All acrylic block copolymers based on poly (methyl methacrylate) and poly (butyl acrylate). A link between the physico-chemical properties and the mechanical behaviour on impact tests
Résumé
Adding an elastomeric phase in a glassy matrix is extensively used to enhance impact resistance for common commercial polymers (high impact polystyrene or polymethylmethacrylate for example). The domain size of this elastomeric phase can vary in a large range from 100 microns upwards according to the expected optical properties. In contrast to the standard route, block copolymers can present morphology at the nanoscale which can be determined from their phase diagram. All acrylic block copolymers comprising rigid and rubbery blocks tethered together were prepared by a recently developed Controlled Radical Polymerization process, mediated by SG1 nitroxide. In this work, we studied four block copolymers (two diblock and two triblock copolymers) of roughly the same weight average Molecular Weight and the same composition of PolyMethylmethacrylate and PolyButylacrylate. The behaviour during impact tests is linked to the processing conditions: injection moulding or solvent-casting. We show that the nanoscale order, characterised here by the lamellar period size and obtained by solvent-casting, strongly influences the impact resistance. © 2008 Elsevier Ltd. All rights reserved.