丙烯腈-苯乙烯嵌段共聚物的RAFT聚合与表征

Synthesis and Characterization of Acrylonitrile-Styrene Block Copolymer Prepared by RAFT Technique

以S,S′-二(α,α′-二甲基-α″-乙酸)三硫代碳酸酯(TRIT)为链转移剂,利用可逆加成断裂链转移自由基聚合(RAFT)制备了窄分布的端羧基大分子链转移剂——聚苯乙烯和聚丙烯腈。以大分子链转移剂为RAFT试剂,引发苯乙烯或丙烯腈单体的RAFT聚合,进一步得到聚丙烯腈-聚苯乙烯-聚丙烯腈(PAN-b-PS-b-PAN)和聚苯乙烯-聚丙烯腈-聚苯乙烯(PS-b-PAN-b-PS)三嵌段共聚物。通过1 H-NMR、FT-IR、凝胶渗透色谱(GPC)对所得产物的结构和分子量进行了表征,通过原子力显微镜(AFM)和拉曼光谱(Raman)研究了嵌段共聚物薄膜的微相分离结构与热解行为。结果表明:所得产物中除PAN-b-PS-b-PAN外,分子量分布均小于1.2。嵌段共聚物薄膜经250℃热稳定化与600℃热解处理后,碳化并形成了规整的石墨结构,微区尺寸在75nm左右。

Carboxyl-terminated polyacrylonitrile and polystyrene as macro-RAFT agents were synthesized by reversible addition-fragmentation chain transfer （RAFT） polymerization using S, S＇-bis （a, a＇-dimethyl- a＂-acetic acid）-trithiocarbonate as the chain transfer agent. Poly （ acrylonitrile）-b-poly （ styrene）-b-poly （acrylonitrile） （PAN-b-PS-b-PAN） and poly （ styren）-b-poly （ acrylonitrile）-b-poly （ styrene ） （ PS-b-PAN-b- PS） trihloek copolymers were synthesized using acrylonitrile and styrene as monomers and macro-RAFT agent as the chain transfer agents, respectively. The molecular structure and molecular weight of the pro- ducts were characterized using ^1H-NMR, FT-IR spectra and gel permeation chromatography （GPC）. Atomic force microscope（AFM） and Raman spectra were used to study the microphase separation structure and pyrolysis behavior of the block copolymer films. Results showed that the molecular weight distribution （PDI） of the resulting products,except PAN-b-PS-b-PAN,was less than 1.2. After stabilization at 250 ℃ and pyrolysis at 600 ℃, thin films of block copolymer carbonized to uniform graphite structure about 75 nm in size.