SANS and NMR study on nanostructure of thermoresponsive double network hydrogels

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

SANS and NMR study on nanostructure of thermoresponsive double network hydrogels

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

SANS and NMR study on nanostructure of thermoresponsive double network hydrogels

Popis výsledku anglicky

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.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

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

Projekt

—

Návaznosti

O - Projekt operacniho programu

Rok uplatnění

2020

Kód důvěrnosti údajů

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

Název periodika

European Polymer Journal

ISSN

0014-3057

e-ISSN

—

Svazek periodika

137

Číslo periodika v rámci svazku

August 2020

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

9

Strana od-do

109929

Kód UT WoS článku

000567604100009

EID výsledku v databázi Scopus

2-s2.0-85089336737