Fachrichtung Chemie und Lebensmittelchemie, Technische Universität Dresden, D-01062 Dresden, Germany.
Beilstein J Org Chem. 2010 Aug 20;6:756-65. doi: 10.3762/bjoc.6.89.
Linear soluble multi-responsive block copolymers are able to form so called schizophrenic micelles in aqueous solution. Here, such polymers are prepared via nitroxide-mediated radical polymerization (NMRP). In a first step nitroxide-terminated poly(2-vinylpyridine) (P2VP) was prepared with different molecular weights and narrow molecular weight distributions. The best reaction conditions, optimized by kinetic studies, were bulk polymerization at 110 °C. Using P2VP as a macroinitiator, the synthesis of new soluble linear block copolymers of P2VP and poly(N-isopropylacrylamide) (PNIPAAm) (P2VP-block-PNIPAAm) was possible. The nitroxide terminated polymers were characterized by nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Thermal properties were investigated by the differential scanning calorimetry (DSC). Block copolymers showed pH- and temperature-responsive solubility in aqueous media. By increasing the P2VP content, the phase transition temperature shifted to lower temperatures (e.g. 26 °C for P2VP₁₁₄-block-PNIPAAm₁₈₀). Depending on the resulting block length, temperature and pH value of aqueous solution, the block copolymers form so called schizophrenic micelles. The hydrodynamic radius R(h) of these micelles associated with pH values and temperature was analyzed by dynamic light scattering (DLS). Such kind of block copolymers has potential for many applications, such as controlled drug delivery systems.
线性可溶的多重响应嵌段共聚物能够在水溶液中形成所谓的分裂型胶束。在这里，通过氮氧自由基介导的自由基聚合（NMRP）来制备这些聚合物。在第一步中，用不同的分子量和较窄的分子量分布制备了氮氧自由基封端的聚（2-乙烯基吡啶）（P2VP）。通过动力学研究优化了最佳反应条件，即在 110°C 下进行本体聚合。使用 P2VP 作为大分子引发剂，有可能合成新的可溶性线性嵌段共聚物 P2VP 和聚（N-异丙基丙烯酰胺）（PNIPAAm）（P2VP-block-PNIPAAm）。用核磁共振（NMR）光谱、尺寸排阻色谱（SEC）和基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）对氮氧自由基封端聚合物进行了表征。通过差示扫描量热法（DSC）研究了热性能。嵌段共聚物在水介质中表现出 pH 和温度响应的溶解度。通过增加 P2VP 的含量，相转变温度向低温移动（例如，P2VP₁₁₄-block-PNIPAAm₁₈₀ 的相转变温度为 26°C）。根据所得嵌段长度、水溶液的温度和 pH 值，嵌段共聚物形成所谓的分裂型胶束。通过动态光散射（DLS）分析了这些与 pH 值和温度相关的胶束的水动力半径 R(h)。这种嵌段共聚物在许多应用中具有潜力，例如控制药物释放系统。
