Spray-coated and solution-cast ethylcellulose pseudolatex membranes

Membranes of dibutyl sebacate (DBS) plasticized ethylcellulose pseudolatex were prepared by spray-coating and solution-casting methods for the studies of their transport and mechanical properties. The structure of sprayed mem branes was more porous than that of cast membranes, so the sprayed membrane s were more permeable than the cast membranes. The permeabilities of drug o r water vapor through sprayed membranes decreased with increasing plasticiz er concentration; on the contrary, those through cast membranes increased w ith increasing plasticizer concentration. The diffusion through pores accou nts for the transport through sprayed membranes, while the solution-diffusi on through plasticized polymer phase may become an important role for that through the cast membranes. Mechanically, the sprayed membranes were harder and more brittle than the cast membranes of similar formulation, but membr anes prepared from both methods possessed similar breaking tensile strength . The tensile strength and Young's modulus were reduced and the elongation was improved with increasing plasticizer concentration for both kinds of me mbranes. The sprayed membranes would become less permeable and tougher afte r the post thermal treatment as the degree of coalescence between the latex particles in the membranes was enhanced. (C) 1999 Elsevier Science B.V. Al l rights reserved.