Photochemical Sciences Ph.D. Dissertations

Title

Tailoring Biomass for Light Active Compounds and Materials

Date of Award

2020

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Photochemical Sciences

First Advisor

Jayaraman Sivaguru (Advisor)

Second Advisor

Yan Wu (Other)

Third Advisor

Malcolm D.E. Forbes (Committee Member)

Fourth Advisor

Alexander Tarnovsky (Committee Member)

Abstract

Understanding the facts of decreasing in availability of non-renewable fossil fuels, and increase in demand for new renewable sources, many efforts across the world have been put forward for converting biomass especially carbohydrates and lignin into eco-friendly materials Biomass not only give a greener perspective but also, they are inexpensive; abundant in nature and most importantly they are renewable. By merging the concepts of polymer, organic and photochemistry, one can transform biomass in to photoresponsive materials. The importance and synthesis of biobased polymers, principles of green chemistry and the effects of plastic pollution, were introduced in chapter 1. In addition to biobased materials, some fundamental concepts of photochemistry, photoprotecting groups (PPGs), different types of photoinitiators were also included.

Second chapter details some of the polymer degradation pathways and their limitations were highlighted. This chapter mainly focus on photoresponsive polymeric/oligomeric materials derived from biomass. The fundamental concepts of phototriggers were utilized in designing and evaluating polymers and degradability at ~ 300nm. Synthesis and characterization of polymers were reported by employing various methods. A detailed photochemical and photophysical studies were carried out to support the mechanism.

Chapter three describes about synthesis of novel photoinitiators for visible light mediated polymerization. The novel photoinitiators were evaluated for photopolymerization of acrylate monomers under blue LED irradiation. UV-Vis absorption studies for photoinitiators and gel permeation chromatography analysis for polymers were studied. The strategy developed in this chapter highlights the role of solvent as co-initiator and formation of polymers without photoinitiator leaching.

Chapter four details about synthesis and evaluation of biomass derived photoinitiators for type II photopolymerization. In order to understand the nature of photoinitiator excited states, role of co-initiators, photochemical and photophysical studies were performed. Biomass derived furan acrylates were synthesized for photopolymerization. Our biobased photoinitiators can be used as potential replacements for industrially employed benzophenones that are derived from petroleum feedstocks.

Chapter five describes synthesis and evaluation of biomass derived photoinitiators for type I polymerization. These novel biomass derived photoinitiators were made active in the visible region that has the potential to enhance depth of light penetration for curing applications (e.g. paints/ coatings etc..).

Chapter six evaluates new photochemical systems for intermolecular [2+2] photocycloaddition aiming the formation of azetidine products.

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