SANS and NMR study on nanostructure of thermoresponsive double network hydrogels

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F20%3A10419404" target="_blank" >RIV/00216208:11320/20:10419404 - isvavai.cz</a>

Result on the web

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=u16OqkoXg9" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=u16OqkoXg9</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.eurpolymj.2020.109929" target="_blank" >10.1016/j.eurpolymj.2020.109929</a>

Result language

angličtina

Original language name

SANS and NMR study on nanostructure of thermoresponsive double network hydrogels

Original language description

Temperature induced changes of nanostructure of double network (DN) hydrogels were investigated by a combination of small-angle neutron (SANS) and H-1 nuclear magnetic resonance (NMR) spectroscopy. The DN hydrogels consist of the first densely crosslinked thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) network swollen in water in which a second loosely crosslinked hydrophilic polyacrylamide (PAAm) network was prepared. In the series, the crosslinking density of the first network is varied while the crosslinking density of the second network is kept constant. At high-q range (q being the magnitude of scattering vector), SANS profiles are governed by a term originating from thermal movement of polymer segments in water. For q &gt; 0.1 angstrom(-1), this term scales as q(-alpha) and the scaling exponent a obtains values lower than 5/3 (at T = 25 degrees C) to ca 2 (at T &gt;= 35 degrees C) in agreement to the change of quality of PNIPAAm-water interaction. At low-q range, an excess scattering due to formation of large loose domains with non-uniform concentration of crosslinks is observed. At temperatures below the deswelling temperature, T-dsw, the excess scattering is relatively week since the domains differ little in the neutron scattering length density. However, NMR results show that mobility of a great part of NIPAAm units in DN hydrogels is significantly reduced even below T-dsw. At temperatures above T(dsw )the excess scattering becomes much stronger showing q(-4) scaling in Porod&apos;s region corresponding to formation of water-poor and water-rich domains separated by well-defined interface. The size of domains grows with increasing temperature and decreasing crosslinking density of the first network. The SANS intensities from DN hydrogels are reduced with respect to SN hydrogels which is attributed to lower scattering contrast due to an increased water content in water-poor phase caused by the presence of the second hydrophilic PAAm network.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10301 - Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect)

Project

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Continuities

O - Projekt operacniho programu

Publication year

2020

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

European Polymer Journal

ISSN

0014-3057

e-ISSN

—

Volume of the periodical

137

Issue of the periodical within the volume

August 2020

Country of publishing house

GB - UNITED KINGDOM

Number of pages

9

Pages from-to

109929

UT code for WoS article

000567604100009

EID of the result in the Scopus database

2-s2.0-85089336737