Miniemulsion Polymerization with Arrested Ostwald Ripening Stabilized by Amphiphilic RAFT Copolymers

Pham, Binh T.T.; Zondanos, Hollie S.; Such, Christopher H.; Warr, Gregory G.; Hawkett, Brian S.

doi:10.1021/ma101087t

Cited by 35 publications

(45 citation statements)

References 38 publications

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“…This helps explain why the molar mass decreases consistently as function of the DMAEMA reversible protonation, for both nonliving and RAFT conditions. Moreover, M w / M n > 1.5 are normally reported for RAFT polymerization in dispersed systems, revealing the challenge to obtain narrow distributions in such processes. In addition to the possible slow activation of the RAFT‐CTA, deviations of the MMDs are also in part related to monomer diffusion as function of pH, its retention in the dispersed aqueous phase (monomer‐swollen micelles), and consequentially changes in the M/CTA ratio at the polymerization loci.…”

Section: Resultsmentioning

confidence: 98%

RAFT Inverse Microemulsion Polymerization: Effects of Monomer Solubility and Different Types of Initiators

Oliveira

2017

Macro Reaction Engineering

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The effects of monomer solubility and different types of initiators are for the first time reported for a reversible addition–fragmentation chain transfer (RAFT) inverse microemulsion polymerization system. 2‐(dimethylamino)ethyl methacrylate is selected as monomer due to its solubility in several solvents. A nonionic surfactant, cyclohexane, and a trithiocarbonyl RAFT chain transfer agent (CTA) are also used as main components. The reactions are performed adjusting the dispersed aqueous phase with selected pH values (5, 7, and 10), using an oil‐soluble or a water‐soluble initiator. In this microemulsion system, the RAFT process is especially influenced by the monomer content in the dispersed aqueous phase, directly related to the final pH. It is suggested that monomer diffusion and changes in the monomer/CTA ratio at the polymerization loci are the primary reasons for the different behaviors observed, specially those related to the molar mass properties.

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Section: Resultsmentioning

confidence: 98%

RAFT Inverse Microemulsion Polymerization: Effects of Monomer Solubility and Different Types of Initiators

Oliveira

2017

Macro Reaction Engineering

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“…Our previous studies showed that polymerization using these diblocks under similar conditions were under RAFT control. 28,29 The particle size and size distribution of the micelles and PSty seeds by DLS and HDC is presented in Table 1. The HDC particle sizing method is based on the principle of chromatography that the smaller particles are eluted after the bigger ones.…”

Section: Discussionmentioning

confidence: 99%

“…The method has been described previously. 26,28,29 Synthesis of amphiphilic macro-RAFT agents Synthesis of amphiphilic macro-RAFT diblock: RAFT-Sty 20 -b-AA 14 . Acrylic acid and styrene were polymerized in the presence of PABTC, in dioxane, to yield an amphiphilic diblock copolymer (Scheme 1B).…”

Section: Methodsmentioning

confidence: 99%

Synthesis of polymeric janus nanoparticles and their application in surfactant-free emulsion polymerizations

Pham

Such²,

Hawkett

2015

Polym. Chem.

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A robust and simple synthesis of nano-size oblate to dumbbell shaped polymeric anisotropic particles using RAFT mediated emulsion polymerization is presented. The particle synthesis relies on the property that monomer swollen cross-linked polymer seed particles shrink and expel some of the monomer when heated. Thus, upon heating for polymerization, some of the swelling monomer is expelled and subsequently polymerizes to form a bulge on the side of the original crosslinked seed particle. The shape of the bulge, and the degree of contact that the expelled monomer maintains with the original seed particle, is controlled by controlling the wettability of the seed surface by the expelled monomer. Very small monodisperse cross-linked polymer particles are initially prepared by RAFT mediated emulsion polymerization, then swollen with monomer and further polymerized to form anisotropic particles with a long dimension as little as 25 nm. Both the shape of the anisotropic bulge and the polymer composition, of each end of the final Janus nanoparticle can be finely controlled. The surface active properties of the Janus nanoparticles are demonstrated by their ability to contribute as stabilizers and influence particle formation in a surfactant free ab-initio emulsion polymerization. The method provides a simple and reproducible process for the production of Janus colloidal nanoparticles readily achievable in a normal latex plant where batch size would be limited only by the size of the reactor.

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“…stability. Of particular interest is the fact that Ostwald ripening is arrested for block copolymer stabilized aqueous emulsion, as shown recently by Pham et al 36…”

Section: Non‐polymerizable Oil‐in‐oil Emulsionsmentioning

confidence: 99%

Block copolymers as polymeric stabilizers in non‐aqueous emulsion polymerization

Atanase

Riess

2011

Polymer International

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This review summarizes the background and recent advances of block copolymer stabilized oil‐in‐oil emulsions. For non‐polymerizable emulsions which have promising application possibilities for biomedical and cosmetic formulations, it is shown that tailor‐made block copolymers are by far the most efficient stabilizers with respect to low molecular weight surfactants. The characteristic features of oil‐in‐oil emulsions comprising one polymerizable phase are described. These types of non‐aqueous emulsions are of interest as nanoreactor systems for the polymerization of moisture‐sensitive monomers or catalysts. Furthermore they are the starting point of novel heterophase polymerization processes for the preparation of sterically stabilized polymer particles, as well as of ‘liquid‐filled polymeric materials’. The concept of oil‐in‐oil emulsions is finally extended to those systems where the two phases are polymerizable by distinct polymerization mechanisms. This approach could offer attractive possibilities for the development of special coatings with neither water nor solvent evaporation in their drying or curing step. Copyright © 2011 Society of Chemical Industry

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Miniemulsion Polymerization with Arrested Ostwald Ripening Stabilized by Amphiphilic RAFT Copolymers

Cited by 35 publications

References 38 publications

RAFT Inverse Microemulsion Polymerization: Effects of Monomer Solubility and Different Types of Initiators

RAFT Inverse Microemulsion Polymerization: Effects of Monomer Solubility and Different Types of Initiators

Synthesis of polymeric janus nanoparticles and their application in surfactant-free emulsion polymerizations

Block copolymers as polymeric stabilizers in non‐aqueous emulsion polymerization

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