Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Cationic frontal polymerization broadens the potential application of frontal polymerization by allowing for use of monomers such as epoxies and vinyl ethers. In this work, the effects of monomer and initiator composition and additives including fillers on front kinetics, along with applications of cationic frontal polymerization were investigated.

Using a radical-induced cationic frontal polymerization (RICFP) method with a superacid generating salt and a thermal radical initiator, the addition of vinyl ethers to epoxy formulations was studied, where an increase of front velocity was seen with increase of divinyl ether to epoxy ratio. Other aspects of vinyl ether systems, such as pot life and functionality, were also investigated. With promising results of vinyl ethers, synthesis of novel vinyl ethers for frontal polymerization was attempted in Chapter 3. In Chapter 4, a hybrid system with the addition of acrylates, which have been well-studied in frontal polymerization, to epoxies and vinyl ethers was investigated, and it was demonstrated that the ratio of monomers can affect the material properties of polymers formed. The acrylates do not copolymerize with the epoxy or vinyl ether, resulting in a concave dependence of front velocity on acrylate percentage.

Adding fillers to formulations can improve mechanical properties, lower overall cost, and affect front velocity. In Chapter 5, clay minerals added to RICFP systems were found to reduce front velocity. Causes of this reduction were investigated, as were the effects of the fillers on mechanical and thermal properties of the polymer composites and clay dispersion in the polymer matrix. Drying the clays in an oven increased the front velocity, indicating water content inhibiting the cationic polymerization.

In a modification of RICFP presented in Chapter 6, it was found that a front was supported for epoxies and vinyl ethers in absence of a primary radical source and only addition of the superacid generator. The superacid generating salt acts as a source of radicals, as indicated by the addition of radical inhibitor. Potential applications investigated for RICFP are shown in Chapter 7, which includes additive manufacturing, coatings, and use of bio-derived monomers.

Date

10-18-2023

Committee Chair

Pojman, John

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