Non-Isothermal Degradation Kinetics of Hybrid Copolymers Containing Thermosensitive and Polypeptide Blocks

• 作者: Emilya D. Ivanova Ivaylo V. Dimitrov Sevdalina Christova Turmanova Velyana G. Georgieva
• 来源期刊: 高分子化学期刊(英文)
• 学科: 化学
• 关键词: Self-Associating HYBRID COPOLYMERS N-CARBOXYANHYDRIDE of Z-L-Lysine (Z-L-Lys-NCA) Thermal Stability Properties NON-ISOTHERMAL Degradation Kinetics
• 年，卷（期）: 2012,（3）
• 页码范围: 91-98
• 页数: 8页
• 分类号: O6

摘要

Novel, self-associating hybrid copolymers were synthesized via controlled ring-opening polymerization of N-carboxyanhydride of Z-L-lysine (Z-L-Lys-NCA), initiated by amino-functional macroinitiators. A poly(N-isopropylacry-lamide) (PNIPAm)-based macroinitiator containing 10 mol% of polyoxyethylene grafts and a terminal primary amine group in the form of ammonium hydrochloride (PNIPAm-g-PEО) was synthesized and used to initiate the ammonium- mediated ring-opening polymerization of NCA described by Dimitrov and Schlaad [1]. Thus, hybrid copolymers ((PNIPAm-g-PEO)-b-PLys) with controlled molar-mass characteristics and functionality were obtained. The potential applications of PNIPAm-based copolymers in the systems for controlled drug release, immobilization of enzymes and protein purification have aroused great interest in the studies of their properties and behaviour. The thermal stability and thermodynamic properties of the copolymers obtained were studied. The differential thermal analysis of polyfunctional hybrid copolymers (PNIPAm-g-PEO)-b-PLys) showed that thermooxidative destruction occurs in two stages: primary, of the unstable fragments (grafted chains of PEO);and secondary, of the main polymer chains of poly(N-isopropylacry-lamide) and poly(L-lysine). The kinetics of thermal degradation was evaluated and the values of the activation energy of the degradation process, changes of Gibbs free energy, enthalpy and entropy for the formation of the activated complex were also calculated.