Abstract
A hydrophobic CCS polymer of poly(benzyl methacrylate) (PBzMA) was prepared in toluene by reversible addition-fragmentation chain transfer (RAFT)-mediated dispersion polymerization. The CCS polymer, with poly(benzyl methacrylate) as the arm and crosslinked N, N′-bis(acryloyl)cystamine (BAC) as the core, was confirmed by characterization with gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy. Three kinds of oils (toluene, anisole and styrene) were chosen to study the emulsification properties of PBzMA CCS polymer. The oils can be emulsified by CCS polymer to form water-in-oil (w/o) emulsions. Moreover, w/o high internal phase emulsions (HIPEs) can be obtained with the increase of toluene and styrene volume fractions from 75% to 80%. Porous polystyrene monolith and microparticles were prepared from the emulsion templates and characterized by the scanning electronic microscopy (SEM). With the internal phase volume fraction increased, open-pore porous monolith was obtained.
Highlights
We reported that core cross-linked star (CCS) polymers, which advocate their role as an intermediate between linear polymers and polymeric nanoparticles, can act as effective interfacial stabilizers for emulsions[18]
L-poly(benzyl methacrylate) (PBzMA) arm was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization controlled by S-(2-cyanoprop-2-yl)-S-dodecyltrithiocarbonate as the RAFT agent and AIBN as initiator at 70 °C in anisole
The L-PBzMA arm was used as the macro-CTA to prepare PBzMA CCS polymer (S-PBzMA) using N, N′-Bis(acryloyl)cystamine (BAC) as the cross-linker
Summary
We reported that core cross-linked star (CCS) polymers, which advocate their role as an intermediate between linear polymers and polymeric nanoparticles, can act as effective interfacial stabilizers for emulsions[18]. Poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA)[19, 20], poly(MEA-co-PEGA) (MEA is 2-methoxyethyl acrylate, PEGA is poly(ethylene glycol) acrylate)[21] and styrenic imidazole-based CCS polymers[22] are all excellent emulsifiers to stabilize oil-in-water (o/w) emulsions and HIPEs. So far, w/o emulsions and HIPEs has not been formed because most of the CCS polymers are hydrophilic. Even for less hydrophilic styrenic imidazole-based CCS polymer (S-PVBnIm), o/w HIPEs were still formed rather than w/o emulsions. For HIPEs, one important application is used as template to prepare porous materials[23, 24]. For o/w HIPEs, hydrophilic materials were achieved by polymerizing the hydrophilic monomers in the continuous phase and removing the dispersed oil phase. In order to broaden the application of CCS polymers in w/o HIPEs, hydrophobic poly(benzyl methacrylate) (PBzMA) CCS polymer was prepared. Emulsion stability was verified by synthesis of porous polystyrene monolith and microparticles
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