Organo-gelation using Microwave Heating Source: The Case of a Polyurethane Model Compound

Organo-gels with a series of biscarbamates as gelators were prepared using microwave (MW) heating source as well as conventional heating. Biscarbamates with alkyl side chain lengths varying from C5 to C18 were used, with six solvents having dipole moments ranging from 0.07 to 4.3 D. The minimum gelation concentration and the time required for dissolution were significantly reduced with MW heating with benzonitrile, compared to the conventional heating for all the side chain lengths of the biscarbamates. While such reduction was pronounced with benzonitrile and dimethyl sulfoxide with large dipole moments, the time required for dissolution increased with MW heating (compared to the conventional) in the case of xylene and toluene with small dipole moments. Thus, MW is effective with solvents possessing large dipole moments. Although the gels consist of fibers using both methods, an inherent orientation of these fibers was seen with MW heating. *Corresponding author: Sundararajan PR, Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1S 5B6, Canada, Tel: 6135202600; Ext 3635; E-mail: [email protected] Received February 04, 2016; Accepted February 12, 2016; Published February 22, 2016 Citation: Chan ASW, Sundararajan PR (2016) Organo-gelation using Microwave Heating Source: The Case of a Polyurethane Model Compound. J Material Sci Eng 5: 233. doi:10.4172/2169-0022.1000233 Copyright: © 2016 Chan ASW, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. upon heating to a higher temperature. Cooling the solution leads to the self-assembly of the molecule in the presence of the solvent, with predominant growth along the hydrogen bonding direction [14]. Such directional growth results in fibers which trap the solvent molecules and gelation occur. A minimum concentration of the gelator is required for gelation. In addition, the phenomenon also depends on the solutesolvent pair. In the absence of gelation, crystallization and precipitation would occur. While several studies on MW assisted synthesis and processing have been reported in the literature as mentioned above, we examined the effect of MW heating method on organo-gelation using the biscarbamates, with alkyl chain length ranging from C5 to C18. Six solvents with different dipole moments were used. The minimum concentration (Cmin) of biscarbamate required for gelation, the dissolution and the gel-to-solution temperatures, as well as the morphology of the gels was determined using MW and conventional heating.