USING STEADY STATE AND TIME RESOLVED RAMAN SPECTROSCOPY TO STUDY THE VOLUME PHASE TRANSITION MOLECULAR MECHANISM OF POLY(N-ISOPROPYLACRYLAMIDE)

Wu, Tsung-Yu (2017) USING STEADY STATE AND TIME RESOLVED RAMAN SPECTROSCOPY TO STUDY THE VOLUME PHASE TRANSITION MOLECULAR MECHANISM OF POLY(N-ISOPROPYLACRYLAMIDE). Master's Thesis, University of Pittsburgh. (Unpublished)

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Abstract

Thermo-responsive hydrogels undergo volume phase transition (VPT). The temperature responsive VPT can be utilized for preparation of ‘smart’ materials. An ideal smart responsive material (SRM) would be triggered by a slight chemical or environmental change and respond in a desirable and reproducible way. Cross-linked Poly(N-isopropyl)acrylamide (PNIPAM) has one of the largest and fastest VPT, exhibiting a volume difference up to 30 fold within 1µs when temperature increases past the lower critical solution temperature (LCST). As a result, PNIPAM is a great candidate for developing SRM. However, even though PNIPAM is the most widely studied thermal responsive polymer, a deep understanding of the molecular mechanisms involved in the VPT is still lacking.

Our previous study found the time constant for dehydration of the amide group during VPT to be ~360 ns. In this study, a visible temperature jump (T-jump) Raman spectroscopy was constructed to monitor vibrational frequency of the isopropyl group and methylene backbone within PNIPAM during VPT. We found the VPT molecular mechanism occurs as the following: As the temperature elevates, the dehydration of the isopropyl groups occurs very quickly with a time constant ~68 ns, shortly after it is the dehydration of the polymer chains with a time constant ~104 ns. Finally, the dehydration of the amide group with a time constant ~ 360 ns.

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Details

Item Type:	University of Pittsburgh ETD
Status:	Unpublished
Creators/Authors:	Creators Email Pitt Username ORCID Wu, Tsung-Yu tsw26@pitt.edu tsw26
ETD Committee:	Title Member Email Address Pitt Username ORCID Committee Chair Asher, Sanford A. asher@pitt.edu ashher Committee Member Waldeck, David dave@pitt.edu dave Committee Member Garrett-Roe, Sean sgr@pitt.edu sgr
Date:	23 September 2017
Date Type:	Publication
Defense Date:	15 December 2016
Approval Date:	23 September 2017
Submission Date:	14 August 2017
Access Restriction:	1 year -- Restrict access to University of Pittsburgh for a period of 1 year.
Number of Pages:	67
Institution:	University of Pittsburgh
Schools and Programs:	Dietrich School of Arts and Sciences > Chemistry
Degree:	MS - Master of Science
Thesis Type:	Master's Thesis
Refereed:	Yes
Uncontrolled Keywords:	polymer, PNIPAM, VPT, volume phase transition, thermal responsive polymer, molecular mechanism, poly(N-isopropyl)acylamide, Raman spectroscopy
Date Deposited:	23 Sep 2017 22:46
Last Modified:	23 Sep 2018 05:15
URI:	http://d-scholarship.pitt.edu/id/eprint/33102

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• USING STEADY STATE AND TIME RESOLVED RAMAN SPECTROSCOPY TO STUDY THE VOLUME PHASE TRANSITION MOLECULAR MECHANISM OF POLY(N-ISOPROPYLACRYLAMIDE). (deposited 23 Sep 2017 22:46) [Currently Displayed]

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