Facile preparation of polyolefin-based amphiphilic graft copolymer fibers by combination of photoinduced graft copolymerization and electrospinning.

A novel amphiphilic graft copolymer possessing polypropylene (PP) main chain and poly(oligoethylene glycol methacrylate) (POEGMA) pendant units was synthesized starting from chlorinated polypropylene (PP-Cl), and characterized. PP-Cl produced macroradicals at chlorine bounded carbon atoms by visible light irradiation in the presence of dimanganese decacarbonyl [Mn2(CO)10] and initiated the free-radical photopolymerization of an acrylate monomer, namely oligoethylene glycol methacrylate (OEGMA). Furthermore, fiber formation ability of PP-g-POEGMA was tested by electrospinning technique. The chemical structure and some features of the corresponding amphiphilic graft copolymer PP-g-POEGMA was characterized by implementing spectral (FT-IR, 1H-NMR), chromatographic (GPC), morphological (SEM), water wettability (WCA), and thermal (TGA) analyses. It was clear from the SEM results that the average diameter of the obtained microfibers decreased with the incorporation of POEGMA segments onto the PP-Cl main chain. Based on WCA measurements, PP-g-POEGMA was determined as more wettable than PP-Cl due to its hydrophilic POEGMA building blocks. This facile procedure could be utilized to achieve the amphiphilic commercial polymers for potential bioapplications such as drug delivery.

Preparation of a sustainable bio-copolymer based on Luffa cylindrica cellulose and poly(ɛ-caprolactone) for bioplastic applications.

In this research, a bio-based graft copolymer (LCC-g-PCL) based on the cellulose of Luffa cylindrica (LCC) main chain possessing poly(ɛ-caprolactone) (PCL) pendant groups is synthesized through a grafting from approach via ring-opening polymerization (ROP). For this purpose, LCC, extracted from luffa sponges by combined method, is utilized for ROP of ɛ-caprolactone (ɛ-CL) as a macro-initiator in the presence of stannous octoate as a catalyst. Fourier transform infrared (FT-IR), proton and carbon nuclear magnetic resonance (1H NMR and 13C NMR) spectroscopies are utilized to structurally indicate the success of ROP, while the achieved graft copolymer is analyzed in detail by comparing with LCC and neat PCL in terms of wettability, thermal and degradation behaviors by conducting water contact angle (WCA) measurements, thermogravimetric and differential scanning calorimetry analyses (TGA and DSC) and in vitro both hydrolytic and enzymatic biodegradation tests, respectively. The results of conducted tests show that the incorporation of PCL groups on LCC provide the increasing hydrophobicity. In addition, the degradation behavior of the LCC-g-PCL copolymer is found to be more pronounced under enzymatic medium rather than hydrolytic conditions. It is anticipated from the results that LCC-g-PCL can be a potential eco-friendly material particularly in bioplastic industry.

Visible light induced step-growth polymerization by electrophilic aromatic substitution reactions.

A novel visible light induced step-growth polymerization to form poly(phenylene methylene) by electrophilic aromatic substitution reactions is described. The effect of different nucleophilic aromatic molecules on polymerization has been investigated. The possibility of combining step-growth polymerization with conventional free radical and free radical promoted cationic polymerizations through photoinduced chain-end activation has been demonstrated. Highly fluorescent fibers of the resulting block copolymers were obtained using the electrospinning technique. The versatile photoinduced step-growth polymerization process reported herein paves the way for a new generation of polycondensates and their combination with chain polymers that cannot be obtained by conventional methods.

In situ preparation of hetero-polymers/clay nanocomposites by CUAAC click chemistry.

A series of polymer/clay nanocomposites containing mechanistically two different polymers, poly(ethylene glycol) (PEG) and poly(epsilon caprolactone) (PCL), were prepared by simultaneous copper(I)-catalyzed alkyne-azide cycloaddition click reactions. Both clickable polymers, PEG-Alkyne and PCL-Alkyne, were simultaneously clicked on to azide-functional montmorillonite (MMT-N3) nanoclay to get corresponding PEG-PCL/MMT nanocomposites. The chemical structures of the resulting nanocomposites were verified by following azide and silicone-oxygen bands using FT-IR and characteristic bands of PEG and PCL segments using 1H-NMR spectroscopy. The combined XRD and TEM analysis confirmed that all PEG-PCL/MMT nanocomposites had partially exfoliated/intercalated morphologies. In addition, the increase of MMT-N3 loading not only improved the onset and maximum degradation temperatures of the nanocomposites but also their char yields. Furthermore, the incorporation of MMT-N3 in the polymer matrix did not significantly influence the crystallization behavior of both PEG and PCL segments.

Synthesis of self-curable polysulfone containing pendant benzoxazine units via CuAAC click chemistry.

Synthesis, characterization, and properties of new thermally curable polysulfone containing benzoxazine moieties in the side chain were investigated. First, chloromethylation and subsequent azidation processes were performed to form polysulfone containing pendant clickable azide groups. Independently, antagonist 3,4-dihydro-3-(prop-2-ynyl)-2H-benzoxazine was prepared by using paraformaldehyde, phenol and propargylamine. The following copper(I) catalyzed azide-alkyne cycloaddition click reaction was applied to obtain self-curable polysulfone with pendant benzoxazine units. The polymer and intermediates at various stages were characterized by 1H-NMR, 13C-NMR and FT-IR spectroscopies. The thermal properties and curing behavior of final polymer were investigated by differential scanning calorimetry and thermal gravimetric analysis. Compared to the neat polysulfone, the obtained polymers exhibited thermally more stable polymers.