Effect of crosslinking stage on photocrosslinking of benzophenone functionalized poly(2-ethyl-2-oxazoline) nanofibers obtained by aqueous electrospinning. (March 2019)

• Record Type: Journal Article
• Authors: Li, Yin; Vergaelen, Maarten; Schoolaert, Ella; Hoogenboom, Richard; De Clerck, Karen
• Is Part Of: European polymer journal. Volume 112(2019)
• Page Start: 24
• Page End: 30
• Publication Date: 2019-03
• Subjects: Electrospinning -- Poly(2-ethyl-2-oxazoline) -- Benzophenone -- UV-irradiation -- Crosslinking -- Nanofibers; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; Polymerization; Polymers; Periodicals; Electronic journals; 547.705
• DOI: 10.1016/j.eurpolymj.2018.12.030
• Languages: English
• ISSNs: 0014-3057

Abstract

Graphical abstract: Highlights: Functionalization of poly(2-ethyl-2-oxazline) with benzophenone to enable crosslinking. Green electrospinning of poly(2-ethyl-2-oxazoline) nanofibers from water. Study of the effect of pre-, in situ, and post-crosslinking by UV-irradiation respectively before, during or after the electrospinning process. Different crosslinking stages provide variable crosslinking densities resulting in tunable water-stability of nanofibrous membranes, of great interest to biomedical applications. Abstract: In this study, benzophenone was introduced onto partially hydrolyzed poly(2-ethyl-2-oxazoline) (PEtOx-PEI) to prepare a poly(2-ethyl-2-oxazoline)-benzophenone (PEtOx-BP) copolymer, which was used to produce water stable nanofibers via aqueous electrospinning and photocrosslinking. Three different ultraviolet (UV) irradiation methods, i.e. pre-crosslinking before electrospinning, in-situ crosslinking during electrospinning and post-crosslinking after electrospinning, were used to prepare crosslinked nanofibers. The influence of UV-irradiation at these different stages of the nanofiber production process was investigated in terms of alterations in viscosity, nanofiber morphology and water stability of the fibers. It was shown that pre-crosslinking the polymer solutions had a great influence on the solution viscosity which could both positively or negatively alter the stability of the electrospinning process. Whereas the strategy of crosslinking nanofibers during the production process did not lead to uniform nor water-stable nanofibers, the pre-crosslinking and post-crosslinking strategies greatly increased the water stability of the nanofibers. In both techniques the crosslinking density and therefore water solubility can be easily tuned by manipulating the polymer concentration, UV-irradiation time and membrane thickness. Complete insolubility, i.e. the formation of crosslinked networks, was achieved by the post-crosslinking strategy. This work provides straightforward methods to increase the water stability of the PEtOx nanofibers, which will definitely be of great value to biomedical applications such as drug delivery and tissue engineering.