Matrix free polymer nanocomposites from amphiphilic hairy nanoparticles: Solvent selectivity and mechanical properties

Abstract

Matrix free polymer nanocomposite of spherical nanoparticles with shells made of amphiphilic homopolymer was studied in molecular dynamics experiments. The amphiphilic homopolymer was presented as sequence of identical monomer units, each containing two beads having different affinity to solvent. The self-assembly in solution of such hairy nanoparticles was studied depending on solvent quality and selectivity for different polymer concentrations. Two of the most characteristic morphologies were identified and described. The first one is a structure resembling a mixture of sea hedgehogs. There is a nanoparticle in the core of a hedgehog, and the spines consist of several grafted chains. Hedgehogs float freely, do not aggregate with other nanoparticles, their solutions have a low moduli of elasticity and viscosity up to a fairly high polymer concentration. The second morphology is thin membrane lamellae assembled from amphiphilic homopolymers. In this case, the nanoparticles are joined into a single network-like aggregate at very low polymer concentrations. Such networks possess a unique porous structure and demonstrate high elasticity and viscosity moduli. These findings could be useful for molecular design of smart materials, that are able to reversibly assemble, disintegrate on request and repair damage by self-healing mechanism. • Nanoparticles, coated with amphiphilic homopolymers, are studied. • Such nanoparticles can self-assemble either into gels or into “hedgehogs” mixture. • Gels have membrane-like, porous structure, and demonstrate elastic and viscous response. • Core-shell filaments preserve aggregation and favor uniform distribution of “hedgehogs”. • Structure type is determined by solvent quality and selectivity.