Abstract
In this work, we present a novel synthetic route to diblock copolymers based on styrene and 3-vinylpyridine monomers. Surfactant-free water-based reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization of styrene in the presence of the macroRAFT agent poly(3-vinylpyridine) (P3VP) is used to synthesize diblock copolymers with molecular weights of around 60 kDa. The proposed mechanism for the poly(3-vinylpyridine)-block-poly(styrene) (P3VP-b-PS) synthesis is the polymerization-induced self-assembly (PISA) which involves the in situ formation of well-defined micellar nanoscale objects consisting of a PS core and a stabilizing P3VP macroRAFT agent corona. The presented approach shows a well-controlled RAFT polymerization, allowing for the synthesis of diblock copolymers with high monomer conversion. The obtained diblock copolymers display microphase-separated structures according to their composition.
Highlights
Free radical polymerization provides a feasible and robust route towards the polymerization of a variety of vinyl monomers
We describe the reversible addition–fragmentation chain transfer polymerization (RAFT) synthesis of diblock copolymers formed by poly(3-vinylpyridine) and polystyrene using the polymerization-induced self-assembly (PISA) approach
In order to conduct the surfactant-free emulsion polymerization, the solubility of the unstabilized macroRAFT agent in water-based solution is essential at room temperature and reaction temperature
Summary
Free radical polymerization provides a feasible and robust route towards the polymerization of a variety of vinyl monomers. The lack of control over molecular weight, chain architecture and topology restrains the utility of polymers prepared by radical polymerization in many applications [1]. The necessity to govern the molecular weight, the dispersity and the molecular architecture has directed researchers towards controlled or “living” radical polymerization (CRP) which has developed into a versatile and widely used tool to synthesize well-defined polymer structures [2]. In addition to a variety of other controlled radical polymerization techniques, reversible addition–fragmentation chain transfer polymerization (RAFT) is of particular importance due to its functional group tolerance and the particular applicability for the synthesis of well-defined polymers [1,3,4,5,6]. Many research groups work on RAFT polymerization of various monomers and, especially for the case of vinyl pyridine monomers, a variety of research works can be found in Materials 2019, 12, 3145; doi:10.3390/ma12193145 www.mdpi.com/journal/materials
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