Počet záznamů: 1  

Poly(N-isopropylacrylamide)-SiO2 nanocomposites interpenetrated by starch: Stimuli-responsive hydrogels with attractive tensile properties

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    0471497 - ÚMCH 2017 RIV GB eng J - Článek v odborném periodiku
    Depa, Katarzyna - Strachota, Adam - Šlouf, Miroslav - Brus, Jiří
    Poly(N-isopropylacrylamide)-SiO2 nanocomposites interpenetrated by starch: Stimuli-responsive hydrogels with attractive tensile properties.
    European Polymer Journal. Roč. 88, March (2017), s. 349-372. ISSN 0014-3057. E-ISSN 1873-1945
    Grant CEP: GA MŠMT(CZ) LD14010
    Grant ostatní: European Commission(XE) COST Action MP1202 HINT
    Institucionální podpora: RVO:61389013
    Klíčová slova: PNIPAm hydrogel * starch * silica
    Obor OECD: Polymer science
    Impakt faktor: 3.741, rok: 2017

    Doubly filled nanocomposite poly(N-isopropylacrylamide)-SiO2-starch hydrogels were prepared via simultaneous polymerization of N-isopropylacrylamide (NIPAm) and tetramethoxysilane hydrolysis, in the presence of colloid amylopectin starch (4–30 wt.% in dry gel). Besides bulk hydrogels, also highly porous ones were prepared, the latter via solvent freezing during synthesis (cryogels). The branched starch molecules, which interpenetrate PNIPAm, appear to enforce less crosslinked but more regular PNIPAm network with a wider mesh, in place of the irregular one, which is normally obtained in divinyl-crosslinked PNIPAm. The hydroxyl groups of starch form efficient hydrogen bonds to the PNIPAm matrix, as well as to the SiO2 nanofiller, which in turn also has strong H-bonds to PNIPAm. In bulk gels, a strong synergy of both fillers is clearly observed, leading to a marked increase in moduli, in spite of the wider network mesh. Very distinct is the improvement of tensile properties if starch is incorporated: the elongation at break increases 2 times in porous gels and 3–6 times in bulk ones. The gels’ toughness is also tremendously improved. The porous PNIPAm-SiO2-starch gels further display an ultra-fast swelling response to temperature jumps, both deswelling and re-swelling. Interestingly, starch-rich bulk PNIPAm-starch and PNIPAm-SiO2-starch gels also display a very fast (and also very extensive) temperature-induced deswelling, while their re-swelling is very slow (as would be expected). This behaviour practically represents a strong ‘one way response’ to temperature jumps. The specific properties of the interface between swollen PNIPAm and starch enable the rapid water escape from the bulk gels, especially if starch-rich domains are present.
    Trvalý link: http://hdl.handle.net/11104/0268899

     
     
Počet záznamů: 1  

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