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

James M Hart,Arwel V Hughes,Nigel Clarke,Budhika Mendis,Isabelle Grillo,Victoria Garcia-Sakai,Sarah E Rogers,Lian R Hutchings,Richard L Thompson,Solomon M Kimani

doi:10.1021/acs.macromol.5b02318

Abstract

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...

Highlights

Composite and nanocomposite materials offer significant advantages over unfilled polymers, notably in mechanical, thermal, and optical properties, with greater strength, resistance to heat, and photodegradation being among these desirable properties
Energy efficiency is substantially compromised by strain softening (Payne) and hysteresis (Mullins) effects, which are prevalent in filled rubbers.[1−4] Remarkably for this mature technology, there is still debate over the exact cause of reinforcement and associated phenomena such as energy dissipation, it is apparent that the distribution of filler particles and their interactions with each other and the surrounding polymer are of central importance
Specular neutron reflectivity data were fitted to scattering length density (SLD) profile using Motofit Software running on Igor.[22]

Summary

Introduction

Composite and nanocomposite materials offer significant advantages over unfilled polymers, notably in mechanical, thermal, and optical properties, with greater strength, resistance to heat, and photodegradation being among these desirable properties. These benefits are perhaps best exemplified by the very successful use of filler particles in car tires. For other applications, controlling nanoparticle dispersion in polymers for magnetic inks and data storage is a current challenge,[5] and polymer reinforcement, e.g. with graphenebased fillers, requires control over the polymer−particle interface.[6] Given these drivers, there is of considerable interest in controlling the dispersion and organization of filler particles in rubbery polymers and the relationship between structure and performance

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