https://web.itu.edu.tr/okayo/pdf/00review.pdf

Macroporous copolymer networks

A method is developed to enable emulsion polymerization to be performed under RAFT control to give living character without the problems that often affect such systems: formation of an oily layer, loss of colloidal stability, or loss of molecular weight control. Trithiocarbonate RAFT agents are used to form short stabilizing blocks from a water-soluble monomer, from which diblocks can be created by the subsequent polymerization of a hydrophobic monomer. These diblocks are designed to self-assemble to form micelles. Polymerization is initially performed under conditions that avoid the presence of monomer droplets during the particle formation stage and until the hydrophobic ends of the diblocks have become sufficiently long to prevent them from desorbing from the newly formed particles. Polymerization is then continued at any desired feed rate and composition of monomer. The polymer forming in the reaction remains under RAFT control throughout the polymerization; molecular weight polydispersities are generally low. The number of RAFT-ended chains within a particle is much larger than the aggregation number at which the original micelles would have self-assembled, implying that in the early stages of the polymerization, there is aggregation of the micelles and/or migration of the diblocks. The latexes resulting from this approach are stabilized by anchored blocks of the hydrophilic monomer, e.g., acrylic acid, with no labile surfactant present. Sequential polymerization of two hydrophobic monomers gives completely novel core-shell particles where most chains extend from the core of the particles through the shell layer to the surface.

Ab initio emulsion polymerization by RAFT-controlled self-assembly

Reactive polymers play many roles, from supports for solid-phase synthesis or catalysis to media for separations. Although macroporous polymer beads that provide high reactive capacities and excellent solvent tolerance are well established, approaches to monosized beads with optimized pore structures or multiple chemistries segregated within pores of different sizes have expanded their realm of application. Polymer monoliths containing intricate pore networks can be obtained in any desired shape by a simple molding process and provide unique advantages such as fast kinetics, high reactivity, and high throughput. Applications ranging from immobilized enzyme reactors to fast media for the separation of synthetic or biopolymers are presented.

https://science.sciencemag.org/content/sci/273/5272/205.full.pdf

New designs of macroporous polymers and supports : From separation to biocatalysis

A methodological description of heterogeneous polymerization processes, including suspension, emulsion, dispersion, and precipitation polymerization is presented. The discussion focuses on the initial state of the polymerization mixture, mechanism of particle formation, and the shape and size of polymer particles produced in different heterogeneous polymerization systems. The dependence of particle size and morphology on manufacturing parameters such as emulsifier, stabilizer, reactor design, and stirring speed is discussed. Special topics, including emulsifier-free (soapless) emulsion polymerization, seeded ponymerization, and the formation of core-shell particles are also briefly covered.

Suspension, emulsion, and dispersion polymerization : a methodological survey

Preparation and application of new monosized polymer particles

Monodisperse porous polymer particles in the size range of 10 μm in diameter were prepared via seeded emulsion polymerization. Linear polymer (polystyrene seed) or a mixture of linear polymer and solvent or nonsolvent were used as inert diluents. The pore diameters of these porous polymer particles were on the order of 1000 A with pore volumes up to 0.9 mL/g and specific surface areas up to 200 m2/g. The physical features of the porous polymer particles depended on the diluent type and the crosslinker content, as well as the molecular weight of polymer seed particles. By varying the molecular weight of the linear polymer, monodisperse porous polymer particles with different pore size distribution could be synthesized. Polymer seed with a low degree of crosslinking instead of linear polymer could also be used to prepare monodisperse porous polymer particles with smaller pore volume and pore size.

Synthesis and characterization of monodisperse porous polymer particles

Monodisperse polystyrene latexes are prepared by seeded emulsion polymerization; however, sizes larger than 2 microns are difficult to prepare because of the creaming and settling of the particles and their sensitivity to mechanical shear. Preparation in space would obviate the creaming and settling, and allow agitation just sufficient for good heat transfer and mixing. Three polymerizations yielding 3-5 micron size particles were carried out successfully on the third flight of the 'Columbia' launched Mar. 22, 1982; however, four polymerizations yielding sizes up to 10 microns on the fourth flight launched June 27, 1982 were incomplete owing to apparatus malfunction. The results of these polymerizations and the prospects of developing a preparative space process are reviewed.

Preparation of large-particle-size monodisperse latexes in space: polymerization kinetics and process development

Dynamic Surface Tension Measurement with a Dynamic Wilhelmy Plate Technique

Monodisperse latexes having a particle size in the range of 2 to 40 microns are prepared by seeded emulsion polymerization in microgravity A reaction mixture containing smaller monodisperse latex seed particles, predetermined amounts of monomer, emulsifier, initiator, inhibitor and water is placed in a microgravity environment, and polymerization is initiated by heating The reaction is allowed to continue until the seed particles grow to a predetermined size, and the resulting enlarged particles are then recovered A plurality of particle-growing steps can be used to reach larger sizes within the stated range, with enlarged particles from the previous steps being used as seed particles for the succeeding steps Microgravity enables preparation of particles in the stated size range by avoiding gravity-related problems of creaming and settling, and flocculation induced by mechanical shear that have precluded their preparation in a normal gravity environment

Process for preparation of large-particle-size monodisperse

Monodisperse latexes of at least 2-30 microns particle size are prepared from an emulsion recipe comprising a monodisperse seed latex polymer on the order of 2 microns or less particle size, a polymerizable monomer, an initiator, at least one inhibitor, and a water-soluble polymeric emulsifier of 104 -107 molecular weight. Optional ingredients are crosslinking monomer, oil-soluble inhibitor if the mixture is to be stored before polymerization, and one or more additional emulsifiers selected from a water-soluble comonomer or polymer of 0.3×103 -5×103 molecular weight and a non-polymeric anionic emulsifier. Additional particle size growth and monodisperse latex yield are realized by polymerization in a microgravity environment.

F. J. Micale

Papers

Synthesis and characterization of monodisperse porous polymer particles

Preparation of large-particle-size monodisperse latexes in space: polymerization kinetics and process development

Dynamic Surface Tension Measurement with a Dynamic Wilhelmy Plate Technique

Process for preparation of large-particle-size monodisperse

Preparation of large particle size monodisperse latexes