双亲性光敏感遥爪聚合物C-PNIPAAm的合成与性能

以7-羟基-4-甲基香豆素为原料,依次与环氧氯丙烷、二硫化钠反应得一含香豆素基元的二硫化物(C-S-S-C),并以其与三丁基膦复合体系为链转移剂,偶氮二异丁腈(AIBN)为引发剂,N-异丙基丙烯酰胺(NIPAAm)为单体制备了末端为香豆素光响应基元的双亲性遥爪聚合物(C-PNIPAAm).用傅里叶变换红外(FT-IR)光谱、凝胶渗透色谱(GPC)、氢核磁共振(1H-NMR)等对该聚合物进行了结构表征.研究显示该双亲性遥爪聚合物可在水中直接形成胶束,并以荧光素为疏水性客体考察了聚合物胶束的光控释放行为.在波长大于310 nm的紫外光照射下,聚合物链末端的香豆素单元可进行光二聚,胶束结构随之改变,因而所负载的荧光素可得到逐步有效释放.动态激光光散射(DLS)检测显示,光二聚反应使聚合物胶束平均粒径从56.6 nm增大至101.0 nm.

Synthesis and Properties of Amphiphilic Photosensitive Telechelic Polymer C-PNIPAAm

Coumarin-containing disulfide (C-S-S-C) was designed and synthesized, which could be used as chain transfer agent with tributylphosphine and water. With N-isopropyl acrylamide (NIPAAm) as monomer and azodiiso- butyronitrile (AIBN) as initiator, an amphiphilic photosensitive telechelic polymer (C-PNIPAAm) was synthesized. The polymer was characterized by Fourier transform infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC) and proton nuclear magnetic resonance spectroscopy (¹H-NMR). We found that the polymer can form micelles in water itself with fluorescein as a hydrophobic agent. When irradiated by UV light (λ>310 nm), the coumarin unit at the end of the polymer chain was photodimerized, which changed the micelle structure and hydrophobic fluorescein was effectively released to the water. Dynamic laser scattering (DLS) showed that the average diameter of the micelles increased from56.6 nmto 101.0 nmafter irradiation.