(708d) Microfluidic Studies of Nonsolvent-Induced Phase Inversion of Polymer Solutions

Membranes offer an environmentally benign approach to gas separations, mainly because of reduced process energy requirements. For industrial processes, asymmetric membranes with a thin selective layer on a porous support layer are normally prepared by phase inversion of a polymer solution. This process results in high selectivity, while maintaining a sufficiently high gas throughput. The kinetics of phase separation plays an important role in determining these functionalities, and the objective of our study was to experimentally investigate the kinetics of the phase inversion of polymer solutions during membrane formation.

We present details of a novel microfluidic device that enables us to measure the phase separation kinetics of membrane dopes via video-microscopy. Our device furnishes a well-defined sample geometry and controlled atmosphere for in situ tracking of the phase separation process. We use this technique to quantify the phase separation kinetics of polyetherimide polymer solutions with different concentrations upon contact with an array of relevant nonsolvents. We hypothesize that the process is affected by the micro-rheological and thermodynamic properties of the polymer solution and nonsolvent. To support our hypotheses; we report experimental data on the effective diffusivity of the phase separation front as a function of membrane solution rheology and thermodynamics, i.e. the nonsolvent/solvent/polymer interaction parameter. We also present scaling models that incorporate variations in microstructure and thermodynamic properties of the solutions.

P>
E
n
t
r
y Office Word 97-2003 Document

MSWordDoc

Word.Document.8
ô9²qface="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"face="Symbol"