Maurer, Marta Kamenjicki
(2004)
PHOTORESPONSIVE POLYMERIZED CRYSTALLINE COLLOIDAL ARRAYS AND CHEMICAL SENSORS.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The focus of this thesis is the development of novel materials based upon a self-assembled array of highly charged, monodisperse colloidal particles, called a crystalline colloidal array (CCA). We have developed a method to permanently lock the order of the CCA by embedding the CCA into a polymer network (PCCA). The polymer around the CCA can be functionalized with some recognition element, making these materials useful as optical sensors. This thesis describes a novel method for functionalizing PCCAs. We have successfully incorporated crown ethers and enzymes into PCCAs. The described method opens up the possibility of easy attachment of molecules containing amine, thiol and hydroxyl groups to PCCAs. The work includes incorporation of glycidyl methacrylate to the hydrogel network, and reacting the epoxide groups to develop sensing materials.This thesis also describes the fabrication of a new photochemically controlled PCCA. This photoswitchable device shows a photoreversible shift in diffracted light, and acts as a novel recordable and erasable memory device. The photoresponsive PCCA was created by functionalizing a PCCA with an azobenzene-type molecule. Gradual red-shifting of the diffraction peak upon UV illumination is accompanied by a decrease in p->p* absorption, and an increase in n->p* absorption, due to the trans->cis isomerization of azobenzene. Excitation with visible light results in the reverse cis->trans isomerization and a diffraction peak blue-shift to the original position. Information can be written using UV light and stored until visible light is used for erasing. An additional route for developing a photoresponsive PCCA is to introduce photochemical crosslinks inside the hydrogel network around the CCA. For this purpose we have used azophenyl-p-N,N'-dimaleimide. In contrast to the previously described photoresponsive PCCA, in which the hydrogel volume increases under UV irradiation, the azobenzene-crosslinked PCCA's volume decreases under UV light. Both systems are controlled by free energy of mixing.Different photochemically responsive PCCAs were created using a spiropyran derivative and different methods of attachment. These photochromic films are able to respond to UV and visible light by shifting the diffracted wavelength from the photosensitive film. The photochromic systems based on azobenzene and spiropyran described in this work could find wide technological applications in the future.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
| Title | Member | Email Address | Pitt Username | ORCID |
|---|
| Committee Chair | Asher, Sanford | asher@pitt.edu | ASHER | | | Committee Member | Schafmeister, Christian | | | | | Committee Member | Finegold, David | David.Finegold@chp.edu | | | | Committee Member | Waldeck, David | | | |
|
| Date: |
25 June 2004 |
| Date Type: |
Completion |
| Defense Date: |
22 April 2004 |
| Approval Date: |
25 June 2004 |
| Submission Date: |
3 May 2004 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Faculty of Arts and Sciences > Chemistry |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
azobenzene; crystalline colloidal array; photonic crystal; photoresponsive polymer |
| Other ID: |
http://etd.library.pitt.edu/ETD/available/etd-05032004-192343/, etd-05032004-192343 |
| Date Deposited: |
10 Nov 2011 19:43 |
| Last Modified: |
15 Nov 2016 13:43 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/7767 |
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