生物可降解聚丁二酸/2,2-二甲基丁二酸丁二酯系列共聚物的合成与性能研究

Synthesis and Properties of Biodegradable Poly(butylene succinate-co-butylene 2,2-dimethyl succinate)

采用丁二酸(SA)、1,4-丁二醇(BD)、2,2-二甲基丁二酸(2MSA)合成了一系列聚丁二酸/2,2-二甲基丁二酸丁二酯共聚物(PBS-2M),利用DSC、1H-NMR和X射线分析等测试手段对共聚物组成、热力学性能、结晶性能、等温结晶行为进行了研究。结果表明,2,2-二甲基丁二酸共聚单元的引入显著改变了聚丁二酸丁二酯(PBS)的热学性能,利用Hoffman-Week曲线得到的共聚物平衡熔点随共聚组分含量的增加显著降低,玻璃化转变温度亦有所降低,结晶熔点则符合无规共聚物的Flory方程。此外,利用Avrami方程对均聚物PBS以及共聚物PBS-2M-20分别进行了等温结晶行为研究,结果表明,共聚使结晶速率降低,PBS和PBS-2M-20的Avrami指数分别介于2.8～3.0和2.6～2.8之间,结晶方式为三维生长异相成核,X射线分析证明共聚不影响晶体结构。

A series of polyesters, poly （hutylene succinate-co-butylene 2, 2-dimethyl succinate） （PBS-2M）, were obtained from the polycondensation of succinate and/or 2,2-dimethyl succinate with 1,4-butanediol. The compositions and physical properties of the resulted homo- and co- polyesters were investigated by ^1H-NMR, differential scanning calorimetry, and X-ray diffraction. The results suggested that the introduction of comonomer containing 2,2-dimethyl side-group led to a change in thermal properties and crystallization behavior. The equilibrium melting temperature obtained by the Hoffman-Weeks plot significantly decreased with increasing concentration of comonomers containing two symmetrical methyl side-groups. Furthermore, Avrami method was used to ranalyze the kinetics of isothermal crystallization of PBS and PBS-2M-20. The Avrami exponents estimated using Avrami plots, ranging from 2. 8 to 3. 0 for PBS and 2. 6 to 2. 8 for PBS-2M-20, indicating that the mechanism of crystallization for both homo- and co-polyester was a tri-dimensional growth with heterogeneous nucleation. Meanwhile, X-ray diffraction showed that there was almost no effect of the 2,2-dimethyl succinate unit on the crystal structure.