Epoxy Networks Modified by a New Class of Oligomeric Silsesquioxanes Bearing Multiple Intramolecular Rings Formed Through Si-O-C Bonds

IGNACIO E. DELL'ERBA, DIANA P. FASCE, ROBERTO J. J. WILLIAMS, ROSA ERRA-BALSELLS,YUKO FUKUYAMA, HIROSHI NONAMI

MACROMOLECULAR MATERIALS AND ENGINEERING (PRINT)

Wiley-VCH

Lugar: Weinheim; Año: 2004 vol. 289 p. 315 - 323

1438-7492

A new class of silsesquioxane (SSO), containing species with 2 to 9 Si atoms bearing multiple intramolecular rings formed through Si-O-C bonds, was synthesized as a glassy powder. It was characterized by UV-MALDI-TOF MS, 29Si NMR and FTIR. Solutions containing different amounts of SSO in diglycydylether of bisphenol A (DGEBA), were homopolymerized in the presence of (4-dimethylamino)pyridine (DMAP) as initiator, leading to SSO-modified epoxy networks. SSO species were covalently bonded to the epoxy network without any evidence of phase separation. The SSO addition provoked an increase in the elastic modulus in the glassy state and a decrease in the glass transition temperature (antiplasticization). An increase in the intensity of tanä was also observed, that was associated to the flexibility of SSO structures. DMAP was much more effective than other usual initiators (like benzyldimethylamine, BDMA), to promote the generation of long primary chains in the epoxy homopolymerization. This resulted in a range of high values both for glass transition temperatures and elastic moduli in the rubbery state.