Date of Award

Spring 1-1-2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

Jerry Qi

Second Advisor

Yifu Ding

Third Advisor

Martin Dunn

Fourth Advisor

Robert McLeod

Abstract

The motivation for this research was to demonstrate the ability to program the deformation of light activated polymers (LAPs) by controlling the chemical makeup, the mechanical parameters of the test, and the optical stimulus. The deformation of LAPs is a product of the network reformation that occurs due to the initiation of the Radical-Mediated Additional Fragmentation Chain Transfer (RAFT) mechanism. The RAFT mechanism minimizes the free energy present in the system, which can result in a localized plastic deformation under certain experimental parameters.

Tests were done to demonstrate the ability of controlled surface patterning and out of plane bending by manipulating this RAFT mechanism. Surface patterning was exhibited by initiating the RAFT mechanism in localized regions of an optically thin sample under some strain. To demonstrate bending, “optically thick” samples were used to create a gradient of network reformation, and thereby curvature. In addition to creating deformation, the objective of this work included predicting and prescribing surface features through control and modification of the testing parameters. To assist in this work, an FEA model was constructed in ABAQUS that effectively predicted the deformation caused by imposed values of applied strain, region of irradiation and maximum stress relaxation potential.

This study showed that by sufficiently characterizing the network rearrangement of optically thin and optically thin photoactive polymers, the deformation behavior could be predicted and controlled. In the optically thin case, this translates into precise control of surface patterning through the use of physical masks to define irradiation zones. In the optically thick case, tests illustrated that by using multiple prescribed irradiation steps based on the characterization studies, appropriate testing procedures could be defined to create bending out of plane. This work ultimately demonstrated the versatility of the deformation possible in LAPs.

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