Influence of the crystalline structure stability in the wettability of poly-β-hydroxybutyrate:polyethylene glycol 6000 fiber mats treated by atmospheric-pressure plasma

Abstract

The polymers have a low adhesion capacity, and they even tend to have less wettability in the form of fiber mats than in the way of a smooth surface. In the present work, a series of polymeric fiber mats composed of poly-β-hydroxybutyrate (PHB) and polyethylene glycol 6000 (PEG) were treated with atmospheric-pressure plasma (APP) to increase their wettability. The morphology of the fibers was observed with Scanning Electron Microscopy, the Optical Emission Spectrum was obtained during the treatment of APP, and the Raman spectrum was measured before and immediately after the APP treatment. The aging effect in the fiber mats was studied at 1, 24, and 168 h after the APP treatment through measurements of water contact angle (WCA) and X-ray diffraction (XRD). We obtained fiber mats from PHB: PEG with WCA less than 40°, as well as a composite that retains its superhydrophilicity (WCA = 0°) until after 168 h of being treated with APP. We find through the analysis of the results of Raman and XRD, that the addition of PEG preserves the amorphous part and the β-form of PHB after APP, which stops the recovery of the hydrophobic tendency of PHB with the aging.