Formation of junction zones in thermoreversible methylcellulose gels

To analyze the structure of junction zones formed in methylcellulose (MC) gel, the modified Eldridge-Ferry method was applied to phase diagrams for aqueous solutions of different molecular weight MCs derived from micro-DSC, small-angle X-ray scattering, and visual inspection. The results suggested that junctions in MC gels took thin, rodlike fringed-micellar crystallites. The junction multiplicity s decreased from 4.3 for low-temperature melting gels to 2.0 for high-temperature melting gels. With increasing molecular weight, the number zeta of statistical units in a junction along a single chain increased from 27 to 54. Because the number depends sensitively on the enthalpy of bonding per mole of the repeat units of MC, our estimate is considered to give an upper bound to the junction length. (C) 2001 John Wiley & Sons, Inc.