Cellulose is a ubiquitous natural fiber used in various industrial materials and applications. We prepared micron-sized cellulose particles by the solvent releasing method (SRM) in which cellulose-[Bmim]Cl-N,N-dimethylformamide (DMF) droplets are dispersed in hexadecane (HD) containing dissolved surfactant. The dispersion is then poured into a large amount of 1-butanol. Since 1-butanol is miscible with HD, [Bmim]Cl, and DMF but not with cellulose, the cellulose particles precipitate out. FTIR and (1)H NMR analyses confirmed that this technique precipitated cellulose and completely removed [Bmim]Cl and DMF from the cellulose-[Bmim]Cl-DMF droplets. Interestingly, the obtained cellulose particles were almost the same size as the original droplets (cellulose, 7 wt%), indicating a microporous structure of the cellulose particles with a large medium content. Although the microporous structure collapsed as the medium evaporated, it was maintained by a freeze-drying technique.

In this study, reversible addition–fragmentation chain transfer (RAFT) miniemulsion polymerization using a novel type of amphiphilic RAFT agent was investigated. The novel amphiphilic RAFT agent has a specific chemical structure in which a hydrophilic poly(ethylene glycol) chain is directly bonded to the “Z-group” position, and not the leaving group (R group), of the thiocarbonylthio group (RAFT group). As a result, the RAFT groups are localized at the interface of the water/monomer droplets (polymer particles) throughout the polymerization, unlike with a conventional amphiphilic RAFT agent. Polystyrene (PS) particles with a broad molecular weight distribution and 69% degree of livingness were successfully prepared using the novel RAFT agent in a manner similar to that for a conventional RAFT system. Notably, after the completion of polymerization, the RAFT groups could be easily removed from the dispersed PS particles via treatment with an excess of potassium persulfate, because the RAFT groups only exist near the particle surfaces.