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Porous hybrid poly(N-isopropylacrylamide) hydrogels with very fast volume response to temperature and pH
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SYSNO ASEP 0508103 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Porous hybrid poly(N-isopropylacrylamide) hydrogels with very fast volume response to temperature and pH Author(s) Strachota, Beata (UMCH-V) RID
Oleksyuk, Khrystyna (UMCH-V)
Strachota, Adam (UMCH-V) RID, ORCID
Šlouf, Miroslav (UMCH-V) RID, ORCIDArticle number 109213 Source Title European Polymer Journal. - : Elsevier - ISSN 0014-3057
Roč. 120, November (2019), s. 1-14Number of pages 14 s. Language eng - English Country GB - United Kingdom Keywords polymeric hydrogels ; smart materials ; nanocomposites Subject RIV CD - Macromolecular Chemistry OECD category Polymer science R&D Projects GA19-04925S GA ČR - Czech Science Foundation (CSF) Method of publishing Limited access Institutional support UMCH-V - RVO:61389013 UT WOS 000498309000005 EID SCOPUS 85071879458 DOI 10.1016/j.eurpolymj.2019.109213 Annotation Super-porous hydrogels were prepared, which are able of fast to ultra-fast volume response to temperature and to pH, and thus show a promise as soft actuators. The hydrogels are based on the poly(N-isopropylacrylamide) (PNIPAm)/silica nanocomposite, in which the filler strongly raises the modulus and also stabilizes the pore walls against collapse during deswelling. The well-interconnected sub-millimetre-sized porosity was generated via solvent freezing during synthesis. The gels morphology makes possible both ultra-fast deswelling and re-swelling (5.5 s for 70% in both directions, in response to T). This work focused on introducing pH-responsiveness into the gels. To this end, 1–10 mol% of sodium methacrylate (SMA) were incorporated as co-monomer. Distinct pH-responsiveness was achieved already at 1 mol% of SMA. Increase of SMA content markedly expands the temperature range of the pH-responsiveness and raises its amplitude. At the same time the increase of SMA content reduces the amplitude of the T-responsiveness, which is only moderate at 10 mol% SMA. The rate of pH-response was found to be always slower than in case of the T-response: 75 s are needed for 70% of de-swelling, and 90 min for 70% of re-swelling. The vast difference in the rates of pH- and T- response can be explained by different mechanisms of stimulus propagation (momentum transfer for T, vs. diffusion for pH) and by the mechanical effect of a contracting stiff and porous surface layer (much faster pH-deswelling than re-swelling). More generally, in case of the pH-stimulus, the mechanistic limits of its propagation in ‘simple’ porous gels become evident. Workplace Institute of Macromolecular Chemistry Contact Eva Čechová, cechova@imc.cas.cz ; Tel.: 296 809 358 Year of Publishing 2020 Electronic address https://www.sciencedirect.com/science/article/pii/S0014305719313965?via%3Dihub
Number of the records: 1