چكيده لاتين :
VinYIPyrrolidone-VinYI acetate (VP-VA) hydrophobically associating water-soluble copolymers were synthesized by free radical copolymerization. The effects of hydrophobic content and temperature on the viscosity and refractive index behaviour were investigated in detail. The critical concentration C* of the hydrophobically associating water-soluble copolymers was studied in the static state and in flowing solution by refractometry and viscosimetry, respectively. A dramatic decrease in solution viscosity of P(VP-VA) copolymers is observed with increasing the VA content at all temperatures. Also as the VA content in the copolymer increased, the solution refractive index of the copolymer decreased. The lowering in viscosity and refractive index reflects the contraction of the polymer coil because of intramolecular hydrophobic interactions. Variation of the dynamic and static critical concentration as a function of the temperature for P(VP-VA) copolymer in water has been investigated. The critical concentrations are lower when determined by refractive index measurements in the static state compared to the critical concentrations determined in the dynamic state using viscometer.
