Papers by Keyword: Photografting

Abstract: The effect of the polypropylene fabric morphology on the grafting copolymerization of methacrylics in the aqueous solution under ultraviolet irradiation was investigated. The infrared spectra and the scanning electron microscopy images verified the successful grafting copolymerization of the two monomers, glycidyl methacrylate (GMA) and Hydroxyethyl methacrylate (HEMA), onto the three fabrics, the spunbonded polypropylene nonwovens (SB), the spunlaid-meltblown-spunlaid polypropylene nonwovens (SMS), and the polypropylene monofilament plain fabrics (MPF). The results showed that, the grafting degrees of the two monomers increase and then tend constant with irradiation time, while those increase with the increase of the monomer concentrations for all the fabrics. The tight texture structure and the well-stretched monofilament surfaces of the MPF fabrics retard the grafting to a great extent. The inner fluffy meltblown layer of SMS nonwovens favors the grafting as compared with the SB nonwovens.

Abstract: The surface topography of poly(ether ether ketone) (PEEK) film immobilized with heparin and Bovine Serum Albumin (BSA) was characterized via scanning electron microscopy (SEM). Compared with the unmodified film, the surface of modified film changed and become rough, which indirectly proved the successful introduction of monomer and biomolecule on PEEK

Abstract: The fabrication of polymer based microfluidic devices using the hot embossing technique and their surface modification for easy fluid flow through the devices has been a growing field of research. During hot embossing, the replication fidelity on polymer substrate not only depends on the processing parameters such as temperature, pressure and time but also on their chemical structure which affects their thermo-dependent viscoelastic properties. For copolymers such as cyclic olefin copolymer (COC) which comprises ethylene and norbornene units, such properties depend on their relative ethylene and norbornene content. We report in this paper, a systematic study of replication fidelity and surface modification on COC polymer with varying norbornene content from 65 to 82 wt%. Replication fidelity which includes the surface morphology and cross-section profiles of the microchannel were characterized using SEM and Confocal microscope respectively. The modified surface was evaluated using Fourier transform infrared spectroscopy (FTIR spectroscopy) and water contact angle measurement. It was observed that in hot embossing, higher norbornene content contributed to good replication fidelity at identical experimental conditions. Furthermore, it was observed that with increase in norbornene content, the grafting efficiency decreases resulting in poor surface modification.

Abstract: As a simple and useful approach, vapor-phase photografting acrylic acid was used to modify the surface of PET films. Catalyst of silver nanoparticles was distributed on the photografting PET films equably after reducing by ascorbic acid. Topography of the pristine, grafting and metallized PET films was characterized by scanning electron microscope (SEM). XRD and FTIR-ATR were also used to analyze the electroless plating copper layer and the grafting PET film respectively.

Abstract: Photografting of bifunctional photolinker on biocompatible amphiphilic copolymers, such as PCL-b-PEGs and PLGA-b-PEGs, has been developed as a practical and versatile strategy for the materials functionalisation. Depending on the copolymer nature (block length, % of crystallinity) and the experimental conditions we could selectively direct the grafting on the hydrophilic PEG segments. The resulting copolymers were further derivatized with molecules of interest (RGD-peptides, LDV-peptides, “home-made”peptidomimetics, mannose derivatives,…) by substitution of the O-succinimidyl ester of the photolinker. The derivatization rates were controlled by radiolabelling, colorimetric assay and XPS spectroscopy. The functionalized copolymers were used in the formulation of nanoparticles displaying the ligands on their outer-shell. This nanoparticulate system was successfully employed for the oral vectorisation of antigen and for the targeted delivery of an anticancer drug.

Abstract: Piperazinyl-amide derivatives of N--(3-trifluoromethyl-benzenesulfonyl)-L-arginine were synthesized as graftable thrombin inhibitors. Their biological activity was evaluated in vitro, against human -thrombin, and in blood coagulation assay. The piperazinyl-amide derivatives were found to inhibit the activity of -thrombin in the micromolar range. The designed molecules were fixed on poly(ethylene terephthalate) (PET), and poly(butylene terephthalate) (PBT) by wet chemistry treatment (activation of hydroxyl chain-ends) and photochemistry (nitrene insertion by photoactivation of aromatic azide). The protocols were validated by X-ray photoelectron spectroscopy (XPS) and by radiochemical assay (liquid scintillation counting, LSC).

Abstract: Lithium acrylate (LiAA) was applied as a functional monomer to modify the surface properties of polypropylene films via photografting polymerization in a precipitation reaction system. Two-step photografting polymerization technique was adopted with benzophenone (BP) as the photoinitiator and methanol as the solvent. ATR-FITR spectra proved the occurrence of grafting polymerization of LiAA on the substrate. Gravimetric analysis was performed to investigate the influences of some important factors on the photografting polymerization of LiAA. SEM was utilized to investigate the topography of the grafted film. The experimental results indicated that elongation of the irradiation time could increase the grafting yield (Yg) and Yg performed a maximum at a certain concentration of LiAA. SEM images showed that regular particles evenly dispersed on the surface of the grafted film.