The use of styrenic copolymers to generate polyimide nanofoams

New routes for the synthesis of high T sub(g) thermally stable polymer foams with pore sizes in the nanometre regime have been developed. Foams were prepared by casting well-defined microphase-separated block copolymers comprising a thermally stable block and a thermally labile material. At properly...

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Bibliographic Details
Published in:Polymer (Guilford) 1995, Vol.36 (25), p.4855-4866
Main Authors: HEDRICK, J. L, HAWKER, C. J, DIPIETRO, R, JEROME, R, CHARLIER, Y
Format: Article
Language:English
Subjects:
Applied sciences
Block copolymers
Cellular
Decomposition
Exact sciences and technology
Forms of application and semi-finished materials
Heat treatment
Heating
Monomers
Morphology
Plastics casting
Polyimides
Polymer industry, paints, wood
Polystyrenes
Synthesis (chemical)
Technology of polymers
Thermogravimetric analysis
Volume fraction
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Summary:New routes for the synthesis of high T sub(g) thermally stable polymer foams with pore sizes in the nanometre regime have been developed. Foams were prepared by casting well-defined microphase-separated block copolymers comprising a thermally stable block and a thermally labile material. At properly designed volume fractions, the morphology provides a matrix of the thermally stable material with the thermally labile material as the dispersed phase. Upon thermal treatment, the thermally unstable block undergoes thermolysis generating pores, the size and shape of which are dictated by the initial copolymer morphology. Several labile blocks were surveyed including polystyrene, poly( alpha -methylstyrene) and several alpha -methylstyrene/styrene copolymers. Each of these polymers can unzip to its monomer upon heating; however, the rate is substantially slower for polystyrene. The copolymers were synthesized through either the poly(amic acid) precursor, followed by chemical imidization to the polyimide form, or the poly(amic alkyl ester) precursor followed by thermal imidization. The decomposition of the labile coblock was studied by thermogravimetric and dynamic mechanical analysis. Upon decomposition, the foams showed pore sizes in the nanometre regime along with the expected reduction in mass density.
ISSN:0032-3861
1873-2291
DOI:10.1016/00323-8619(59)9303C-