Surfactant-free nanoencapsulation using reactive oligomers obtained by reversible addition fragmentation chain transfer polymerization of styrene and maleic anhydride

Abstract

Reactive oligomers of styrene–maleic anhydride having controlled architecture were prepared using reversible addition fragmentation chain transfer (RAFT) polymerization. The co-oligomers were characterized by FTIR, Raman, NMR and GPC. The arrangement of co-monomers (i.e. the architecture) in the co-oligomeric RAFT agents could be controlled by changing the molar feed ratio of styrene to maleic anhydride in the range of 1–5.25 under controlled polymerization conditions. Non-alternating (homopolymer) blocks of styrene could be suppressed even at high mole ratios > 1 and the resultant co-oligomeric RAFT agents consisting of mainly alternating (SMS) and semi-alternating (SSM) sequences of styrene and maleic anhydride were obtained. These macro RAFT agents behaved as efficient reactive surfactants and their self-aggregation behavior was greatly influenced by their architecture. These could be successfully used for surfactant-free nanoencapsulation of active hydrophobic materials, such as n-octadecane, indicating their suitability for various applications.