关键词：
1,3 : 2,4-cis-inside-bis-O-(p-methyl benzylidene)-D-sorbitol
sol-gel phase transition
fine crystal structure
mass fractal
bicontinuous percolation networks
polymeric interhydrogen bond
self-assembly formation
摘要：
It was found that 1,3 :2,4-cis-O- inside-bis-O- (p-methyl benzylidene) -D-sorbitol (PDTS) is a gelling agent for a wide range of organic solvents and molten polymers. Falling ball, dynamic viscoelasticity (DVE), and small-angle X-ray scattering (SAXS) methods are useful for determing sol-gel phase transition temperatures (T-fg's) of these physical gels, The X-ray analysis and the theoretical computer calculation applying the MOPAC system explored one of the possible models of the fine structure for PDTS fibril crystal networks;unit cell for the PDTS crystal is a hexagonal lattice, a = b=31.5 Angstrom, c=4.4 Angstrom, and gamma=120 degrees, and each lattice point is occupied with four sets of pair of intermolecular hydrogen bonded PDTS molecules with dipole moments antiparallel each other along the c-axis. The self-assembly formation of specific fibril crystals accompanied with sol-gel phase transition is based upon the relatively faster crystal growth along the c-axis than perpendicular controlled by thermodynamical stability of polymeric interhydrogen bonding among PDTS molecules. According to the DVE analysis at a critical gel for the 2.5% PDTS/PS system, PDTS gel networks in mesoscopic range are characterized that they are mass fractal with d(f)= 2.4, in accordance with d(f)=2.3 +/-0.2 obtained from its scattering profiles. The strengths of percolation networks made of 1.0, 1.25, and 2.5 wt% of PDTS are about 3.5 X 10(4), 4.3 X 10(5), and 1.0 X 10(6) Pa, respectively.
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