Synthesis And Gelation Properties Of Room Temperature Phase-selective Organogelators

Phase-selective gelators have attracted widespread attention from scientists due to their potential application in oil spill recovery.In this paper,a series of hydroxy-protected acetal-substituted D-glucose amide derivatives(PGn,B12 and C12)and a series of oleylamine-based gelators(A18,B18 and C18)were designed and synthesized.The relationship between the gelator structures and the gelation properties were studied respectively.The self-assembly mechanism of gels and the room temperature gelation mechanism were also explored.The application of the gelators in oil spill treatment was also tested.For the gelators PGn(n=4,8,10,12,14,16),B12 and C12,it was found that the length of the alkyl chain of the gelators has a significant effect on the gelation properties.In addition,the structure of the protecting groups also has a significant effect on the gelation properties.Self-assembly mechanism of PG12 gels was proposed by POM,SEM,FT-IR,~1H NMR,XRD coupled with theoretical calculation.It was found that gelator PG12 has phase-selective gelation for a variety of oils with ethanol as a co-solvent,which showed potential application value in oil spill recovery.Gelator A18,B18,C18 and G18 have similar gelation properties in hydrocarbon solvents through heating and cooling process.Surprisingly,the oleylamine-based gelators have rapid room temperature gelation properties in hydrocarbon solvents,while G18 fail to gel these solvents at room temperature.These outcomes indicated that fine-tuning of the alkyl chain of through introduction of cis C=C significantly enhanced room temperature gelation abilities in hydrocarbon solvents.Among these,A18exhibited rapid room temperature phase-selective gelation abilities in both aromatics and crude oils.The discovery of PSOGs with fast gelation abilities and high recovery rates in hydrocarbon solvents,undoubtedly promote the development of powder form PSOGs for emergency treatments of aromatics leakage and oil spills.Compared to G18,the presence of the middle cis double bond in the alkyl chain of B18(or A18)weakened the van der Waals forces leading to the poor crystallinity as observed in XRD patterns.So,the less crystalline stacking of alkyl chains resulted in the room temperature gelation properties of the oleylamine-based gelators in hydrocarbon solvents.