偏氟乙烯/三氟氯乙烯交替共聚物在TATB表面吸附的分子动力学模拟

采用COMPASS力场和NVT正则系综的动力学模拟方法, 搭建了聚合度分别为10, 50和100的偏氟乙烯(VDF)/三氟氯乙烯(CTFE)交替共聚物, 对交替共聚物在1,3,5-三氨基-2,4,6-三硝基苯(TATB)的(0,0,1)晶面上的吸附和结构进行了分子动力学(MD)模拟. 结果表明, 在300～320 K温区, 聚合度为100的VDF/CTFE交替共聚物链对TATB晶体有理想的表面活性和吸附能力, 以train型构象平铺于TATB表面. 通过对聚合度为10的交替共聚物的多链体系在TATB表面吸附的MD模拟, 表明了VDF/CTFE交替共聚物具有非凝聚吸附的高表面活性特征. 对搭建的乙酸乙酯溶剂化的聚合度为50的VDF/CTFE交替共聚物在TATB晶体表面吸附的模拟, 实验证明了溶剂小分子能够降低共聚物链的吸附能力, 且链以tail型构象吸附于TATB表面.

Molecular Dynamics Simulation of Adsorption Characterestics of Alternative Copoly(vinylidene Fluoride-chlorotrifluoroethylene) at the 1,3,5-Triamino-2,4,6-trinitrobenzene Crystals Surface

The absorption characteristics and the structure at (0,0,1) plane of the 1,3,5-triamino-2,4,6-trinitrobenzene crystals of alternative copoly(vinylidene fluoride-chlorotrifluoroethylene) with various degree of polymerization has been studied by molecular dynamics (MD) simulations using compass forcefield and NVT ensemble model. The results show that the adsorbed alternative copolymer chain structured with 100 chain elements possessed a train’s conformation onto TATB surface in moderate temperature range, 300～320 K, owing to its efficient surface activity. The MD simulation results of the absorption behavior of multi-chains of copoly(VDF/CTFE) structured with 10 chain element confirmed that the chains have high surface active performance as individuals sorption. Moreover, when the model includes alternative copoly-mer chain structured with 50 chain elements and 50 solvent molecules, the ability of absorption to the TATB surface of copoly(VDF/CTFE) chain was much decreased. In this case, the adsorbed copoly(VDF/CTFE) chain shows tail’s conformation.