MODIFICATION OF POLYHIDROXOBUTYRATE MEMBRANES WITH AIR AND I-BUTANE PLASMAS

VILLEGAS, M.-CASTRO V.E.-GOTTIFREDI, J.C

Bariloche - Argentina

Conferencia; 13th INTERNATIONL CONFERENCE ON SOLID FILMS AND SURFACE ( ICSFS-13); 2006

Membranes of Poly(hydroxybutyrate) (PHB), a microbiological produced thermoplastic, were prepared by solution-casting. These films were modified in a Radio Frequency (RF) plasma reactor with two different gases: air for plasma treatment and 1-butene for plasma deposition, in order to obtain membranes with modified wettability. Power and exposition time were changed during plasma modifications from 7.2 to 29.6 W and from 10 to 30 min, respectively. The effect of these parameters on films surface wettability was studied by measuring the contact angle (q ) and the surface free energy (ãS) was calculated. The morphology of the PHB membrane substrate was observed with the scanning electron microscope (SEM). It is shown that PHB membrane has a dense superficial skin and it is not rugose, which guarantee reliable contact angle measurements and a uniform deposition. All surface treatments with air increased the wettability as shown by lowering contact angles and the applied power did not play an important role. Up to 20 min, q decreases linearly with exposition time. The observed q reduction is about 2° per minute. Longer exposition times did not produce significant contact angle lowering. The deposition with 1-butene plasma decreased PHB membrane wettability, independently of the time or power applied.