Interfacial living radical copolymerization of oil‐ and water‐soluble comonomers to form composite polymer capsules

Abstract

The suspension copolymerization of methyl methacrylate with hydroxy‐functional poly(ethylene glycol) monomethacrylate (PEGMA) by atom transfer radical polymerization (ATRP) yielded soluble, controlled‐molecular‐weight amphiphilic copolymers (weight‐average molecular weight/number‐average molecular weight <1.3). Despite extensive partitioning of PEGMA into the water phase, copolymers containing up to 24 mol % PEGMA were formed in the oil phase, from comonomer feeds containing 30 mol % PEGMA. Conversions by suspension polymerization were comparable to those obtained by solution polymerization, at over 70%. Suspension copolymers with high PEGMA contents contained high‐molecular‐weight polymer formed by uncontrolled polymerization, unless poly(vinyl pyrrolidone) was added to displace the growing polymer from the interface. The addition of diethylene glycol dimethacrylate gave capsules at 17 mol % PEGMA with ATRP, whereas conventional free‐radical polymerization required 24 mol % PEGMA to form capsules. The lower PEGMA level required for capsule formation with ATRP was attributed to the lower rates of propagation and crosslinking and to improved incorporation of PEGMA into the final gels. Suspension ATRP with 24 mol % PEGMA in the feed gave two‐layer capsule walls consisting of an inner layer visible by transmission electron microscopy and an outer layer visible by both transmission electron microscopy and environmental scanning electron microscopy, which indicated a compositional gradient across the capsule wall. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 156–171, 2006

Preparation of multihollow polystyrene particles by seeded emulsion polymerization using seed particles with incorporated nonionic emulsifier: effect of temperature

“…They can also potentially be used as microcapsules for controlled and sustained drug delivery systems [6][7][8] in the pharmaceutical industry. Various techniques for the preparation of such particles have been proposed [9][10][11][12][13][14][15][16][17]. One of the earliest approaches to prepare submicron-sized hollow polymer particles is based on osmotic swelling [18,19].…”

Gelation and Hollow Particle Formation in Nitroxide‐Mediated Radical Copolymerization of Styrene and Divinylbenzene in Miniemulsion

“…[59] To the best of our knowledge, the present work constitutes the first example of formation of hollow particles in a dispersed NMP process (Figure 8c). Hollow particle synthesis has previously been reported using ATRP [60,61] and RAFT. [62][63][64][65][66] The present results demonstrate that the SaPSeP method is applicable also to NMP systems, thus providing a convenient synthetic route to hollow polymer particles with a shell of comprising crosslinked polymer of high network homogeneity.…”

Synthesis of crosslinked poly(butyl methacrylate‐co‐pentaerythritol triacrylate) gel by single electron transfer‐living radical polymerization and its oil‐absorbing properties

“…During the FRP process, the slow initiation, fast chain propagation, and termination reactions result in the number of “dead” polymer chains increasing with time. Because of the dilute solution on the early stage, polymers of full length generate intramolecular crosslinking instead of overlapping each other, and then such chains are crosslinked together to form large molecules simultaneously absorbing more chains to produce microgels 10–22. This is undesired for ideal homogeneous polymer networks.…”

“…Single electron transfer‐living radical polymerization (SET–LRP),23–30 as well as other types of controlled/LRP12,13,16,18 has advantages over conventional FRP for synthesis of homogeneous polymer structures. In SET–LRP, the activation of dormant chains occurs via a heterolytic carbon halide bond cleavage catalyzed by a heterogeneous Cu(0) outer sphere SET.…”