Highly branched poly(N-isopropyl acrylamide) (HB-PNIPAM) and poly(N-isopropyl acrylamide-graft-N-vinyl pyrollidinone) (poly(NIPAM-g-NVP) formed colloidal particles above the lower critical solution temperature due to a coil-to-globule transition. At moderate concentrations these colloidal particles aggregated to form gels. The gels were stabilized by repulsive interactions between the polymer end groups of the highly branched polymer or the highly solvated polyNVP grafts in poly(NIPAM-g-NVP). HB-PNIPAM was prepared with both carboxylic acid and oligo-arginine end groups and both the rheology and the internal structure were studied. Similarly, the rheological response of the poly(NIPAM-g-NVP) was studied and clear gel-points were observed. Also, it was possible to add collagen to the poly(NIPAM-g-NVP) to create synthetic-natural hybrid gels that were significantly tougher than the non-modified poly(NIPAM-g-NVP) gels. All of the gels supported 3D cell culture and the cells could be released by simple cooling, which redissolved the polymer as it progressed into the coil confirmation.

Colloidal gels formed from branched poly(N-isopropyl acrlyamide)

244th National Meeting (2012)

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