结合分子模拟探讨液体复合材料中改性PBS与纤维素衍生物之间的相互作用
Interactions between modified PBS and cellulose derivatives in liquid composites with molecular simulation

采用聚乙二醇(PEG)改性的聚丁二酸丁二醇酯(PEG/PBS)分别与改性纤维素羧甲基纤维素(CMC)和羟乙基纤维素(HEC)共混制备了在水相均匀分散的聚酯/纤维素新型液体复合材料, 并结合分子模拟技术对液体复合材料间的相互作用机制进行了研究.结果表明: 1H-NMR证明了PEG/PBS共聚物具有预期的化学结构; 分子动力学模拟表明PBS呈现螺旋结构, PEG的引入改变了其结构的规整性, 且有效提高了共聚物分子链的极性和柔顺性, 改善了其与纤维素衍生物的相容性.复合材料的能量分布结果表明PEG/PBS中醚、 酯基官能团与纤维素衍生物中的羟基官能团之间存在较强的氢键作用和范德华力.FTIR谱图中官能团(如—OH、 —OCO—、 —COOH、 —C—O—C—等)吸收峰频率的偏移、 SEM照片中表界面形态的变化、 EDS能谱中C和O元素的含量变化等表明PBS及其醚化PEG/PBS与CMC的官能团之间发生了相互作用, 且醚化改性后相互作用增强, 复合材料的透过率由50%提高到70%以上, 热稳定性和柔韧性均提高, 验证了分子模拟的结果. Novel liquid composites of polyester/cellulose evenly dispersed in aqueous phase were prepared by blending polyethylene glycol (PEG) modified poly(butylene succinate) (PEG/PBS) and modified cellulose carboxymethylcellulose (CMC) and hydroxyethyl cellulose (HEC) respectively. The interaction mechanism of liquid composites was investigated by molecular simulation technology. The results show that the desired structure of PEG/PBS copolymer is successfully achieved by 1H-NMR. Molecular dynamics simulation displays that the polarity and flexibility of copolymer chain have been effectively improved by the modification on double helix structure of PBS with PEG. The introduction of PEG changes the structure regularity. As a consequence, the compatibility between it and cellulose derivatives is improved. The analysis on energy distribution of composites indicates that strong hydrogen bonding and Van der Waals interaction exist between ether and ester group of PEG/PBS and hydroxyl groups of cellulose derivatives. These results have been explained by the deviation of absorption peak frequency on functional groups (such as OH, -OCO-, -COOH and -C-O-C-) in FTIR spectra, the change of surface interfacial morphologies in SEM photographs and the content change of C and O elements in EDS spectrum. The results show that the interaction is produced between functional groups of PBS, etherification PEG/PBS and CMC. And the interaction is improved after etherification modification. The transmittance of composites increases from 50% to more than 70%, the thermal stabilities and flexibility are also enhanced which verifies the results of molecular simulation. 国家"863"计划(2011AA100503);酿酒生物技术及应用四川省重点实验室开放基金(NJ2013-07);陕西省自然科学基础研究计划(2015JM2069)