Gelling Behavior of PVA or its Blends with Other Polymers in Presence of Borax and Thermochromism in Such Gel Network Materials

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Authors

  • Department of Chemistry, Manipur University, Canchipur, Imphal 795 003 ,IN
  • Department of Chemistry, Manipur University, Canchipur, Imphal 795 003 ,IN

DOI:

https://doi.org/10.18311/jsst/2011/1868

Keywords:

PVA/Borax Hydrogels, Didiol Cross-Links, Thermochromism, Polymer Blends, Network Materials.

Abstract

Gelling behavior of PVA or its blends with other polymers such as polyvinyl pyrrolidone (PVP), polyethylene oxide (PEO), hydroxyl propyl cellulose (HPC), agar and gelatin A has been studied as a function of borax concentration from viscosity measurements. The pH of the borax cross linked hydrogels of PVA or its blends showed an interesting behavior with temperature - it initially increases with temperature up to a maximum and then decreases with further increase in the temperature. Such temperature sensitive transparent hydrogels when embedded with a suitable acid-base indicator like phenolphthalein showed reversible thermochromism. However, thermochromism was not observed in the hydrogels of polymer blends if the amount of PVA in the blend was less than 60%. The results suggest that thermochromism in dye embedded borax cross-linked hydrogels is due to the formation of didiol cross-links between hydroxyl groups in PVA and the borax, which is governed by change in temperature. The effect of the addition of an anionic (SDS), or a non ionic (TX-100) surfactant on the thermochromic behavior of the hydrogels has also been studied.