Phase Behavior of Polymeric Hairy Nanoparticles in Polymer Melts

摘要

Recently core/shell polymeric nanoparticles have attracted enormous attention in rubber applications [1-20]. This interest is largely based on the fact that nanoparticles having hairy shell and solid core structures might offer superior physical properties in rubber applications [6]. The underlying picture is that the hair molecules may act like flexible bridges that link the hard reinforcing core at one end and entangle the soft host polymer matrix at another end. After vulcanization,all of the shell molecules may be covalently bonded to the rubber network,and thus provide significantly improved reinforcement. In addition,the hairy nanoparticles can be easily modified and tailored through appropriated design of the particle structures for particular applications [5-10],including the core hardness,the shell thickness,the core/shell interface,the hair molecule density,surface functional groups and etc. Beside the importance for applications,the study of the microscopic behavior of the hairy nanoparticles in a polymer melt is of fundamental interest. Theoretically it has been recognized for some time that the interactions between the polymer flat brushes in the presence of free polymers of the same microstructures is primarily determined by entropy-driven forces and the interaction strength can be adjusted by varying the size and the concentration of the free polymers or the grafted brush molecules. However,the effects of interactions between the convex curved brushes are less understood than those between flat brushes. Hence,an investigation of the effects of convex surfaces becomes important for system containing nanoparticles that are slightly larger than the dimension of the grafted chains.