Poly(vinyl alcohol)/sulfonated polyester hydrogels produced by freezing and thawing technique: preparation and characterization

Materials Research

Caio Marcio Paranhos²  Renata Nunes Oliveira²  Bluma Guenther Soares²  Luiz Antônio Pessan¹ 

[1] ,Universidade Federal do Rio de Janeiro Centro de Tecnologia Instituto de MacromoléculasRio de Janeiro RJ ,Brazil

关键词: hydrogels;    freezing-thawing process;    poly(vinyl alcohol);   

DOI  :  10.1590/S1516-14392007000100010

来源: SciELO

【 摘 要 】

Poly(vinyl alcohol) (PVA) hydrogels were obtained by freezing (-22 °C) and thawing (+25 °C) process, resulting in a semi-interpenetrating polymer network (s-IPN) with a sulfonated polyester (PES). The cryo-gels samples were analysed in terms of its water uptake capacity (WU) as a function of pH, temperature and ionic strength. WU of all samples were relatively high, and they showed a reasonable sensitivity to both pH and ionic strength. The pH- and ionic strength dependence is attributed to the dissociation of ionizable groups of PES. The degrees of crystallinity of the cryo-gels, determined by using differential scanning calorimetry (DSC), are lower than pure PVA. Besides, decrease of glass transition temperature (Tg) of the samples when compared with pure PVA was observed. This results are due interactions between PVA and PES, which lead to an increase on the amorphous content of the hydrogels. Our results show that, despite of changes in the microstructure of the hydrogels due the presence of the polyelectrolyte, the cryo-gels reveal a long-term stability.

【 授权许可】

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