Hydrophobic association hydrogels（HA-gels） with high mechanical strength were prepared by free radical micellar copolymerization in aqueous solutions of acrylamide（AM）, anion surfactant sodium dodecyl sulfate（SDS） and a small amount of hydrophobic monomer octylphenol polyoxyethylene（7） acrylate（OP-7-AC）. We found that the molar ratio of SDS to OP-7-AC has a great effect on the tensile strength and other mechanical property parameters. The best ratio point R＇ was determined. On the basis of Mooney theory and statistical theory, the critical tensile ratios and critical tensile strengths of the hydrogels were obtained, elastic parameters C1 and C2 were calculated via uniaxial tensile equation and structural parameters, such as the effective network chain density and the averaged molecular weight of the chain between cross-linking points of all the hydrogels were evaluated. The results indicate that the variation of mechanical property parameters depends on the number of effective cross-linking points and the match degree of long and short chains.
LIANG Zi GAO Tingting XU Jianan LI Zhiying LIU Xiaoli LIU Fengqi
The effects of the concentration of sodium chloride in an aqueous solution（cNacl and the temperature on the molecular size of poly（sulfobetaine methacrylate）（PSBMA） were studied via viscometry and dynamic light scattering（DLS）. The morphology of single-chain PSBMA was determined by atomic force microscopy（AFM）. The results demonstrate that the hydrodynamic diameter of PSBMA can be expressed as a continuous function of CNaCl, with the molecular size of PSBMA increasing and eventually approaching an asymptotic value with increasing CNaCl. The molecular size of PSBMA at a lower CNaCI（0.04 mol/L） increases with increasing temperature, which is the opposite of the temperature effect at a higher CNaCl（2.0 mol/L）. Therefore, the internal structure of PSBMA chains in solutions with a low salt concentration differs from that in solutions with a high salt concentration. In addition, the morphology of single chains of PSBMA appears to be spherical, containing 89% void space, and the apparent size of the dried chains is almost identical to that in solution.
