RECEIVED Nov29g4)9 CwrlKey words: gas separations; inorganic membranes; membrane preparation and structure; microporous and porous membranes,. C02 removal

A model is developed to predict the magnitude and pattern of stress due to drying of polymer films. This model combines diffusion-and-convection equation with large deformation elasto-viscoplasticity, utilizing concentration dependent elastic and viscoplastic material properties to better represent the behavior of drying thin films.The results show that the highest stress occurs at film surface where the concentration depletion is the highest. The magnitude of this stress is induced by increasing mass transfer across the film surface but reduced by increasing diffusion coefficient. The edge effect is significant but local, limited to about four film thicknesses. Similarly, change in substrate induces extra stress.

L-Alanine polypeptide thin films were synthesized via atomic layer deposition (ALD). Instead of using an amino acid monomer as the precursor, an L-alanine amino acid derivatized with a protecting group was used to prevent self-polymerization, increase the vapor pressure, and allow linear cycle-by-cycle growth emblematic of ALD. The successful deposition of a conformal polypeptide film has been confirmed by FTIR, TEM, and Mass Spectrometry, and the ALD process has been extended to polyvaline.

Drying of gelatin films was studied by an in-situ cantilever beam method combined with spectroscopic ellipsometry, enabling measurement of the stress development, film shrinkage and compositional change during the drying process. Experiments are carried out under different drying conditions (such as drying extent variation, drying rate variation). The film experiences stress relaxation that indicates visco-elastic relaxation or plastic deformation happened during drying process. Plastic deformation is verified by carefully reversing the drying process, however, the plastic deformation accompanied by visco-elastic relaxation complicates the case of finding the value of the yield stress.