Polymer Chemistry Li Gua Hua ( 李光华 ) Lab: 材料楼 409#,321# E-mail : lighua@gmail.com Cell phone: 15978133590 School of Chemistry & Chemical Eineerin g
CHAPTER 6 Reactions of Vinyl Polymers : 1. Introduction 2. Functional Group Reactions 3. Ri-Formi Reactions 4. Crosslinki 5. Block and Graft Copolymer Formation 6. Polymer Degradation (1) School of Chemistry & Chemical Eineeri
1. INTRDUCTIN (I) Monomer PZN Polymer 1 Polymer 2 Chemical reaction Chemical reaction Synthesize new polymers. Endow new functionality to polymers. (2) School of Chemistry & Chemical Eineeri
1. INTRDUCTIN (II) Chemical modifications of vinyl polymers are grouped into five general categories: Introductionormodification offunctionalgroups. DP unchaed Introduce cyclic unites into polymer backbone. DP unchaed Reactions leadi to block and graft copolymers DP Crosslinki reactions DP Degradation reactions DP (3) School of Chemistry & Chemical Eineeri
1. INTRDUCTIN (III) Influence factors of polymer reactions : Physicalfactors Structure of polymer chain Crystallinity (%) of polymer Solubility of polymer Crosslinki or steric effects Crystalline regions Amorphous regions Chemical factors Probability effect CH 2 CH 2 CH 2 CH 2 CH 2 CH CH CH CH CH Zn CH 2 CH 2 CH 2 CH 2 CH 2 CH CH CH CH CH Cl Cl Cl Cl Cl Cl (4) School of Chemistry & Chemical Eineeri
1. INTRDUCTIN (IV) Neighbori group effect CH 2 C C CH 2 CH C CH 2 C H 2 C CH C C + N 2 H N 2 CH 2 C CH 2 CH C 2 C 2 (5) School of Chemistry & Chemical Eineeri
2. FUNCTINAL GRUP REACTINS (I) F Introduction of New Functional Groups CH 2 CH 2 n Cl 2 chlorination CHCH 2 Cl Chlorinated PE (CPE) n Increase flame resistance and solubility compared with PE CH 2 CH 2 n Cl 2, S 2 chlorosulfonation CH 2 CH S 2 Cl n Provide sites for subsequent crosslinki reaction (6) School of Chemistry & Chemical Eineeri
2. FUNCTINAL GRUP REACTINS (II) CH 2 CH F 2 fluorination CF 2 CF C 6 H 5 n C 6 F 11 n Enhance chemical inertness and improve solvent barrier CH 2 CH CH 2 Cl AlCl 3 CH 2 CH n CH 2 Cl n Benzene ri : nitration, sulfonation, chloromethylation, etc. (7) School of Chemistry & Chemical Eineeri
2. FUNCTINAL GRUP REACTINS (III) F Conversion of Functional Groups Some polymers : difficult or impossible to prepare by direct PZN CH 2 CH C H/KH Δ CH 2 CH + C H n n Poly(vinyl alcohol) (PVA) R PZN nch 2 CH CH 2 CH tautomer CH C H (8) School of Chemistry & Chemical Eineeri
2. FUNCTINAL GRUP REACTINS (IV) CH 2 C C 1) H 2, H 2) H + CH 2 C C 2 H n Si( ) 3 Isotactic or syndiotactic n Isotactic or syndiotactic R PZN R PZN n CH 2 C CH 2 C CH C Si( ) 3 (9) School of Chemistry & Chemical Eineeri
3. RING-FRMING REACTINS (I) Introduction of cyclic units into polymers : Rigidity Glass transition temperature (T g ) Thermal stability EX., Carbon fiber Rayon fiber pyrolysis 1000~2000 o C Carbon fiber (1870s by Edison) C% : 85 ~ 99% (high streth) PAN fiber pyrolysis 1000~2000 o C graphitization 2500~2800 o C Graphite fiber (Carbon fiber) C% > 99% (high modulus) (10) School of Chemistry & Chemical Eineeri
3. RING-FRMING REACTINS (II) Δ C C C N N N N N N Δ Ladder graphite-type polymer HCN N 2 N N N H H H High streth, high modulus, high thermal stability Widely used in high performance composites (11) School of Chemistry & Chemical Eineeri
3. RING-FRMING REACTINS (III) Carbon-arcfurnace 4000 K Carbonnanotube The nanotubes are much stroer than conventional graphite fibers, and hold promise of yieldi composites with superior properties. diamond C 60 (1985) graphite (10, 10) tube (1991) (12) School of Chemistry & Chemical Eineeri
3. RING-FRMING REACTINS (IV) HCH H + CH 2 H poly(vinyl formal) CH 2 CH CH 2 CH CH 2 CH vinylon ( 维尼龙 ) H H H PVA C 3 H 7 CH CH 2 H + H C 3 H 7 poly(vinyl butyral) Used as a plastic film in laminated safety glass (13) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (I) For the commercial standpoint, crosslinki is fundamental to the rubber and elastomer industries. Vulcanization ( 硫化, 交联 ) A general term applied to the crosslinki of polymers, particularly elastomers Use peroxides, sulfur Radiation crosslinki Photochemical crosslinki Crosslinki through labile functional groups Ionic crosslinki (14) School of Chemistry & Chemical Eineeri
F Vulcanization 4. CRSSLINKING (II) R + CH 2 CH 2 CHCH 2 + RH CHCH 2 + CHCH 2 CHCH 2 CHCH 2 CH 2 CH CHCH 2 + R CHCH CHCH 2 + RH CHCH CHCH 2 + CHCH CHCH 2 CHCH CHCH 2 CHCH CHCH 2 (15) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (III) CHCH CHCH 2 + CH 2 CH CHCH 2 CHCH CHCH 2 CH 2 CH CHCH 2 CH 2 CH CHCH 2 CHCH CHCH 2 + CHCH CHCH 2 CH 2 CH CH 2 CH 2 S 8 δ δ CH 2 CH CHCH 2 + S m S n CH 2 CH CHCH 2 S m + S n (16) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (IV) CH 2 CH CHCH 2 S m CH 2 CH CHCH 2 CH 2 CH CH 2 CH 2 S m + CHCH CHCH 2 S 8 CHCH CHCH 2 S m CH 2 CH CHCH 2 CHCH CHCH 2 S m CH 2 CH CH 2 CH 2 + CHCH CHCH 2 CH 2 CH CHCH 2 CHCH CHCH 2 S m CH 2 CH CHCH 2 (17) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (V) The rate of vulcanization with sulfur is slow. Accelerator : S S S [( ) 2 NCS ] 2 Zn 2+ Zinc dithiocarbamate 二硫代氨基甲酸盐 ( ) 2 NCSSCN( ) 2 tetramethylthiuram disulfide Activator : Zinc oxide; Stearic acid (18) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (VI) F Radiation crosslinki Radiation : photons, electrons, neutrons, or protons Crosslinki & degradation The doses of radiation High doses of radiation Degradation Polymer structure (low doses of radiation) 1,1-disubstituted vinyl polymers Degradation Helogen-substituted vinyl polymers Loss of helogen Most other vinyl polymers Crosslinki (19) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (VII) For LDPE CH 2 CH 2 radiation CHCH 2 + H CH 2 CH 2 + H (neighbori chain) CHCH 2 + H 2 CHCH 2 + CHCH 2 CHCH 2 CHCH 2 CH 2 CH R CHCH R + H CH CH + RH (20) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (VIII) F Photochemical crosslinki (photocrosslinki) Ultraviolet or visible light-induced crosslinki Applications : Printed circuits for electronic equipment Printi inks Coatis for optical fibers Varnishes for paper and carbon board ( 复写纸 ) Finishes for vinyl floori, wood, paper and metal Curi of dental materials Surface treatment (21) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (IX) Two basic methods of photocrosslinki Incorporati photosensitizers into polymer C benzophenone hv * C CH 2 CH R H C + CH 2 C R combination Crosslinked polymer (22) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (X) CH 2 CH 2 + CH 2 C CH 2 CHCH 2 CH hv C R C R C C R R chromophore CH 2 CHCH 2 CH 2 C + RC R Crosslinked polymer (23) School of Chemistry & Chemical Eineeri
Photocycloaddition 4. CRSSLINKING (XI) C CH CHAr + hv C Ar ArCH CH C Ar C [2π+ 2π] cycloaddition + hv [4π+ 4π] cycloaddition (24) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (XII) F Crosslinki through labile functional groups H 2 N Ar NH 2 CH S 2 NH Ar NHS 2 CH CH 2 CH 2 2 CH CH 2 S 2 Cl H R H CH CH CH 2 S 2 RS 2 CH 2 (25) School of Chemistry & Chemical Eineeri
4. CRSSLINKING (XIII) F Ionic crosslinki CH 2 CH S 2 Cl Pb, H 2 CH 2 CH CHCH 2 S 2 Pb 2+ 2 S polyelectrolyte CH 2 CH 2 x CH 2 C C 2 H y Ca(H) 2 CH 2 CH 2 x CH 2 C C 2 y Physical crosslinki Ca 2+ CH 2 CH 2 C 2 x CH 2 C CH3 ionomoer y (26) School of Chemistry & Chemical Eineeri
5. BLCK & GRAFT CPLYMER (I) F Block copolymers A B Unique phase behavior Solution Solid State H 2 c cmc (Micelle) 10 ~ 50 nm Spheres gyroid lamellae cylinder (BCC) (hex) volume fraction (f) of B block Thermoplastic elastomers, plastic modifiers, adhesives, membranes, polymer blends, DDS, nanocomposites, etc. (27) School of Chemistry & Chemical Eineeri
5. BLCK & GRAFT CPLYMER (I) By anionic PZN + n-buli THF -78 o C PS Li PS-b-PMMA Li H PS-b-PMMA By cationic PZN + coinitiator TiCl 1. 4 PIB -80 o C 2. H PIB-b-PS (28) School of Chemistry & Chemical Eineeri
5. BLCK & GRAFT CPLYMER (II) By livi radical PZN C CH Br MMA CuCl/bpy C CH CH 2 C C Br PMMA macroinitiator n MA CuCl/bpy C CH CH 2 C CH 2 CH Br C C n m (29) School of Chemistry & Chemical Eineeri
5. BLCK & GRAFT CPLYMER (III) By difunctional initiators N C C NH CH 2 CH 2 Cl 2 Azo-alkyl halide The others CHCH 2 H Ph + CN CHCH 2 Ph CNH (30) School of Chemistry & Chemical Eineeri
5. BLCK & GRAFT CPLYMER (IV) CHCH 2 C R CH 2 CHCH 2 C R C H Δ M CHCH 2 C R C (31) School of Chemistry & Chemical Eineeri
5. BLCK & GRAFT CPLYMER (V) F Graft copolymers Grafti from X X X nm X X X = initiati group (CH 2 CH 2 ) y CH 2 CH CH 2 =CH 2 peroxide CH 2 CH CH 2 C C CCH 2 (CH 2 CH 2 ) x C (32) School of Chemistry & Chemical Eineeri
5. BLCK & GRAFT CPLYMER (VI) Grafti onto CH 2 CH BF 3 H CH 2 CH CH 2 CH Ph + CH 2 CH Ph N + H 2 C CNHCH 2 CH 2 C (33) School of Chemistry & Chemical Eineeri
5. BLCK & GRAFT CPLYMER (VII) Grafti through M + Initiator macromer or macromonomer (34) School of Chemistry & Chemical Eineeri
6. PLYMER DEGRADATIN (I) Degradation : Reduction of molecular weight The mode of degradation Depropagation or depolymerzation Random chain scission Elimination of side groups The methods of degradi polymers Chemical degradation (chemical reagents: 2, H 2, etc.) Thermal degradation (heat) Radiation degradation (photons, protons, electrons, neutrons ) Ultrasonic or mechanical degradation Microbiological degradation (microbe) (35) School of Chemistry & Chemical Eineeri
6. PLYMER DEGRADATIN (II) F Chemical degradation xidation H CH 2 CHCH 2 CCH 2 CH R R R Saturated polymer CH 2 CHCH 2 R + CCH 2 CH + H R R CH 2 CH CH CH 2 2 CH 2 CH CH CH Unsaturated polymer H CH 2 CH CH CH 2 + H degradation & crosslinki (36) School of Chemistry & Chemical Eineeri
6. PLYMER DEGRADATIN (III) CH 2 CH CH CH 2 2 Unsaturated polymer CH 2 CH CH CH 2 CH 2 CH CH CH 2 2 CH 2 CH rder of resistance to oxidation CH 2 C > CH 2 CH 2 n > CH 2 CH > CH 2 CH CH CH 2 n n n (37) School of Chemistry & Chemical Eineeri
6. PLYMER DEGRADATIN (IV) F Thermal degradation The order of thermal stability of polyolefins For C-C main chain > > CH 2 CH 2 n CH 2 CH CH 2 C n n For C-H bond > CH 2 > CH > C C CH 2 (38) School of Chemistry & Chemical Eineeri
6. PLYMER DEGRADATIN (V) F Thermal degradation Elimination of side groups Δ CH 2 CH n CH CH n + C PVAc HC Random chain scission CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 + CH 2 CH 2 CH CH 2 + CH 2 (39) School of Chemistry & Chemical Eineeri
6. PLYMER DEGRADATIN (VI) Depropagation or depolymerzation R R R CH 2 CCH 2 C CH 2 C + CH 2 C R R R R R 1,1-disubstituted polymer : PMMA Poly(α-methyl styrene) (40) School of Chemistry & Chemical Eineeri
6. PLYMER DEGRADATIN (VII) F Radiation degradation Radiation : photons, electrons, neutrons, or protons Crosslinki & degradation R R CH 2 CCH 2 C R R UV Δ 1,1-disubstituted polymer depolymerization R R CH 2 CCH 2 C R R UV R.T. Crosslinki & degradation (41) School of Chemistry & Chemical Eineeri
PLYMER DEGRADATIN (VIII) ther vinyl polymers UV crosslinki All vinyl polymers High dosage of radiation degradation Photodegrable plastics UV + R C R C UV + (42) School of Chemistry & Chemical Eineeri
H.W. : 1, 2, 4; 7, 10 (42) School of Chemistry & Chemical Eineeri