SMALL ANGLE X-RAY SCATTERING AND RHEOLOGY STUDIES OF POLYISOBUTYLENE WITH OLIGO(ß-ALANINE) GRAFTS

SMALL ANGLE X-RAY SCATTERING AND RHEOLOGY STUDIES OF POLYISOBUTYLENE WITH OLIGO(ß-ALANINE) GRAFTS

Bibliographic Details
Main Author: Zhao, Wenhan, ZHAO
Language:English
Published: University of Akron / OhioLINK 2018
Subjects:
Polymers
Morphology
Materials Science
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=akron1528983070278315
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spelling ndltd-OhioLink-oai-etd.ohiolink.edu-akron15289830702783152021-08-03T07:07:10Z SMALL ANGLE X-RAY SCATTERING AND RHEOLOGY STUDIES OF POLYISOBUTYLENE WITH OLIGO(ß-ALANINE) GRAFTS Zhao, Wenhan, ZHAO Polymers Morphology Materials Science Thermoplastic elastomers are used in various applications due to their outstanding mechanical performance. Here we consider three different polymers which have the same polyisobutylene main chain with side chains of oligo ß-alanine (PIB-g- ßA3). The ß-alanine units self-associate via hydrogen bonds into nanocrystals containing a ß-sheet secondary structure. In previous studies, the contributions of hydrogen bonding and a chain stretching entropy penalty have been studied. Based on that, here three different graft structures are considered for controlling the nanocrystal sizes: one with an eleven-carbon spacer between the backbone and oligo ß-alanine, one with an eleven-carbon spacer and a phenyl group and one with no spacer and a seventeen-carbon tail on the other end of the oligo ß-alanine.We investigate the structure of the microphase separation and crystallization with combined Small Angle X-ray Scattering and Wide Angle X-ray Scattering which are sensitive to size of the structure. All three polymers have quite small crystalline nanodomains in a matrix at room temperature. When increasing temperature, the nanocrystals melt and the well-defined microphase separation is lost. Rheology studies run upon cooling show that the storage modulus of the polymer with graft tails but no phenyl group increases quite gradually with decreasing temperature, because the ability of the ß-alanine units to order is hampered by the need for both the graft tail and parts of the PIB backbones to stretch for ordering to occur. The polymer with a spacer separating the ß-alanine units from the main chain, but no phenyl group or tails on the graft, shows the sharpest transition, highest transition temperature and the highest modulus in the ordered state, because the spacer means less constraint of the chain movement needed for ordering. The third polymer with a spacer, but also a phenyl group between the ß-alanine units and the spacer, orders similarly, but slightly less readily and has an ordered structure with slightly larger domains. 2018-06-14 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1528983070278315 http://rave.ohiolink.edu/etdc/view?acc_num=akron1528983070278315 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection NDLTD
language English
sources NDLTD
topic Polymers
Morphology
Materials Science
spellingShingle Polymers
Morphology
Materials Science
Zhao, Wenhan, ZHAO
SMALL ANGLE X-RAY SCATTERING AND RHEOLOGY STUDIES OF POLYISOBUTYLENE WITH OLIGO(ß-ALANINE) GRAFTS
author Zhao, Wenhan, ZHAO
author_facet Zhao, Wenhan, ZHAO
author_sort Zhao, Wenhan, ZHAO
title SMALL ANGLE X-RAY SCATTERING AND RHEOLOGY STUDIES OF POLYISOBUTYLENE WITH OLIGO(ß-ALANINE) GRAFTS
title_short SMALL ANGLE X-RAY SCATTERING AND RHEOLOGY STUDIES OF POLYISOBUTYLENE WITH OLIGO(ß-ALANINE) GRAFTS
title_full SMALL ANGLE X-RAY SCATTERING AND RHEOLOGY STUDIES OF POLYISOBUTYLENE WITH OLIGO(ß-ALANINE) GRAFTS
title_fullStr SMALL ANGLE X-RAY SCATTERING AND RHEOLOGY STUDIES OF POLYISOBUTYLENE WITH OLIGO(ß-ALANINE) GRAFTS
title_full_unstemmed SMALL ANGLE X-RAY SCATTERING AND RHEOLOGY STUDIES OF POLYISOBUTYLENE WITH OLIGO(ß-ALANINE) GRAFTS
title_sort small angle x-ray scattering and rheology studies of polyisobutylene with oligo(ß-alanine) grafts
publisher University of Akron / OhioLINK
publishDate 2018
url http://rave.ohiolink.edu/etdc/view?acc_num=akron1528983070278315
work_keys_str_mv AT zhaowenhanzhao smallanglexrayscatteringandrheologystudiesofpolyisobutylenewitholigoßalaninegrafts
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