Die Makromolekulare Chemie · 1984 · 16 citations · 11 references
Natural SciencesChemistryMaterials SciencePolymer ChemistryPolymer EngineeringPolymer MaterialsGelsHydrogelsPolymer CharacterizationPolymer Physical ChemistryPolymer PhysicsPolymer StructureBiopolymer GelsChemical CrosslinkingChemical GelsCrosslinked PolymersGel Network FormationGelation MechanismsGelation TemperaturePolymer Gelation
Abstract Aqueous solutions of poly( N ‐vinyl‐2‐pyrrolidone) are converted to gels by reaction with potassium peroxydisulfate K 2 S 2 O 8 . The degree of crosslinking in the gel fractions depends on the amount of persulfate used. The degree of crosslinking is related to the amount of non‐freezing bound water in the gels by means of differential scanning calorimetry in the temperature range from −50°C to + 170°C. The chemical nature of the bonds formed during gelation is studied by 1 H and 13 C NMR Spectroscopy and by swelling tests. NMR measurements point to the formation of aliphatic sidechains as well as crosslinks in the gelation. The swelling tests give low values for the number of crosslinks, hence the formation of branched chains strongly influences the properties of the gels. In contrast to what was expected no carboxyl groups are found in the gels.
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