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Emulsion Polymers Consulting and Education
EPCEd is celebrating its 10th Anniversary! Thank you to all of you who helped to make our first decade so successful. We look forward to many more years of sharing our knowledge of emulsion polymers with you.
Introducing our first online workshop! It seems appropriate to start this new online format with a workshop that is being offered for the first time. Basics of Creating Latex Particles with Controlled Size and Chemistry (Step¹) is being presented on August 23-26. Click here for more information. Advertising has already begun, so those on our mailing list have already received detailed information about this workshop, and we are taking registrations. You can sign up for our mailing list on the Contact page. We will also be offering our popular Scale-up and Commercial Production of Emulsion Polymers (Step⁸) workshop at the end of October. Look for a mailing on this workshop soon. Mike and his co-author P. G. Jessop have a new book out. Jessop, P.G. and Cunningham, M.F.; CO2-Switchable Materials, The Royal Society of Chemistry, 2020. Here is a link to the abstract. EPCEd is now advertising in Coatings Tech, both in print and online. You can see our ad in the May issue, and more ads will appear throughout the year. EPCEd is now partnering with PCI magazine (the magazine of the Paint and Coatings Industry) to include some of our “Did You Know….?” series in their monthly issues. PCI magazine gives us an opportunity to share these popular bits of insight into the workings of emulsion polymerization with an even more diverse audience.
Abstract: Emulsion polymerization allows the creation of aqueous dispersions of polymer nanoparticles in the 50-500 nm size range and these products (synthetic latexes) have been made at commercial scales for nearly a century. In the latter half of that period there emerged a wide variety of nanoparticles composed of two, phase incompatible materials producing composite particles having a large number of morphological features. Among those are the so-called core-shell, occluded, multi-lobed, hollow and mixed structures. This has led to advanced materials serving markets for impact resistant plastics, architectural and industrial coatings, adhesives, low density opacifiers, printing inks, among others. As the need for such materials has grown, the chemical and physical mechanisms that control the development of particle structure have been substantially investigated and much progress has been made. The objective of the following discussion is to describe the scientific and engineering principles at play when creating these composite particles and to demonstrate how the balance of thermodynamic equilibrium conditions and kinetic limitations (chemical reaction and polymer chain diffusion) combine and/or compete to result in particular morphologies. Many examples are presented.
Sanders, Connor A.; George, Sean R.; Deeter, Gary A.; Campbell, J. D.; Reck, Bernd; Cunningham, Michael F. “Amphiphilic Block-Random Copolymers: Self-Folding Behavior and Stabilizer in Emulsion Polymerization”, Macromolecules (2019), 52, 4510-4519. DOI:10.1021/acs.macromol.9b00519.
Abstract: Polystyrene-b-[polystyrene-r-poly(acrylic acid)] block-random copolymers have been synthesized at various molecular weights (7,000–23,200 g/mol) and with compositions between 6–39 mol% acrylic acid by nitroxide-mediated polymerization. Emulsion polymerizations of styrene stabilized by block-random copolymers yielded stable latexes at stabilizer concentrations 3 wt% based on monomer. A series of emulsion polymerizations with varying stabilizer content suggests that a novel nucleation mechanism is occurring in block-random copolymer stabilized emulsion polymerizations, exhibiting distinctly different behavior from block copolymers or conventional small molecule surfactants. Moreover, alkaline aqueous dispersions of the block-random copolymers were prepared with ease up to concentrations of 300 g/L, whereas similar block copolymers are limited to ~1 g/L. Analysis of the dispersions via dynamic light scattering and atomic force microscopy suggest that single-chain nanoparticles form via a self-folding process with hydrodynamic diameters between 2.4 and 5 nm. The novel stabilizer structures may be tuned for rapid dispersion through their anchoring block [polystyrene] and high stabilization efficiency through the stabilizing block [polystyrene-r-poly(acrylic acid)].
Giudici, Reinaldo; Espinola, Magda; Cunningham, Michael. , Macromolecular Reaction Engineering (2019), 13, 1900009, DOI:10.1002/mren.201900009.
Abstract: Thermosensitive-thermochromic pigments are classified as smart materials capable of detecting and/or responding to environmental stimuli, and specifically in this study, changes in temperature that induce a change in the color of the material. This study aims to obtain nanoparticles of poly(styrene-co-butyl acrylate) and poly(styrene-co-methyl methacrylate), containing thermosensitive-thermochromic pigments that are incorporated into the monomer droplets in miniemulsion polymerization. Miniemulsion polymerization has the advantage that the pigment particles can be dispersed directly in the monomer droplets and are encapsulated when the miniemulsion droplets are polymerized. Using controlled/living radical polymerization (or Reversible Deactivation Radical Polymerization), it is possible to produce polymers with better control of microstructure and narrower molecular weight distributions. We conducted nitroxide mediated polymerization (NMP) using the BlocBuilder® initiator, as well as a conventional free radical polymerization (FRP) using potassium persulfate (KPS) and 2,2-azobis(2-methylpropionitrile) (AIBN). Stable latexes containing the thermosensitive-thermochromic pigments were obtained by both NMP and FRP. Films were made from the latexes and shown to exhibit thermochromic behavior.
Here is a list of recent publications by Don and Mike:
Sundberg, Donald, Structured, Composite Nanoparticles from Emulsion Polymerization – Morphological Possibilities, Biomacromolecules, (2020) 21(11), 4388-4395. DOI:10.1021/acs.biomac.0c00549.