Poly(glycerol monomethacrylate)鈥揚oly(benzyl methacrylate) Diblock Copolymer Nanoparticles via RAFT Emulsion Polymerization: Synthesis, Characterization, and Interfacial Activity

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• 作者：Victoria J. Cunningham ; Abdullah M. Alswieleh ; Kate L. Thompson ; Mark Williams ; Graham J. Leggett ; Steven P. Armes ; Osama M. Musa
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：August 26, 2014
• 年：2014
• 卷：47
• 期：16
• 页码：5613-5623
• 全文大小：659K
• ISSN：1520-5835

文摘

A poly(glycerol monomethacrylate) (PGMA) macromolecular chain transfer agent has been utilized to polymerize benzyl methacrylate (BzMA) via reversible addition鈥揻ragmentation chain transfer (RAFT)-mediated aqueous emulsion polymerization. This formulation leads to the efficient formation of spherical diblock copolymer nanoparticles at up to 50% solids. The degree of polymerization (DP) of the core-forming PBzMA block has been systematically varied to control the mean particle diameter from 20 to 193 nm. Conversions of more than 99% were achieved for PGMA₅₁鈥揚BzMA₂₅₀ within 6 h at 70 掳C using macro-CTA/initiator molar ratios ranging from 3.0 to 10.0. DMF GPC analyses confirmed that relatively low polydispersities (M_w/M_n < 1.30) and high blocking efficiencies could be achieved. These spherical nanoparticles are stable to both freeze鈥搕haw cycles and the presence of added salt (up to 0.25 M MgSO₄). Three sets of PGMA₅₁鈥揚BzMA_x spherical nanoparticles have been used to prepare stable Pickering emulsions at various copolymer concentrations in four model oils: sunflower oil, n-dodecane, n-hexane, and isopropyl myristate. A reduction in mean droplet diameter was observed via laser diffraction on increasing the nanoparticle concentration. Finally, the cis diol functionality on the PGMA stabilizer chains has been exploited to demonstrate the selective adsorption of PGMA₅₁鈥揚BzMA₁₀₀ nanoparticles onto a micropatterned phenylboronic acid-functionalized planar surface. Formation of a cyclic boronate ester at pH 10 causes strong selective binding of the nanoparticles via the cis-diol groups in the PGMA stabilizer chains, as judged by AFM studies. Control experiments confirmed that minimal selective nanoparticle binding occurred at pH 4, or if the PGMA₅₁ stabilizer block was replaced with a poly(ethylene glycol) PEG₁₁₃ stabilizer block.