Spontaneous Nanoparticle Dispersal in Polybutadiene by Brush-Forming End-Functional Polymers

A masterbatch additive for the enhanced dispersal of bare silica nanoparticles in polybutadiene is demonstrated using tetrahydroxyl end-functional polybutadienes (“4OH-PBd”). Neutron reflectometry and small-angle neutron scattering (SANS) confirm the efficient end-adsorption of 4OH-PBd at a planar silica interface and silica particle interfaces of increasing complexity. SANS on well-defined model Stober silica nanospheres in polybutadiene revealed spontaneous 4OH-PBd adsorption, forming a “shell” around the silica nanospheres. Analysis using a core–shell fractal model showed that the extent of adsorption was consistent with the interfacial excess determined by NR. The utility of 4OH-PBd additives to disperse silica nanoparticles was explored rigorously for a range of compositions and additives. Successful silica nanoparticles dispersal was evident from a reduction in the correlation length of the largest structures in the mixture and increase in fractal dimension, ascribed to a breakdown of percolating na...