THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER

THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER

Bibliographic Details
Main Author: Liu, Boer
Language:English
Published: University of Akron / OhioLINK 2018
Subjects:
Polymers
Thin films
interfaces
branched polymer
immobile layer
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=akron1525261861391343
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spelling ndltd-OhioLink-oai-etd.ohiolink.edu-akron15252618613913432021-08-03T07:06:36Z THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER Liu, Boer Polymers Thin films interfaces branched polymer immobile layer In thin melt films of polymer chains, chains near the substrate adsorb onto the solid and form an irreversibly adsorbed layer. Studies show that thermal annealing is able to facilities the adsorptions. To date, most studies have focused on linear- polystyrene. It should be noted that the properties of thin films of branched chains are different from the properties of films of their linear analogs. Thus, researchers are curious regarding the adsorption of branched chains at polymer/solid interfaces. In this work, thin films of well-defined 5k and 15k star-shaped polystyrene (SPS) were thermally annealed at a temperature 60 °C above the polymer’s glass transition temperature. X-ray reflectivity results reveal the thickness of the irreversibly adsorbed layer remaining after a film cooled to room temperature is immersed multiple times in toluene. For 15k SPS (Rg ~ 2.1 nm) that layer thickness is rapidly established as 1.5 nm (0.7 Rg) and remains at that value with annealing. For 5k SPS (Rg ~ 1.2 nm), however, the thickness increases to 2 Rg after five days of annealing. Further study reveals also the chain architecture effects on the formation kinetics of the adsorbed layer. The time required for the adsorbed layer thickness to reach steady state for 5k SPS is more than one order of magnitude larger than that for 5k LPS. This difference is attributed to a greater cooperativity required for rearrangement in the layer of star chains, even though the molecules are formally unentangled. Moreover, the thickness of the steady state adsorbed layer relative to the radius of gyration for the star polymer is 1.5 times higher than for the linear polymer. 2018-06-08 English text University of Akron / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=akron1525261861391343 http://rave.ohiolink.edu/etdc/view?acc_num=akron1525261861391343 unrestricted This thesis or dissertation is protected by copyright: some rights reserved. It is licensed for use under a Creative Commons license. Specific terms and permissions are available from this document's record in the OhioLINK ETD Center.
collection NDLTD
language English
sources NDLTD
topic Polymers
Thin films
interfaces
branched polymer
immobile layer
spellingShingle Polymers
Thin films
interfaces
branched polymer
immobile layer
Liu, Boer
THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER
author Liu, Boer
author_facet Liu, Boer
author_sort Liu, Boer
title THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER
title_short THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER
title_full THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER
title_fullStr THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER
title_full_unstemmed THERMAL ANNEALING EFFECT ON UNENTANGLED STAR-SHAPED POLYSTYRENE RESIDUAL LAYER
title_sort thermal annealing effect on unentangled star-shaped polystyrene residual layer
publisher University of Akron / OhioLINK
publishDate 2018
url http://rave.ohiolink.edu/etdc/view?acc_num=akron1525261861391343
work_keys_str_mv AT liuboer thermalannealingeffectonunentangledstarshapedpolystyreneresiduallayer
_version_ 1719453824444268544

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