基于分子动力学模拟的类固态等温微热压印过程分析  

Analysis of isothermal micro-hot embossing in the solid-like state based on molecular dynamics simulations

作　　者：李瑞[1] 吴大鸣[1,2] 王琦[1] 刘颖[1] 郑秀婷[1] 孙靖尧[1] 

机构地区：[1]北京化工大学机电工程学院,北京100029 [2]北京化工大学高分子材料加工装备教育部工程研究中心,北京100029

出　　处：《北京化工大学学报（自然科学版）》2018年第1期36-42,共7页Journal of Beijing University of Chemical Technology(Natural Science Edition)

基　　金：国家自然科学基金(51673020);中央高校基本科研业务费(ZY1616)

摘　　要：基于Materials Studio软件,构建类固态等温微热压印体系模具镍与无定形聚合物聚甲基丙烯酸甲酯(PMMA)的片层界面模型。根据凝聚态材料的适用性,选取COMPASS分子力场用于热压体系的计算。首先,对微热压印微结构的填充阶段进行模拟和分析,用体系能量随时间由波动逐步趋于稳定和分子密度不断升高并趋于稳定的变化规律来解释热压填充体系的建立过程。其次,对保压松弛阶段进行模拟和分析,并从以下3个微观角度解释了类固态微热压印过程中聚合物的应力松弛现象:(1)PMMA分子链均方回转半径逐渐减小至稳定;(2)速度相关系数迅速衰减并在0附近波动,说明聚合物的内应力衰减并最终趋于稳定;(3)不同温度对均方回转半径与速度相关系数的影响规律。A lamellar interface model of the solid-like isothermal micro-shot embossing of mold nickel and amor- phous polymer PMMA has been constructed using the Materials Studio software package. Based on its applicability to the condensed material, the COMPASS molecular force field was chosen for the calculations on the hot embossing system. The establishment of the mold-filling system was first explained in terms of the variation of the system energy, which fluctuated gradually and then became stable. The molecular density increased and tended to become stable over time during the mold-filling of the micro-structure, as shown by both simulation and analysis. In addition, the stress relaxation phenomenon of the polymer in the process of isothermal hot embossing in the solid-like state was explained in terms of the following three microcosmic factors by simulation and analysis of the stress relaxation during the dwell stage ： （ 1 ） The mean-square radius of gyration of the PMMA molecular chain gradually decreased and became stable; （2） The velocity correlation coefficient rapidly attenuated and fluctuated near zero, which indi- cated that the internal stress of the polymer decayed to become stable ; （3） The influence of different temperatures on the meanquare radius of gyration and the velocity correlation coefficient.

关 键 词：分子动力学 类固态等温微热压印 保压松弛 微结构填充 

分 类 号：TQ325.1[化学工程—合成树脂塑料工业]