Phenomena affecting morphology of microporous poly(acrylonitrile) prepared via phase separation from solution

Conference · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6260599

Legasse, R R; Weagley, R J; Leslie, P K; Schneider, D A

This paper is concerned with controlling the morphology of microporous polymers prepared via thermal demixing of solutions. 2 wt % solutions of poly(acrylonitrile) in maleic anhydride, a poor solvent, are first cooled to produce separated polymer-rich and solvent-rich phases. Removing the solvent by freeze drying then produces a microporous material having a density of 33 mg/cm{sup 3}, a void fraction of 97%, and a pore size of about 10 {mu}m. We find that the morphology cannot be explained by existing models, which focus on phase diagrams and kinetics of phase transformations during cooling of the solution. In conflict with those models, we find that two radically different morphologies can be produced even when the polymer concentration and cooling path are held strictly constant. A hypothesis that polymer degradation causes the different morphologies is not supported by GPC, {sup 13}C NMR, and FTIR experiments. Instead, we offer evidence that the different microporous morphologies are caused by different polymer conformations in solutions having the same concentration and temperature. 11 refs., 3 figs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• Sponsoring Organization: DOE/DP
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6260599
• Report Number(s): SAND-90-2929C; CONF-910402--1; ON: DE91004501
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
360602 -- Other Materials-- Structure & Phase Studies
ACRYLONITRILE
ANHYDRIDES
CARBON 13
CARBON ISOTOPES
CHEMICAL PREPARATION
CRYSTAL STRUCTURE
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MICROSTRUCTURE
MORPHOLOGY
NITRILES
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC POLYMERS
PHASE TRANSFORMATIONS
POLYMERS
POROSITY
RESONANCE
STABLE ISOTOPES
SYNTHESIS