Self-assembly of alternating copolymers and the role of hydrophobic interactions: characterisation by molecular modelling

Abstract

This paper describes the characterisation and the properties of amphiphilic alternating copolymers and their self-assembly into nanoarchitectures in aqueous solution. To investigate the role of the nature of the hydrophobic groups on the association, the self-assembly of two different polymers are compared: poly(isobutylene-alt-maleic anhydride) (IMA) and poly(styrene-alt-maleic anhydride). A structural analysis using computational methods is performed to investigate and characterise the behaviour of IMA chains at different pH values. The optimisation of IMA at different pH values is performed using a complete conformational method which applied both semi-empirical and ab initio molecular modelling methods. The present paper describes in detail the conformational analysis of IMA, the association among IMA chains to form the nanostructures and discusses the influence of the nature of the hydrophobic groups on the association. The theoretical prediction is also compared to experiment.

Keywords:

• poly(isobutylene-alt-maleic anhydride)
• amphiphilic alternating copolymer
• nanoarchitecture
• computational chemistry

Acknowledgements

The authors would like to acknowledge the support of NSERC (Natural Sciences and Engineering Research Council of Canada) and Academic Research Program – RMC. The simulations were performed on the high-performance cluster (HPCVL). We are grateful to Prof. G. Botton and Dr C. Andrei at the Canadian Centre for Electron Microscopy, Brockhouse Institute, McMaster University in Hamilton, Ontario for the generous support and for access to the HR-TEM instruments. We acknowledge Queens University, Kingston, ON for the use of their DLS instrument.