Preparation of Nanochitin/Polystyrene Composite Particles by Pickering Emulsion Polymerization Using Scaled-Down Chitin Nanofibers

Kakeru Izaki,Ryuta Watanabe,Jun-Ichi Kadokawa,Kazuya Yamamoto

doi:10.3390/coatings11060672

Abstract

In this study, we investigate the Pickering emulsion polymerization of styrene using scaled-down chitin nanofibers (SD-ChNFs) as stabilizers to produce nanochitin/polystyrene composite particles. Prior to emulsion polymerization, an SD-ChNF aqueous dispersion was prepared by disintegrating bundles of the parent ChNFs with an upper hierarchical scale in aqueous acetic acid through ultrasonication. After styrene was added to the resulting dispersions, the mixtures at the desired weight ratios (SD-ChNFs to styrene = 0.1:1–1.4:1) were ultrasonicated to produce Pickering emulsions. Radical polymerization was then conducted in the presence of potassium persulfate as an initiator in the resulting emulsions to fabricate the composite particles. The results show that their average diameters decreased to a minimum of 84 nm as the weight ratios of SD-ChNFs to styrene increased. The IR and 1H-NMR spectra of the composite particle supported the presence of both chitin and polystyrene in the material.

Highlights

Chitin is one of the most abundant polysaccharides and acts as a structural material in biological systems
The self-assembled chitin nanofibers (ChNFs) film was first fabricated by regeneration from the chitin/AMIMBr ion gel using methanol to produce the ChNF dispersion and subsequent filtration [18]
The average diameters were smaller with increasing SD-ChNF/styrene weight ratios and reached 84 nm with an SD-ChNF/styrene weight ratio of 1.4:1. These results strongly indicate that the SD-ChNFs efficiently acted as stabilizers for the present Pickering emulsion polymerization to fabricate composite particles that were smaller than 100 nm

Summary

Introduction

Chitin is one of the most abundant polysaccharides and acts as a structural material in biological systems It has a regular structure consisting of β(1→4)-linked repeating units of N-acetyl D-glucosamine [1,2,3]. We previously developed a facile method for fabricating chitin nanofibers (ChNFs) with widths of approximately 20–60 nm based on a bottom-up approach where self-assembling regeneration from a chitin/ionic liquid (1-allyl3-methylimidazolium bromide (AMIMBr)) ion gel using methanol was achieved [18,19]. This was based on our finding that AMIMBr efficiently dissolves and swells chitin [20]. Filtration of the resulting ChNF/methanol dispersion resulted in a film with a highly entangled nanofiber morphology

Methods

Results

Conclusion