Mechanism Study of the Polymerization of Polyamide 56: Reaction Kinetics and Process Parameters.

Polyamide 56 (PA56) has gained significant attention in the academic field due to its remarkable mechanical and thermal properties as a highly efficient and versatile biobased material. Its superior moisture absorption property also makes it a unique advantage in the realm of fiber textiles. However, despite extensive investigations on PA56's molecular and aggregate state structure, as well as processing modifications, little attention has been paid to its polymerization mechanism. Herein, the influence of temperature and time on PA56's polycondensation reaction is detailed studied by end-group titration and carbon nuclear magnetic resonance (NMR) techniques. The reaction kinetics equations for the pre-polymerization and vacuum melt-polymerization stages of PA56 are established, and possible side reactions during the polycondensation process are analyzed. By optimizing the reaction process based on kinetic characteristics, PA56 resin with superior comprehensive properties (melting temperature of 252.6 °C, degradation temperature of 371.6 °C, and tensile strength of 75 MPa) is obtained. The findings provide theoretical support for the industrial production of high-quality biobased PA56.

Synthesis and anti-tumor activities of novel oxazinyl isoflavonoids.

The design, synthesis and biological evaluation of a novel series of oxazinyl isoflavonoids is described. Several analogs were shown to exhibit growth inhibitory effects against SKOV-3, DU-145 and HL-60 human colon cancer cell lines with IC(50) values in the micromolar range. The cellular potency of compounds 7e and 12h were found to have greater in vitro inhibitory activities than phenoxodiol, the parental compound currently in late-stage clinical trials for the treatment of cancer. The results shown are suitable for further lead optimization.

Synthesis of photothermal antimicrobial cotton gauze using AuNPs as photothermal transduction agents.

Cotton gauze has been used as a wound dressing since the 19th century, and still plays an important role in current clinical therapies. However, the antimicrobial ability of cotton gauze is limited. In this work, gold nanoparticles (AuNPs) were used as photothermal transduction agents to synthesize modified photothermal antimicrobial cotton gauze. The modified cotton gauze was synthesized by immersing and heating the clinical cotton gauze with AuNPs solution. XPS, ICP-OES, FTIR, XRD and SEM characterizations confirmed that AuNPs were successfully decorated on the surface of cotton gauzes. Besides, the mechanical properties, air and water vapour permeability performance of cotton gauze were not changed after modification. Photothermal antimicrobial experiments confirmed that AuNPs modified on the cotton gauze could convert light to heat, inducing rapid temperature increase of the cotton gauze. And the heat could kill microbial cells permeated in the modified cotton gauze, giving it the potential of being used for photothermal antimicrobial therapy.