Sm
+ SnCH2CH CHCH2 + Sm Sn
δ δØ
4. CROSSLINKING (IV)
CH2CH CHCH2
CH2CH CHCH2
Sm
CH2CH CH2CH2
Sm
+ CHCH CHCH2S8
Sm
CHCH CHCH2
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CH2CH CHCH2
CHCH CHCH2
CH2CH CHCH2
SmCH2CH CHCH2
CHCH CHCH2
CH2CH CH2CH2
Sm
+
CHCH CHCH2
4. CROSSLINKING (V)
The rate of vulcanization with sulfur is slow.
¤ Accelerator :
[(CH3)2NCS ]2Zn2+
S S S
(CH3)2NCSSCN(CH3)2
Zinc dithiocarbamate tetramethylthiuram disulfide
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¤ Activator :
Zinc oxide; Stearic acid
二硫代氨基甲酸盐
4. CROSSLINKING (VI)
Radiation crosslinkingFRadiation : photons, electrons, neutrons, or protons
Crosslinking & degradation
¹ The doses of radiationHigh doses of radiation Degradation
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¹ Polymer structure (low doses of radiation)
¤ 1,1-disubstituted vinyl polymers Degradation
¤ Helogen-substituted vinyl polymers Loss of helogen
¤Most other vinyl polymers Crosslinking
CH2CH2
CH2CH2 + H(neighboring chain)
4. CROSSLINKING (VII)
+ HCHCH2radiation
+ H2CHCH2
For LDPE
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CHCH2
CHCH2
+CHCH2
CHCH2
CH2CH
R
CHCH
R
+ H CH CH + RH
4. CROSSLINKING (VIII)
Photochemical crosslinking (photocrosslinking)FUltraviolet or visible light-induced crosslinking
Ø Applications :
¹ Printed circuits for electronic equipment
¹ Printing inks
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¹ Printing inks¹ Coatings for optical fibers¹ Varnishes for paper and carbon board (复写纸)
¹ Finishes for vinyl flooring, wood, paper and metal
¹ Curing of dental materials
Surface treatment
Two basic methods of photocrosslinkingØ
¹ Incorporating photosensitizers into polymer
4. CROSSLINKING (IX)
C
O
benzophenone
hvC
O *
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benzophenoneCH2CH
R
C
OH
+CH2C
R
combination
Crosslinked polymer
4. CROSSLINKING (X)
CH2CHCH2CH
C O
R
C O
R
CH2CH2
C O
R
C OR
CH2 C+
CH2CHCH2CH2
C O RCO
+
hv
chromophore
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C O
RRC+
Crosslinked polymer
chromophore
4. CROSSLINKING (XI)
¹ Photocycloaddition
CH CHArOC
O
CHArCH CO
O
+OC
O
CO
O
Ar
Ar
hv
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+ hv
[2π+ 2π] cycloaddition
[4π+ 4π] cycloaddition
Crosslinking through labile functional groupsF
4. CROSSLINKING (XII)
CH SO2Cl2
CH
CH2
SO2NH
CH2
CHAr NHSO2H2N NH2Ar
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CH22
CH
CH2
SO2OROSO2
CH2
CHHO OHR
Ionic crosslinkingF
4. CROSSLINKING (XIII)
CH2CH
SO2Cl
CH2CH
SO2
CHCH2
O2SPb2+
PbO, H2O
polyelectrolyte
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CH2CH2
CH3
CO2H
CH2Cxy
ionomoer
Ca(OH)2CH2CH2
CH3
CO2
CH2Cxy
CH2CH2
CH3
CO2
CH2Cxy
Ca 2+Physical crosslinking
5. BLOCK & GRAFT COPOLYMER (I)
F Block copolymers
A B
Solution Solid State
Unique phase behavior
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Spheres gyroid lamellae cylinder(BCC) (hex)c ≥ cmc (Micelle)
volume fraction (f) of B block ↑
H2O 10 ~ 50 nm
Thermoplastic elastomers, plastic modifiers, adhesives,membranes, polymer blends, DDS, nanocomposites, etc.
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5. BLOCK & GRAFT COPOLYMER (I)
LiPSO
OCH3 PS-b-PMMA Li+ n-BuLiTHF-78oC
CH3OH
PS-b-PMMA
By anionic PZNØ
PS-b-PMMA
PIB PIB-b-PS+ coinitiator TiCl4
-80oC 2. CH3OH
1.
By cationic PZNØ
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By living radical PZNØ
5. BLOCK & GRAFT COPOLYMER (II)
CH3O
O
CH
CH3
BrC CH3O
O
CH
CH3
C CH2 C
CH3
C O
OCH3
Br
n
MMACuCl/bpy
PMMA macroinitiator
CH3O
O
CH
CH3
C CH2 C
CH3
C O
OCH3
Br
n
CH2 CH
C O
OCH3 m
MACuCl/bpy
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N C
CH3
CH3
CO
NH CH2 CH2 O
Cl
O2
Azo-alkyl halide
5. BLOCK & GRAFT COPOLYMER (III)
By difunctional initiatorsØ
Azo-alkyl halide
The othersØ
CHCH2OH
Ph
+ OCN CHCH2
Ph
OCNH
O
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5. BLOCK & GRAFT COPOLYMER (IV)
CH3
CH3
CHCH2OC
R CHCH3
CH3
CH3
CH3
CHCH2OC
R CCH3
CH3
OOH
O2
MΔ
CH3
CH3
CHCH2OC
R CCH3
CH3
O
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Graft copolymers F
5. BLOCK & GRAFT COPOLYMER (V)
Grafting fromØ
X
X
X
X
XnM
X = initiating group
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O
CH2CH
OCCH3
O
CH2CH
OCCH2(CH2CH2)x
O
CH2C
OCCH3
(CH2CH2)yCH2=CH2
peroxide
X = initiating group
CH2CH CH2CH
Ph
BF3OH+
OCH3
Grafting ontoØ
5. BLOCK & GRAFT COPOLYMER (VI)
CH2CH
OCH3
CH2CH
Ph
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O
N+ HO2C CNHCH2CH2OC
O O
Grafting throughØ
5. BLOCK & GRAFT COPOLYMER (VII)
+M Initiator
macromer ormacromonomer
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macromonomer
6. POLYMER DEGRADATION (I)
Degradation :Reduction of molecular weight
The mode of degradation¹ Depropagation or depolymerzation¹ Random chain scission¹ Elimination of side groups
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¹ Elimination of side groups
The methods of degrading polymers¹ Chemical degradation (chemical reagents: O2, H2O, etc.)¹ Thermal degradation (heat)¹ Radiation degradation (photons, protons, electrons, neutrons )¹ Ultrasonic or mechanical degradation¹ Microbiological degradation (microbe)
6. POLYMER DEGRADATION (II)
Chemical degradationFOxidationØ
CH2CHCH2CCH2CH
R RR
OOHCH2CHCH2
R RR
O+ CCH2CH + OH
Saturated polymer
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Saturated polymer
CH2 CH CH CH2O2 CH2 CH CH CH
OOH
CH2 CH CH CH2
O
+ OH
degradation & crosslinking
Unsaturated polymer
6. POLYMER DEGRADATION (III)
CH2 CH CH CH2O2
Unsaturated polymerCH2 CH CH CH2
O O
CH2 CH CH CH2
O O
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CH2CH O2
á Order of resistance to oxidation
CH2 C
CH3
CH3
n
CH2 CH2 n CH2 CH
CH3 n
CH2 CH CH CH2 n> > >
6. POLYMER DEGRADATION (IV)
Thermal degradationF
á The order of thermal stability of polyolefins
CH2 C
CH3
CH2 CH2 n CH2 CH> >
For C-C main chain
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CH2 C
CH3 n
CH2 CH2 n CH2 CH
CH3 n
> >
For C-H bond
CH3 CH2 CH C C CH2> > >
6. POLYMER DEGRADATION (V)
Thermal degradationF
O
CH2CH
OCCH3
n CH CH +
O
HOCCH3nΔ
¹ Elimination of side groups
PVAc
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PVAc
¹ Random chain scission
CH2CH2CH2CH2 CH2CH2 + CH2CH2
CH CH2 + CH3CH2
6. POLYMER DEGRADATION (VI)
¹ Depropagation or depolymerzation
CH2CCH2C
R
R
R
R
CH2C
R
+
R
CH2 CR
R
1,1-disubstituted polymer :
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PMMA
Poly(α-methyl styrene)
6. POLYMER DEGRADATION (VII)
Radiation degradationFRadiation : photons, electrons, neutrons, or protons
Crosslinking & degradation
CH2CCH2C
R RUVΔ
depolymerization
Ø
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CH2CCH2C
R RΔ
depolymerization
CH2CCH2C
R
R
R
RUVR.T.
Crosslinking & degradation
1,1-disubstituted polymer
POLYMER DEGRADATION (VIII)
Photodegrable plastics
Other vinyl polymers UV crosslinking
All vinyl polymers High dosage of radiation degradation
Ø
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COR
O
UVC
OR
+
O
+UV
H.W. : 1, 2, 4; 7, 10
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