Dilute Solution Properties of Tactic Poly(2-Hydroxyethyl Methacrylate)
Isotactic and syndiotactic poly(2-hydroxyethyl methacrylate) (PHEMA) have been prepared. Intrinsic viscosity-molecular weight relationships were established for the isotactic and syndiotactic PHEMA in N,N-dimethylformamide (DMF) at 25$^\circ$C by solution viscometry and light scattering. The unperturbed dimensions and interaction parameters have been examined in DMF, water, methanol, ethanol, and water-methanol (1:7 by volume) mixture for isotactic PHEMA and DMF, methanol, and water-methanol (1:7 by volume) mixture for syndiotactic PHEMA using the Stockmayer-Fixman representation. The results suggest that the compact random coil structure for isotactic PHEMA occurs in water solvent and isotactic PHEMA is more highly extended in polar solvents.
Effect of Ureas on the Viscometric Behavior of Water Soluble Isotactic Poly(2-Hydroxyethyl Methacrylate)
Isotactic poly(2-hydroxyethyl methacrylate) (PHEMA) is soluble and has the compact random coil structure in water solvent. The effect of six ureas (thiourea, urea, methylurea, ethylurea, 1.3-dimethylurea, and tetramethylurea) on the viscometric behavior of aqueous solutions of isotactic PHEMA as a function of urea concentrations at 25$^\circ$C has been investigated. The compact random coil structure is found to disappear as ureas are added. The result is discussed in terms of water structure-breaking and -making of solutes, and hydrophobic interactions between hydrophobic groups. In addition, experiments were performed with aqueous isotactic PHEMA solution at four different temperatures. The temperature-dependant conformational behavior of isotactic PHEMA in pure water presents that the most compact conformation is occured at 20$^\circ$C among four different temperatures.