聚乙烯单晶纳米力学性质的单分子力谱研究

摘要

Semi-crystalline polymers have been widely used as plastic, fiber and elastomers due to their excellent mechanical properties. As is well known, semi-crystalline polymer materials are composed of crystal and amorphous phases, and crystal phase plays very important roles in their mechanical properties. However, it is very difficult to discern the contribution of crystalline phase to the mechanical properties using traditional methods. Here, we study the mechanical properties of single polyethylene ( PE ) molecule within its single crystal using combined techniques of atomic force microscopy( AFM) imaging and AFM-based single-molecule force spectroscopy ( SMFS ) . The results show that the apparent mechanical stability of single PE chain significantly increased with the increase of the thickness of PE single crystal. The stiffer loading device greatly enhanced the unfolding force of the single PE chain and promoted the formation of intermediates during unfolding process. These results deepen understanding on the origin of mechanical properties of PE single crystal, and may be useful for tuning the mechanical response of corresponding polymer materials.%基于原子力显微镜(AFM)的单分子力谱技术(SMFS),在单分子水平上研究聚乙烯单晶中单分子链在外力诱导下的熔融过程.研究表明,随着聚乙烯单晶厚度的增加,熔融解链过程需要破坏的作用位点随之增加,解链力值显著提高;刚性力加载装置会降低作用位点解离速率,进而升高解链力值,促进力学稳定性相对较差的中间态形成.