ISSN:
0887-624X
Keywords:
thermosetting cyanate networks
;
foams
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
A general means of generating nanofoams from thermosetting materials was investigated. Foams were prepared from a thermosetting monomer copolymerized with a thermally labile material, such that the thermally labile coblock is the dispersed phase. Upon thermal treatment, the thermally unstable block undergoes thermolysis, leaving pores where the size and shape are dictated by the initial morphology. For this investigation the thermosetting resin was prepared from a cyanate monomer (4,4′-(hexafluoroisopropylidene) diphenyl-cyanate), with either poly(propylene oxide) or a propylene oxide-urethane copolymer as the thermally labile block. The propylene oxide-based oligomers were molecularly miscible with the cyanate resin over the entire range of compositions, and molecular weights investigated, but developed a two-phase structure upon reaction to form the polycyanurate thermoset. The molecular weight and composition of propylene oxide chemically incorporated into the polycyanurate was varied along with the curing condition, solvents, and catalyst. Dynamic mechanical and small-angle x-ray scattering measurements demonstrated a two-phase morphology in the cured networks wherein the propylene oxide domains are dispersed in the polycyanurate matrix. Upon decomposition of the propylene oxide component, however, the foam was found to collapse. Samples with the larger void size retained, to a large extent, their void composition upon the thermolysis of the propylene oxide component. © 1996 John Wiley & Sons, Inc.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
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