Chen Sheng-Qi, Li Jia-Min, Pan Ting-Ting, Li Peng-Yun, He Wei-Dong
CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, China.
Polymers (Basel). 2016 Feb 1;8(2):38. doi: 10.3390/polym8020038.
Dual thermo- and pH-responsive comb-type grafted hydrogels of poly(-dimethylaminoethyl methacrylate) (PDMAEMA) and poly(-isopropylacrylamide) (PNIPAM) with reversed network-graft architectures were synthesized by the combination of atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) polymerization and click chemistry. Two kinds of macro-cross-linkers with two azido groups at one chain-end and different chain length [PNIPAM⁻(N₃)₂ and PDMAEMA⁻(N₃)₂] were prepared with ,-di(β-azidoethyl) 2-halocarboxylamide as the ATRP initiator. Through RAFT copolymerization of DMAEMA or NIPAM with propargyl acrylate (ProA) using dibenzyltrithiocarbonate as a chain transfer agent, two network precursors with different content of alkynyl side-groups [P(DMAEMA--ProA) and P(NIPAM--ProA)] were obtained. The subsequent azido-alkynyl click reaction of macro-cross-linkers and network precursors led to the formation of the network-graft hydrogels. These dual stimulus-sensitive hydrogels exhibited rapid response, high swelling ratio and reproducible swelling/de-swelling cycles under different temperatures and pH values. The influences of cross-linkage density and network-graft architecture on the properties of the hydrogels were investigated. The release of ceftriaxone sodium from these hydrogels showed both thermal- and pH-dependence, suggesting the feasibility of these hydrogels as thermo- and pH-dependent drug release devices.
通过原子转移自由基聚合（ATRP）、可逆加成-断裂链转移（RAFT）聚合和点击化学相结合的方法，合成了具有相反网络接枝结构的聚甲基丙烯酸二甲氨基乙酯（PDMAEMA）和聚N-异丙基丙烯酰胺（PNIPAM）的双温敏和pH响应梳型接枝水凝胶。以α,α'-二（β-叠氮乙基）2-卤代羧酰胺为ATRP引发剂，制备了两种在链端带有两个叠氮基且链长不同的大分子交联剂[PNIPAM-(N₃)₂和PDMAEMA-(N₃)₂]。以二苄基三硫代碳酸酯为链转移剂，通过DMAEMA或NIPAM与丙烯酸炔丙酯（ProA）的RAFT共聚，得到了两种炔基侧基含量不同的网络前驱体[P(DMAEMA-co-ProA)和P(NIPAM-co-ProA)]。大分子交联剂与网络前驱体随后的叠氮-炔基点击反应导致了网络接枝水凝胶的形成。这些双刺激敏感水凝胶在不同温度和pH值下表现出快速响应、高溶胀率和可重复的溶胀/去溶胀循环。研究了交联密度和网络接枝结构对水凝胶性能的影响。头孢曲松钠从这些水凝胶中的释放表现出温度和pH依赖性，表明这些水凝胶作为温度和pH依赖性药物释放装置的可行性。
