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Self-Stratifying Coatings

Alyamac, Elif
http://rave.ohiolink.edu/etdc/view?acc_num=akron1259474985

Abstract Details

2009, Doctor of Philosophy, University of Akron, Polymer Engineering.
The goal of this dissertation was to develop a self-stratified/gradient two-phase coating system. The most promising systems comprised of epoxide and acrylic were taken into consideration. The first part of the research focused on synthesizing and evaluating a series of acrylate-based surface-active copolymers (phase-A), and inorganic modified epoxide derivatives (phase-B) which would function as topcoat and primer coat respectively. A series of low, medium, and high molecular weight copolymers containing methyl methacrylate, n-butyl acrylate, 2-hydroxyethyl methacrylate, and 2,2,2-trifluoroethyl methacrylate was synthesized by solution polymerization under monomer-starved conditions. The acrylate-based copolymers were characterized by FTIR; 1H, 13C, and 19F NMR, and MALDI-TOF mass spectrometry. The copolymers were crosslinked with a methylated melamine formaldehyde resin in order to obtain thermosetting acrylics. An enrichment of fluorinated units at the acrylic surface was directly verified measuring dynamic contact angles. The bisphenol-A based epoxide was modified by unsaturated fatty acid, phosphoric acid, and tetraethylorthosilicate (TEOS) oligomer, prepared through the hydrolysis and condensation of TEOS monomer with water under acidic condition. The coating performance and the viscoelastic properties of the hybrid systems were evaluated as a function of polysilicate content. Salt spray analysis revealed that inorganic modified epoxide derivatives provided improvement over commercial epoxide resin by substantially improving the corrosion resistance, as well as providing better adhesion to steel substrates. The second part of the research investigated the driving forces that transform a quasi-stable homogeneous mixture of a two-phase coating system into a stratified one. Hansen’s three-dimensional solubility parameters were used to characterize oligomer-solvent interaction. The solubility of the oligomers was evaluated in a set of 30 different solvents of which Hansen solubility parameters are known. A nonlinear unconstrained optimization technique was proposed to estimate Hansen’s dispersion, polar and hydrogen bonding solubility parameters for the oligomers. A quasi-stable homogeneous mixture of two immiscible oligomers dissolved in a common solvent was applied as a thin film. During simultaneous chemical crosslinking and solvent evaporation, the formation of self-stratified/gradient two-phase coatings was investigated. The films were evaluated via X-ray Photoelectron Spectroscopy (XPS) on the air-film and film-substrate interfaces. The fluorine in acrylic and the silicon in epoxide were convenient markers for the XPS study. As a complementary technique to the XPS, Environmental Scanning Electron Microscopy (ESEM) with integrated Energy Dispersive Spectroscopy (EDS) provided valuable information on the degree of stratification via chemical analysis and imaging on the cross-section of the coatings. It was found that increasing the fluorine content in acrylic phase, using low molecular weight acrylics, and modifying epoxide with TEOS led to a clear self-organization. Immiscibility of the phases facilitated the stratification. Successful self-stratified coating systems illustrated favorable surface, viscoelastic, and coating properties. As a conclusion, the promising results of the research show potential commercialization implications.
Mark D. Soucek, PhD (Advisor)
293 p.
Chemistry; Plastics; Polymers

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Citations

  • Alyamac, E. (2009). Self-Stratifying Coatings [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1259474985

    APA Style (7th edition)

  • Alyamac, Elif. Self-Stratifying Coatings. 2009. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1259474985.

    MLA Style (8th edition)

  • Alyamac, Elif. "Self-Stratifying Coatings." Doctoral dissertation, University of Akron, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1259474985

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Akron and OhioLINK.