Switchable hydrophobic/hydrophilic surface of electrospun poly (l-lactide) membranes obtained by CF4 microwave plasma treatment
Graphical abstract
Section snippets
1 Introduction
Microfibrous structures fabricated by electrospinning are of particular interest due to their high specific surface area, high porosity and excellent mechanical properties that make them ideal candidates for polymer scaffolds [1], [2], [3], [4]. However, since some polymer surfaces, such as poly (l-lactide) (PLLA), are hydrophobic and its insufficient reactive side-chain groups on surface usually lead to low performances [5], its further application is severely limited [2], [6], [7], [8].
Materials
PLLA (biopla 6202F) was purchased from Ningbo Global Biological Material Co., Ltd. Its number-average molecular weights are 1.1 × 105 g/mol. Chloroform and ethanol were purchased from Tianjin Weichen Chemical Reagent Co. Ltd. China.
Electrospinning
The electrospinning apparatus is schematically depicted in Fig. 1, where the main components are shown. PLLA was dissolved in a mixture of chloroform and ethanol (3:1, v/v) to prepare a 7 wt% solution, which was then loaded into a plastic syringe fitted with a stainless
Surface morphology and water contact angle
Surface morphologies of the untreated and CF4 plasma treated electrospun PLLA microfibrous membranes were observed by FESEM, which are illustrated in Fig. 3, Fig. 4, and the water contact angle measurements of untreated and CF4 plasma-treated electrospun PLLA micro-fibrous membranes are given in Fig. 5. As can be seen in Fig. 3a, the as-spun PLLA micro-fibrous membrane is a highly porous nonwoven material with an average diameter of 847 ± 200 nm. More in detail, it was found that the untreated
Conclusion
A facile method to control the surface wettability of electrospun PLLA microfibrous membrane via CF4 microwave plasma treatment is investigated in this study. According to water contact angle analysis, both hydrophobic and hydrophilic surface could be obtained by adjusting the plasma power and treatment time during the CF4 plasma treatment. Moreover, plasma power is crucial for the surface wettability of PLLA membranes. FESEM results demonstrated that CF4 plasma treatment caused etching on PLLA
Acknowledgments
The work was funded by the Petrochemical Joint Funds of National Natural Science Fund Committee - China National Petroleum Corporation (U1362108) and China Postdoctoral Science Foundation (2014T70217).
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