暨南大学：《高分子化学》课程教学资源（PPT课件）第四章 离子型聚合 §4.2 阴离子聚合续 Anionic polymerization

review Finish the following reactions: BF+ HO CI HC=C Sncl4+RCI

BF3 + H2 O SnCl 4+ RCl Finish the following reactions: H2 C C CH3 CH3

§42 Anionic polymerizationction (1)History 1877, Wurtz, bases, epoxy ethane 1914, Na, Bd, Ip, st 1940, Ellis, BuLi, ethylene 1952, Higginson, styrene, KNH2, kinetic study 1956, Szwarc, sodium naphthalene, St, living polymerization conception 60s, commercial SDs products were available 90s, study on the living polymerization of polar monomers (2) Carbanion

§4.2 Anionic polymerization 1、Introduction 1877，Wurtz, bases, epoxy ethane 1914, Na, Bd, Ip, St 1940, Ellis, BuLi, ethylene 1952，Higginson, styrene, KNH2 , kinetic study 1956，Szwarc, sodium naphthalene, St, living polymerization conception 60's, commercial SDS products were available 90‘s, study on the living polymerization of polar monomers (1) History (2) Carbanion

2. Monomer (1)Olefin with polar substituent For example CH H.=CH C=CH HC-C C=N C-O o O--CH Acrylonitrile Nitroethene Methyl methacrylate

2. Monomer (1) Olefin with polar substituent H2 C CH C N H2 C CH N O O H2 C C C O CH3 O CH3 Acrylonitrile Nitroethene Methyl methacrylate For example

(2)Conjugated diene CH HC=CH HC=C styrene a-Me-Styrene H2C=CH-CH=CH2 C-CH-C=C butadiene Isoprene

(2) Conjugated diene H2 C CH H2 C C CH3 H2 C CH CH CH2 H2 C CH C CH2 CH3 styrene a-Me-styrene butadiene isoprene

(3)Reactivity of monomer (Substituting constant: o) Group a H2C=C(CN)2>H2=C-COOC2 Hs >H2C-CH CN NO2 (1.256) (1.150) (0.778) Group b: H2 C=CHCN >H2C=C-CH3>H2c=CH-C-CH CN o (0.66) (0.49) 0.502) HC=CH HC=C-CH 3 Group c: COOCH3 COOCH3 (0.385) (0.215) CH H2C-CH H C=C Group d: Hc三cH-cH=cH (-0.01) (-0.161)

(3) Reactivity of monomer (Substituting constant: s) Group A: Group B: H2 C C(CN) 2 H2 C C CN COOC2 H5 H2 C CH NO2 (1.256) > (1.150) (0.778) > H2 C CHCN H2 C C CN CH3 H2 C CH C O CH3 (0.66) > (0.49) (0.502) > Group C: H2 C CH COOCH3 H2 C C CH3 COOCH3 (0.385) > (0.215) Group D: H2 C CH CH CH2 H2 C CH (- 0.01) H2 C C CH3 (- 0.161)

Reactivity Type of polymerization Groupa R only Group B and group c RR Stronger or weaker Group D RR, R Initiator should be stronger

Group A Group B and group C Group D R R R , R R R + , , >> >> Initiator should be stronger Stronger or weaker only Reactivity Type of polymerization

3. Initiator and initiation (1)alkali metal Lithium (Li a. Species Sodium(Na) b. Initiation Potassium(K) c. Solubility electron Na hccH CH-CH Na transfer dimerize Na CH-CH2 -CH2-CH Na radical couple

3. Initiator and initiation (1) alkali metal Lithium (Li) Sodium (Na) Potassium (K) a. Species b. Initiation c. Solubility - Na H2 C CH electron transfer CH2 CH Na+ + . e - Na - Na CH CH2 CH2 CH + dimerize + radical couple

Solubility of alkali metals K: soluble in ethers Li and Na dispersion homogeneous or heterogeneous insoluble in hydrocarbon Reaction on the surface adsorbtion reaction desorption

K: soluble in ethers Li and Na dispersion: insoluble in hydrocarbon Solubility of alkali metals homogeneous or heterogeneous Reaction on the surface adsorbtion reaction desorption

(2)Alkali metal complex a. Species Aromatic radical-anions: b. Initiation Sodium naphthalene c. Solubility Lithium naphthalene preparation a Na complex(greenish blue color) Alkali metal Aromatic compound initiator

(2) Alkali metal complex - Na Na + + [ ] e complex (greenish blue color) . preparation initiator a. Species b. Initiation c. Solubility Aromatic radical-anions: Sodium naphthalene Lithium naphthalene Alkali metal Aromatic compound

Initiation: Na+ Hc=CH electron transfer CH,CH Na+ radical couple Na CH-CH:CH-CH Nat dimerize Solubility: soluble in polar solvents only such as: ether)

- Na H2 C CH + [ ] . Initiation: + - electron transfer . CH2 CH Na + + - Na - Na + CH CH2 CH2 CH + dimerize radical couple soluble in polar solvents only ( such as: ether) Solubility: