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Photopolymerization-Induced Crystallization in Relation to Solid-Liquid Phase Diagrams of Blends of Blends of Poly(ethylene oxide)/Multi-functional Acrylate Monomers

Park, Soo Jeoung
http://rave.ohiolink.edu/etdc/view?acc_num=akron1218131827

Abstract Details

2008, Doctor of Philosophy, University of Akron, Polymer Engineering.
The goal of the present dissertation is to elucidate of the phenomenon of photopolymerization-induced phase transition (PIPT) in order to provide guidance to the fabrication of polymer photonic crystals via photolithography. The phenomenon of photopolymerization-induced phase separation and crystallization is a phase transformation process driven by photochemical reaction, in which the phase ordering occurs during the photo patterning. Although the reaction-induced phase separation is well investigated, the photopolymerization-induced crystallization is new in this field. First, the solid-liquid phase diagrams of the starting blends of polyethylene oxide (PEO)/multi-functional acrylate monomers have been established by means of differential scanning calorimetry and optical microscope. It was found that the PEO/acrylate systems reveal various coexistence regions including isotropic (I), the coexistence of crystal + liquid (Cr1+L2) and the crystal + crystal (Cr1+Cr2) gaps. A phase field theory pertaining to the solid-liquid phase transition in conjunction with the Flory Huggins theory for liquid-liquid phase separation has been developed to test with these experimental phase diagrams. The aforementioned coexistence regions have been further verified experimentally by probing the spatio-temporal emergence of crystalline structure and phase morphology using time-resolved optical microscopy following several temperature-quenches into these individual coexistence regions. The effects of molecular weight of PEO and acrylate arm topology of acrylate monomers on their blend phase diagrams have been explored.Guided by these established phase diagrams of the PEO/multi-functional acrylate blends, photopolymerization-induced crystallization experiments have been carried out at the isotropic temperatures slightly above the depressed melting points of PEO crystals corresponding to the liquidus line. The depressed melting curve shifts upward to the elevated temperatures and eventually surpasses the reaction temperature which in turn drives the system into the unstable gap triggering the photopolymerization-induced crystallization. Various crystalline phase morphologies including development of spherulites in the continuum of the isotropic region were observed in the crystal + liquid coexistence region. At higher reaction temperatures, above the melting temperature, viscous fingering (or fractal growth) takes place during photopolymerization, showing phase separated domains within these advancing viscous fingering structures. Finally, the study was extended to holographic photopolymerization that allows the reaction to occur predominantly in high intensity regions to create periodic patterns. Of particular interest is the growth of the hierarchical structures of PEO crystals and two-phase morphology within the stripes or interconnected channels and/or arrays of spheres.
Thein Kyu (Advisor)
280 p.
Polymers
polymer blend; phase diagram; PEO; multi-functional acrylate; photopolymerization; crystallization

Recommended Citations

Citations

  • Park, S. J. (2008). Photopolymerization-Induced Crystallization in Relation to Solid-Liquid Phase Diagrams of Blends of Blends of Poly(ethylene oxide)/Multi-functional Acrylate Monomers [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1218131827

    APA Style (7th edition)

  • Park, Soo Jeoung. Photopolymerization-Induced Crystallization in Relation to Solid-Liquid Phase Diagrams of Blends of Blends of Poly(ethylene oxide)/Multi-functional Acrylate Monomers. 2008. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1218131827.

    MLA Style (8th edition)

  • Park, Soo Jeoung. "Photopolymerization-Induced Crystallization in Relation to Solid-Liquid Phase Diagrams of Blends of Blends of Poly(ethylene oxide)/Multi-functional Acrylate Monomers." Doctoral dissertation, University of Akron, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1218131827

    Chicago Manual of Style (17th edition)

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© 2008, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.