Amphiphilic fibers based on polypropylene-g-poly(acrylic acid) by sequential photo-induced metal-free ATRP and electrospinning

Abstract

Abstract Undoubtedly, with the increasing awareness of the scientific community and the public, current trends are directing research to implement effective and combined yet nature friendly methodologies. Due to advantages such as adaptability and versatility, the combination of electrospinning and light is increasingly intriguing. This study proposes a new strategy for producing amphiphilic fibers from graft copolymer of polypropylene (PP) and poly (acrylic acid) (FPP-g-PAA). The first step includes the synthesis of copolymer containing PP main chain and poly (tertiary butyl acrylate) pendant groups (PP-g-PAA) via photo-induced metal-free ATRP (PIMF-ATRP) of tertiary butyl acrylate (t-BA) monomer with chlorinated polypropylene (PP-Cl) as a macro photo-initiator followed by acidolysis of t-BA units to acrylic acid moieties. In the second step, the PP-g-PAA is successful electrospun to fabricate the ultimate amphiphilic fibers. The chemical steps are monitored and confirmed by Fourier-transform infrared (FT-IR) and proton magnetic resonance (1H-NMR) spectroscopies, and gel permeation chromatography (GPC). Following the structural characterization, morphological and wetting properties are systematically determined with scanning electron microscopy (SEM) and water contact angle (WCA) measurement by depending on surface characteristics of the samples. Thermal behaviour of precursors and synthesized electrospun fibers has also been evaluated and compared by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The SEM images display that the achieved fibers were smooth and circular with the average diameters ranging from 3.3 µm up to 3.9 µm. After WCA measurements, it was elucidated that the hydrophobic nature of electrospun PP-g-PtBA was transformed into amphiphilic structure by hydrolysis of PtBA pendant groups. The reported approach is very encouraging and expected to trigger further development for scientists preparing various types of amphiphilic polyolefin fiber based materials.