THE FORMATION OF HIGHER-ORDER STRUCTURES OF 1,3 IS-O-INSIDE-BIS-O-(P-METHYLBENZYLIDENE)-D-SORBITOL IN PHYSICAL GELS OF MOLTEN POLYMERS AND ORGANIC-SOLVENTS/
T. Kobayashi et al., THE FORMATION OF HIGHER-ORDER STRUCTURES OF 1,3 IS-O-INSIDE-BIS-O-(P-METHYLBENZYLIDENE)-D-SORBITOL IN PHYSICAL GELS OF MOLTEN POLYMERS AND ORGANIC-SOLVENTS/, Kobunshi ronbunshu, 55(10), 1998, pp. 613-627
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 sol
vents and molten polymers. Falling ball, dynamic viscoelasticity (DVE)
, and small-angle X-ray scattering (SAXS) methods are useful for deter
ming sol-gel phase transition temperatures (T-fg's) of these physical
gels, The X-ray analysis and the theoretical computer calculation appl
ying the MOPAC system explored one of the possible models of the fine
structure for PDTS fibril crystal networks; unit cell for the PDTS cry
stal 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 o
f pair of intermolecular hydrogen bonded PDTS molecules with dipole mo
ments antiparallel each other along the c-axis. The self-assembly form
ation of specific fibril crystals accompanied with sol-gel phase trans
ition is based upon the relatively faster crystal growth along the c-a
xis than perpendicular controlled by thermodynamical stability of poly
meric interhydrogen bonding among PDTS molecules. According to the DVE
analysis at a critical gel for the 2.5% PDTS/PS system, PDTS gel netw
orks 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 s
cattering 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.