Higashi Nobuyuki, Matsubara Sho, Nishimura Shin-Nosuke, Koga Tomoyuki
Department of Molecular Chemistry and Biochemistry, Faculty of Science and Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan.
Materials (Basel). 2018 Mar 15;11(3):424. doi: 10.3390/ma11030424.
Novel thermo-responsive ABA-type triblock copolymers (poly(NAAMe--NAGMe--NAAMe), = 18-72) composed of naturally occurring amino acid-based vinyl polymer blocks such as poly(-acryloyl-l-alanine methyl ester (poly(NAAMe)) as the A segment and poly(-acryloyl-glycine methylester)(poly(NAGMe)) as the B segment have been synthesized by the atom transfer radical polymerization (ATRP). Their thermal behaviors were analyzed in dilute aqueous solutions by turbidimetry. The turbidity curves provided two-step LCST transitions, and a flower-like micelle formation was confirmed at the temperature region between the first and second LCST transitions by dynamic light scattering, AFM and TEM. At higher copolymer concentrations, hydrogels were obtained at temperatures above the first LCST due to network formation induced with the flower-like micelles as cross-linker. The hydrogels were found to be switched to a sol state when cooled below the first LCST. These hydrogels also exhibited self-healable and injectable capabilities, which were evaluated by rheological measurements.
通过原子转移自由基聚合（ATRP）合成了新型热响应性ABA型三嵌段共聚物（聚（NAAMe-NAGMe-NAAMe），n = 18-72），其由天然存在的基于氨基酸的乙烯基聚合物嵌段组成，例如作为A段的聚（-丙烯酰基-L-丙氨酸甲酯）（聚（NAAMe））和作为B段的聚（-丙烯酰基-甘氨酸甲酯）（聚（NAGMe））。通过比浊法在稀水溶液中分析了它们的热行为。浊度曲线提供了两步最低临界溶液温度（LCST）转变，并且通过动态光散射、原子力显微镜（AFM）和透射电子显微镜（TEM）在第一次和第二次LCST转变之间的温度区域证实了花状胶束的形成。在较高的共聚物浓度下，由于以花状胶束作为交联剂诱导形成网络，在高于第一次LCST的温度下获得了水凝胶。发现当冷却至低于第一次LCST时，这些水凝胶转变为溶胶状态。通过流变学测量对这些水凝胶的自愈和可注射能力进行了评估。
