热缔合接枝物HPAM-g-PNIPAm的温敏增稠性能

Thermothickening Properties of Graft Copolymer HPAM-g-PNIPAm

采用流变仪与毛细管粘度计研究了热缔合接枝聚合物———水解聚丙烯酰胺-g-聚(N-异丙基丙烯酰胺)(HPAM-g-PNIPAm)盐水溶液流变特性,测定了外加盐浓度、聚合物浓度、剪切速率及接枝率和接枝链长对HPAM-g-PNIPAm温敏增稠效果的影响。结果表明,此接枝聚合物在接枝率大于4%,接枝侧链相对分子质量大于8000且聚合物质量浓度大于2g/L时具有较强的温敏增稠性,即在30～50℃水溶液中,粘度随温度的升高而增大,且增稠效果随外加盐浓度的升高而加大。

Novel thermosensitive amphiphilic graft polymers--hydrolyzed polyacrylamide-graft- poly(N-isopropylacrylamide) (HPAM-g-PNIPAm) were synthesized by macromonomer technology. The viscosity properties of these graft copolymers aqueous solution were determined. These graft copolymers had thermothickening characteristic,i.e. viscosity of HPAM-g-PNIPAm aqueous solution increased with increasing temperature when above the cloud point of PNIPAm side chain. Cloud points of the graft copolymers were about 33 ℃ as determined by turbidity changing,basically independent with the content and length of PNIPAm side chain. Influence of various conditions(copolymer concentration,shear rate,added salt concentration) and structure characteristics (PNIPAm side chain length,PNIPAm side chain content) on thermothickening behavior were examined and interpreted in the light of the concept of thermally induced hydrophobic association and theory of polymer solution. HPAM-g-PNIPAm has good thermothickening properties.