TY  - JOUR
AU  - Cors, Marian
AU  - Wiehemeier, Lars
AU  - Wrede, Oliver
AU  - Feoktystov, Artem
AU  - Cousin, Fabrice
AU  - Hellweg, Thomas
AU  - Oberdisse, Julian
TI  - Contrast variation SANS measurement of shell monomer density profiles of smart core–shell microgels
JO  - Soft matter
VL  - 16
IS  - 7
SN  - 1744-6848
CY  - London
PB  - Royal Soc. of Chemistry
M1  - FZJ-2020-00692
SP  - 1922-1930
PY  - 2020
AB  - The radial density profile of deuterated poly(N,n-propyl acrylamide) shell monomers within core–shell microgels has been studied by small-angle neutron scattering in order to shed light on the origin of their linear thermally-induced swelling. The poly(N-isopropyl methacrylamide) core monomers have been contrast-matched by the H2O/D2O solvent mixture, and the intensity thus provides a direct measurement of the spatial distribution of the shell monomers. Straightforward modelling shows that their structure does not correspond to the expected picture of a well-defined external shell. A multi-shell model solved by a reverse Monte Carlo approach is then applied to extract the monomer density as a function of temperature and of the core crosslinking. It is found that most shell monomers fill the core at high temperatures approaching synthesis conditions of collapsed particles, forming only a dilute corona. As the core monomers tend to swell at lower temperatures, a skeleton of insoluble shell monomers hinders swelling, inducing the progressive linear thermoresponse.
LB  - PUB:(DE-HGF)16
C6  - pmid:31995091
UR  - <Go to ISI:>//WOS:000527137300020
DO  - DOI:10.1039/C9SM02036E
UR  - https://juser.fz-juelich.de/record/873380
ER  -