Study On The Properties And Prediction Of Poly Acetal Derivatives As Gelator

Three poly sorbitol acetal derivatives 2,4-(3,4-dichlorobenzylidene)-D-sorbitol(gelator A),1,3:2,4-di(3,4-dichlorobenzylidene)-D-sorbitol(gelator B)and 1,3:2,5:4,6-tris(3,4-dichlorobenzylidene)-D-mannitol(gelator C)with different hydrogen bonding sites and ?-? stacking interaction were synthesized.Based on Hansen solubility parameters(HSPs),35 pure solvents were selected.Gelation behaviours of three compounds were investigated at 2%(w/v)and saturated concentration.The results showed that solutions/sols were likely to assemble into gels or precipitates by increasing the concentrations of gelators.Rheological measurements and SEM figures were utilized to prove that gels formed at relatively high concentrations(>5%,w/v)were true gels.Gelation behaviours of those samples were correlated with solubility parameters(including HSPs,Teas parameters,Flory-Huggins interaction parameter),but with no success.Samples were insoluble at normal atmosphere may dissolve and form gels at higher pressure.Based on the gelation behaviours of gelators in pure solvents at saturated concentrations,binary solvent mixtures were selected by using 2-D Teas plot.The gelation behaviours of gelator A,B and C in selected binary solvent mixtures were investigated.The results demonstrated that whether to form a gel or not depends on the gelation behaviours in pure solvents at saturated concentrations.If the gelator can form a gel in one component of the solvent mixtures,it may form a gel in solvent mixture at a certain volume ratio;if it cannot form a gel in any component,it cannot form a gel in solvent mixtures.FTIR and XRD were utilized to prove that poor solvent didn't change the self-assembly patterns of the gelator,but reducing the critical gelation concentration(CGC).Correlating the gelation behaviours with Flory-Huggins and found that Flory-Huggins parameter can only be useful within a specific range.