高分子线团中特定基团分布的分析方法

A Characterization of the Location of Special Groups in Polymer Coil

目的 :描述高分子线团中特定基团的分布情况。方法 :以线团质心和第i个特定基团的质心的连线为轴线 ,以适合的半径R做一虚拟圆柱 ,从线团质心开始 ,沿轴线方向 ,以合适的步长将圆柱分成若干个小圆柱 ,统计每一小圆柱中的原子个数 ,根据小圆柱内的原子个数确定线团在该方向的边缘 ,从而确定基团的相对位置。研究所有的特定基团后 ,就可求出起分布。结果 :将该方法应用到乙烯 -苯乙烯共聚物中苯环侧基的分析中 ,结果表明苯环主要位于线团的外部 ,苯乙烯含量高时 ,线团内部的苯环含量增加。结论 :该方法可以准确描述高分子线团中特定基团的分布。该方法也可用于表征支化点的位置。

A method was proposed in order to characterize the location of special groups in polymer coil. In this method, a virtual cylinder is drawn with proper radius along the axis, which connects the center of mass of the coil and that of the phenyl group. The atom number (ns) is counted every other step in the cylinder (along the axis) from the center of mass of the coil. The border of the coil is defined based on ns, and the relative location can be obtained. The location of special groups can be obtained after researching all special groups. This method was applied to characterize the location of phenyl groups in a system of ethylene-styrene copolymers. The results show that phenyl groups mainly locate on the shell of the coil, and content of phenyl groups located inside increases with that of styrene. The method can describe the location of special groups in polymer coil, and can also be used to characterize the location of branch point.