梳状丙烯酸酯类共聚物凝胶电解质的传输性能与自由体积

用三种分子量大小不等的聚乙二醇单甲醚(PEGME)与甲基丙烯酸甲酯-马来酸酐共聚物P(MMA-co-MAh)]反应,制备了三种支链长度不等的梳状共聚物(MMA/MAh-g-PEGME), 并以此为基体, 加入增塑剂碳酸丙烯酯(PC)和高氯酸锂(LiClO₄), 采用溶剂浇铸法制备了三种凝胶聚合物电解质(GPE)膜, 研究了其离子传输性能, 发现该聚合物凝胶电解质的离子传输机理符合VTF (Vogel-Tamman-Fulcher)方程, 即离子传输性能与凝胶体系自由体积的大小有关; 采用正电子湮没寿命谱仪(PALS)研究了GPE 体系的自由体积特性, 获得了各支链长度不同的共聚物凝胶电解质的自由体积分数, 分析各自由体积与离子传输性能之间的关系, 建立了共聚物结构、凝胶聚合物自由体积及其传输性能之间的关系. 发现梳状共聚物支链长度越长, 凝胶电解质的自由体积越大, 离子传输性能越高.

Transmission Performance and Free Volume of Gel Electrolyte Membranes Based on Comblike Methyl Methacrylate Copolymers

Three comb-like methyl methacrylate copolymer matrixes for gel polymer electrolyte(GPE) were synthesized by reacting methyl methacrylate-maleic anhydride copolymer(P(MMA-co-MAh)) with poly(ethylene glycol) monomethylether(PEGME) of different molecular weight(350,600,and 750),re-spectively.Three kinds of GPE membranes made from comb-like copolymers as matrix,shorted for CL350,CL600,CL750,propylene carbonate(PC) as plasticizer and LiClO4 as salt,have been prepared by solution casting technique.By studying the ion transporting properties of the GPE,it is found that the conduction mechanism of the GPE accords with VTF(Vogel-Tamman-Fulcher) equation,which is derived from free volume theory.Positron annihilation lifetime spectroscopy(PALS) was employed to analyze the properties of free volume in GPE systems and the effect of microstructure on conductivity of GPE membranes.It is noted that increasing the side chain length of polymer matrixes will increase the free volume existed in sys-tem.When the content of polymer matrix is 45 wt%,free volume in CL750 based GPE membrane is 21% larger than that in CL350 based GPE membrane.Correspondingly,compared with CL350 system,the ionic conductivity of CL750 system grows by 200%.It is apparent that the ionic conductivity of GPE membranes is affected by the structure of polymer matrix to a great extent.