三嵌段共聚物PAN-b-PEG-b-PAN的合成及其自组装行为的研究

利用原子转移自由基聚合(ATRP)制得了分子量可控、分子量分布窄的聚丙烯腈-b-聚乙二醇-b-聚丙烯腈P(AN-b-PEG-b-PAN)嵌段共聚物. 通过¹H NMR, FTIR, 凝胶渗透色谱(GPC)对所得产物的结构和分子量进行了表征并通过TG和DTA考察了该嵌段共聚物的热稳定性; 运用透射电子显微镜(TEM)、荧光探针技术和动态光散射(DLS)研究了P(AN)₂₇-b-P(EG)₄₅-b-P(AN)₂₇在溶剂水中胶束的形成、结构、形貌和胶束粒径. 结果表明, 三嵌段共聚物P(AN)₂₇-b-P(EG)₄₅-b-P(AN)₂₇的热稳定性较纯聚乙二醇P(EG)好, 且柔性链PEG的引入对嵌段共聚物的放热峰位置没有显著的影响. 当改变此嵌段共聚物溶液浓度时, 该嵌段共聚物会自组装成不同形状的胶束, DLS测量的胶束粒径大于TEM观察的结果, 其临界胶束浓度(cmc)约为4.46×10^－4 g•L^－1.

Study on Synthesis of PAN-b-PEG-b-PAN Triblock Copolymer and the Self-assembly Behaviors

Atom transfer radical polymerization (ATRP) was used to synthesize the block copolymers of poly(acrylonitrile)-b-poly(ethylene-glycol)-b-poly(acrylonitrile) (PAN-b-PEG-b-PAN). The copolymers were characterized by using ¹H NMR, FTIR spectra and gel permeation chromatography (GPC). The thermostabilities of these copolymers were investigated by TG and DTA. Transmission electron microscope (TEM), fluorescence spectroscopy and dy-namic light scattering (DLS) were used for the investigation of the self-assembly of the copolymers. Com-paring the thermostabilities of PEG, the thermostabilities of P(AN)₂₇-b-P(EG)₄₅-b-P(AN)₂₇ were improved and the exothermic peak position of the copolymers had no obvious changes when PEG blocks existed. The re-sults of the TEM observations showed that polymeric micelles of P(AN)₂₇-b-P(EG)₄₅-b-P(AN)₂₇ copolymers were almost different shaped, when P(AN)₂₇-b-P(EG)₄₅- b-P(AN)₂₇ copolymer concentrations were altered and micelle size obtained from DLS was bigger than that from TEM and the critical micelle concentration (cmc) of the copolymers was 4.46×10^－4 g•L^－1.