Date of Award

Spring 2020

Project Type

Thesis

Program or Major

Chemistry

Degree Name

Master of Science

First Advisor

Erik Berda

Second Advisor

Arthur Greenberg

Third Advisor

Margaret Greenslade

Abstract

ABSTRACT

DIELS-ALDER FUNCTIONALIZED PARTICLES FOR MECHANICAL IMPROVEMENTS IN ADDITIVE MANUFACTURING

By

Elizabeth Sylvester

University of New Hampshire, May 2020

This thesis explores the use of Diels-Alder functionalized particles to aide in the mechanical enhancement of additively manufactured objects. To date, materials generated via additive manufacturing lack isotropic properties due to the nature in which they are created – in a layer by layer fashion. This methodology often leads to poor interfacial adhesion at the junction between printed layers, lowering the stability of the part and thereby limiting its use in many applications. Dynamic covalent chemistry, such as the reversible Diels-Alder reaction, has the ability to alleviate this anisotropy to print stronger, more uniform objects. To do so, this work investigates crosslinked, Diels-Alder functionalized particles generated by two separate methods: polymerization via reversible addition fragmentation chain transfer (RAFT) followed by atom transfer radical coupling (ATRC) and free radical emulsion polymerization. These particles can be blended with a polymeric filament for 3D printing, where upon heating during the extrusion process of additive manufacturing, the retro-Diels-Alder reaction is initiated and releases the crosslinked particles exposing reactive diene and dienophile pairs. In subsequent cooling after the printing process, these moieties undergo the forward Diels-Alder reaction and form chemical linkages between printed layers of the substrate to improve the mechanical integrity and uniformity of objects produced by means of additive manufacturing.

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