Preparation of core–shell nanoparticles via emulsion polymerization induced self-assembly using a maleamic acid-α-methyl styrene copolymer as a macro-initisurf

Abstract

Polymerization induced self-assembly (PISA) is a promising route to prepare nanoparticles with various morphologies at high solid content and has attracted intensive attention in the past few decades. In this study, an amphiphilic maleamic acid-α-methyl styrene copolymer (MAA-alt-AMS, macro-initisurf) was synthesized, which acted as a macroinitiator and emulsifier for the emulsion polymerization induced self-assembly of acrylate monomers to prepare core–shell nanoparticles comprised of MAA-alt-AMS as the shell and poly(methyl methacrylate-ran-butyl acrylate) as the core. Using DPPH as a radical scavenger, the thermal-induced decomposition of MAA-alt-AMS chains was investigated. The results showed that the polymer chains of MAA-alt-AMS can be clefted to generate macromolecular radicals to initiate the polymerization of monomers at a temperature above 70 °C. The chain scission of MAA-alt-AMS can be regarded as the first-order reaction and the activation energy of decomposition is determined to be 62.81 kJ mol⁻¹. The emulsion PISA of acrylate monomers initiated by the macro-initisurf shows a high conversion, which can reach almost 100% with a mass ratio of the macro-initisurf to monomers of 2 : 5 and the obtained spherical nanoparticles possess a shell–core structure and narrow size distribution (PDI < 0.05). The size of nanoparticles can be tuned from 80 to 200 nm by changing the macro-initisurf content, monomer ratio and reaction temperature, while the thickness of the shell remained around 20–30 nm regardless of reaction conditions. The MAA-alt-AMS triggered emulsion PISA has the advantages of a short reaction time (can be finished within 2 h) and a high solid content (up to 50%), and has great potential in large scale industrial application.