可还原降解梳形阳离子聚合物的合成

SYNTHESIS OF REDUCTIVELY DEGRADABLE COMB-LIKE CATIONIC POLYMER

通过缩合聚合和可逆加成-断裂链转移聚合(RAFT)合成了一种新型可还原降解的梳形聚阳离子.首先,以具有化学选择性的三氟甲磺酸钪催化苹果酸、二硫二丙酸、癸二醇的三元缩合聚合得到了含多个侧羟基的聚(苹果酸-co-二硫二丙酸)癸二酯;将羟基酯化修饰为双硫酯后,通过甲基丙烯酸二甲氨基乙酯(DMAEMA)的RAFT聚合制备了梳型聚甲基丙烯酸二甲氨基乙酯(PDMAEMA).采用1H-NMR和GPC等测试方法对该聚合物进行结构表征.该梳形阳离子聚合物在还原性环境中可通过双硫键的断裂降解成为小分子量PDMAEMA低聚物.

A reductively degradable cationic polymer with comb-like architecture was synthesized by a combination of polycondensation and reversible addition and fragmentation chain transfer radical polymerization （RAFT）. First, the direct polycondensation of deeanediol, 3,3＇-dithiodipeopionie acid and malic acid was carried out using scandium triflate as catalyst. Due to the chemoselectivity of scandium triflate for esterification,the secondary hydroxyl groups of malic units were not esterified during the polycondensation process, resulting in functional polyester with numerous disulfide bones and hydroxyl groups. Then the pendant hydroxyl groups were modified into dithioester form in the presence of N,N＇-dicyelohexylcarbodiimide （DCC） and 4-dimethylaminopyridine （DMAP） ,to give a macromolecular chain transfer agent,which could be used as multifunctional backbone to prepare comb-like polymer by ＂ grafting from＂ method. Finally, the poly （2- （dimethylamino） ethyl methacrylate） （PDMAEMA） side chains were attached to the backbone via RAFT polymerization of 2-（dimethylamino） ethyl methacrylate. The comb-like architecture of the copolymer was characterized by ^1H-NMR and GPC. The reducible degradation of the comb-like polycation was studied in the presence of tributylphosphane as reducing agent, which demonstrated the cleavage of disulfide bonds in the backbone under reductive environment, resulting in low molecular weight PDMAEMA oligomers. This comb-like cationic polymer may have potential applications in gene delivery,which is being investigated in our research group.