Water-borne coatings have increased in popularity due to the recent environmental regulations being placed on coating formulation. The most readily available coatings without volatile organic compounds are thermoplastic polymer dispersions that rely on interdiffusion to form a film. These dispersions are reliant on toxic crosslinking chemistries to achieve adequate coating mechanical properties, but still have significantly inferior properties when compared with current thermosetting industrial coatings that contain volatile organic compounds. As a result, waterborne coatings made with conventional emulsion polymers cannot be considered for high-performance coatings. Polyurethane dispersions have been developed that can meet these demands, but require several lengthy coating applications and are therefore incredibly costly. A water-based acrylic emulsion polymer coating that could self-stratify and apply multiple crosslinkable layers simultaneously, has the potential to revolutionize current coating formulations. Recent advances in anisotropic polymer colloid synthesis offer a potential pathway to make such a high-performance coating. Incorporating unique functionality into each of the lobes of a bilobal particle would enable the formation of a new class of water-based, self-stratifying, high-performance, acrylic coatings. The primary goal of this thesis was to show proof of concept for a bilobal platform that could be used to form water-based self-stratifying coatings. The approach was adapted from recent advances in pigment-associating emulsion polymers used to improve coating pigment dispersion. Butyl acrylate and methyl methacrylate seed particles ~90 nm in size were formed and subsequently used to synthesize preliminary ~130 nm acrylic bilobal particles, within the target size range of water based coating dispersions. Control over the seed particle glass transition temperature, size, and morphology, and synthesis of promising preliminary bilobal particles was demonstrated; this was accomplished using a systematic analysis of various reaction conditions, namely, pre-emulsification, reaction duration, and the concentrations of the monomers. Expanding upon the chemical versatility would enable these particles to be used in a wide variety of applications, but this thesis represents a promising start for the bilobal platform within the coating industry.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:masters_theses_2-2200 |
| Date | 20 October 2021 |
| Creators | Tillinghast, Guinevere E |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Masters Theses |
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