Photochemical Sciences Ph.D. Dissertations

Title

Design, synthesis, and characterization of photoresponsive materials using coordination bonds and other supramolecular interactions

Date of Award

2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Photochemical Sciences

First Advisor

Alexis Ostrowski (Advisor)

Second Advisor

Scott Rogers (Committee Member)

Third Advisor

Alexander Tarnovsky (Committee Member)

Fourth Advisor

R. Marshall Wilson (Committee Member)

Abstract

When designing light-responsive, healable materials and adhesives, these materials need to include controllable reversible, bonding interactions. Such dynamic interactions are difficult to control, however. In this work, we present how these interactions can be controlled by incorporating photoactive metal ions into supramolecular polymer network what allow the tuning of optical and mechanical properties of the polymers with light.

Utilizing this approach, we created a series of supramolecular polymer melts and studied their mechanical and photo physical properties. We have shown that the photochemistry and photophysical properties of the metal center can be used to control the mechanical properties of the materials, and introduce new optical and mechanical properties not seen in the traditional covalent polymers. In particular, photo-induced metal-ligand bond labilization led to partial depolymerization of the supramolecular assembly, and softening of the materials. When the light stimulus was removed, the material recovered the initial stiffness back. We also investigated structure-property relationships in such systems where mechanical properties of the supramolecular polymers are controlled by coordination environment around metal cross-linking center.

We also considered how polymer host matrix impacts on the photophysical and photochemical properties of chromophores that undergo molecular motion in the exited state. In particular, change in excited state dynamics of [Cu(dmp)2]+ can be used to sense viscosity of various polymers. A linear dependence of excited state lifetime and emission wavelength on viscosity was correlated with restricted photoinduced structural distortion of Cu(I) complex in more flow-resistance media.

Link to Full Text
COinS