A fundamental study on the sterilization of thiol‐ene/acrylate polymers for biomedical applications is presented. These polymer networks belong to the emerging field of shape memory polymers and have the capability to undergo softening after insertion into the body. The impact of various sterilization methods, such as radiation, steam, and ethylene oxide on the thermomechanical properties of these stimuli responsive materials is investigated. Time and temperature dependent thermomechanical properties of sterilized and nonsterilized samples are determined by means of dynamic mechanical analysis in an aqueous environment to allow testing of polymers in phosphate buffered saline. The findings show that ethylene oxide sterilization is appropriate for thiol‐ene and thiol‐ene/acrylate based shape memory polymers. This method does not adversely affect thermomechanical and self‐softening properties and after sterilization, endotoxin levels remain below the thresholds recommended in the FDA Guidance.
We report here the self-assembly
studies of 22 polycarbodiimides
(PCDs) in complex morphologies such as fibers, looped fibers, fibrous
networks, ribbons, worm-like aggregates, toroidal structures, and
craters that were examined by combination of TMAFM, TEM, SEM, and
powder XRD methods as well as semiempirical modeling. Morphology characterization
in the thin film (TMAFM, TEM) and in bulk (SEM, pXRD) revealed the
formation of fiber-like aggregates assembled from the bundles of individual
helices. In certain cases superhelical motifs of both right- and left-handed
screw senses were identified. It seemed likely that the great variety
of morphologies observed is a result of extensive hydrophobic side
chain/side chain interactions of the singular polycarbodiimide strands.
Hedyotis corymbosa (L) (Khetpapra in Bengali), a weedy herb of Rubiaceae family is used as a traditional medicine in Bangladesh for the treatment of Jaundice and other liver disorders. In the present study, hepatoprotective and anti-bacterial activity of ethanolic extract of the herb and ursolic acid isolated from it were investigated against paracetamol induced hepatotoxicity in Long Evan's rats and also against some selective gram positive and ten gram negative bacteria. The ethanolic extract of the plant showed significant hepatoprotective effect as evident by decreased serum enzyme levels, SGPT, SGOT, SAKP and SBIL, and also by normal histological architecture of the liver when compared to the paracetamol treated group. Moreover, ethanolic extract, n-hexane fraction and ursolic acid showed maximum activity of 18, 19, 21 mm against Sarcina lutea, Klebsiella pneumonia and Staphylococcus aureus respectively when compared with standard kanamycin disc (30 µgm/disc). These results thus support Hedyotis corymbosa and ursolic acid as hepatoprotective and antibacterial agent.
Fused filament fabrication (FFF) is the most common form of additive manufacturing. Most FFF materials are variants of commercially available engineering plastics. Their performance when printed can widely vary, thus there is an increasing volume of research on alternative materials with thermal and mechanical performance optimized for FFF. In this work, thiol-isocyanate polymerization is used for the development of a one-pot synthesis for polythiourethane thermoplastics for tough three-dimensional (3D) printing applications. The thiol-isocyanate reaction mechanism allows for rapid polymer synthesis with minimal byproduct formation and few limitations on reaction conditions. The resulting elastomer has high toughness and a low melting point, making it favorable for use as a 3D printing filament. The elastomer outperforms commercial filaments in tension when printed. Considering the rapid advancement of additive manufacturing and the limitations of many engineering polymers with the 3D printing process, these results are encouraging for the development of bespoke 3D printing thermoplastics. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45574.
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