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Gels obtained by reacting diglycidyl eter terminated poly(dimethylsiloxane) with various diamines

Poly(dimethtlsiloxane), PDMS is the most common of semi-inorganic polysiloxane polymers. PDMS is a versatile material with many excellent chemical, physical, and electrical properties including tissue equivalent characteristics [1]. Curing of PDMS oligomers terminated with reactive groups with appropriate reactants may produce gels. Various primary diamines that react with epoxy group [2] at relatively low temperatures were used as curing agents for diglycidyl eter terminated poly(dimethtlsiloxane), PDMS-DGE. Transparent gels that differed in quality and firmness were obtained. The influence of diamine type and reaction conditions on gels was studied by vibration spectroscopy, solvent extraction and thermal analysis. Diamine type was a primary factor defining properties of a gel. The gel prepared with ethylenediamine, EDA, had largest mass loss on extraction in hexane. The loss of mass decreased in order ethylenediamine, triethylenetetramine, diethylenetriamine while the gel prepared with 1, 3-diamino-2-propanol, DAP, was the most stable. The gel prepared with EDA was the softest and that with DAP was the firmest. At 50 ºC curing reaction was faster and its extent greater than at room temperature so the gels had somewhat better properties than those obtained at room temperature. Vibration spectroscopy confirmed that differences in properties of gels depended on curing agent used [3] and indicate the role of additional hydroxy group of DAP in stabilizing the gel by hydrogen bonding. References [1] J. E. Mark, Some interesting things about polysiloxanes, Accounts of Chemical Research, 37 (2004), 946-953. [2] O. Hara, Curing agents for epoxy resin, Three Bond Technical News, 32 (1990), 1-10. [3] González, J. C. Cabanelas, J. Baselga, Applications of FTIR on epoxy resins - identification, monitoring the curing process, phase separation and water uptake, ur T. Theophile, Infrared Spectroscopy - Materials Science, Engineering and Technology, InTech, 2012, 261-284.

polysiloxane ; diamine ; transparent gel ; vibration spectroscopies ; DSC

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