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An interpenetrating polymer network (IPN) structured antibacterial layer was prepared on dental base materials containing quaternary ammonium salt monomers (HMDQAs), polyurethane dimethacrylate oligomers (BIHs) and functionalized SiO2 nanoparticles using a one-step photo-crosslinking method. Scanning electron microscopy (SEM), atomic force microscopy (AFM), ultraviolet near-infrared visible spectrophotometry (UV-3600) and water contact angles were used to study the surface properties of the coatings. SiO2 nanoparticles changed the hydrophilicity of the cationic antimicrobial surface and increased its contact angle. Furthermore, the IPN coatings exhibited highly effective antibacterial activity on the modified dental base material, poly(methyl methacrylate) (PMMA), against Streptococcus mutans, which was evaluated by plate colony counting, optical density (OD), SEM and a live/dead assay. The MTT assay confirmed their biocompatibility. The IPN silicon complexed coating displayed good transparency, excellent antibacterial activity, and no cytotoxicity, which indicated enormous potential for the treatment of denture bases. [ABSTRACT FROM AUTHOR]

This paper presents a discussion of the vibration damping enhancement offered by using composites made of partially filled poly(urethane)/polyurea (PU/PUA) microcapsules and E51 epoxy resin (EP). Seven types of microcapsule (with a core mass fraction of about 60 wt%) were prepared in which the core materials were acrylate polymers with different glass transition temperature (Tg, −53.59 °C to 34.40 °C). Dynamic mechanical analysis measurements were performed to investigate the dynamic mechanical properties of the composites, such as storage modulus E′ and loss factor tan δ. The correlations between the dynamic mechanical properties and the Tg of the core material of the partially filled microcapsules were studied. The microcapsule concentration of 15.4 wt% was found to be more efficient in adjusting the tan δ and the Tα of the E51 epoxy. The MP60-4/EP composite reached the highest tan δmax value of 0.82. By controlling the Tg of the core material, the tan δ of composites at the low temperature region increased from 0.12 to 0.29 and the Tα ranged from 77.1 °C to 114.8 °C. [ABSTRACT FROM AUTHOR]

Liquid viscoelastic polymers are promising materials for vibration damping due to their superior damping properties. However, using liquid polymers as materials for this purpose is challenging because liquid polymers cannot be used as normal materials in their amorphous fluid state. This study reports polyurethane/polyurea (PU/PUA) microcapsules prepared using oil-in-water (O/W) emulsion and interfacial polymerization. The microcapsules were partially filled with silicone oil and used as a damping filler in an epoxy resin specimen. Dynamic mechanical analysis measurements (DMA) were performed to investigate the loss factor tan δ of the epoxy resin blended with the microcapsules. The DMA results indicated that the partially filled structure of the microcapsules could enhance the vibration absorbing property of the epoxy resin specimen, and the maximum loss factor (tan δ) increased from 0.38 to 0.79. The loss factor of the epoxy resin could be controlled by the core volume fraction and the concentration of the microcapsules in the epoxy resin. [ABSTRACT FROM AUTHOR]

In this study, we design and synthesize a novel photosensitive polyurethane material as a functional dielectric layer, which can adjust the crystallization of para-hexaphenyl (p-6P). The novel polymer is synthesized with a new monomer 2,2-bis(hydroxymethyl)butyl 4-cyanobenzoate (HM-4-CB), which contains benzene to provide crystal nucleus sites. The grain size and density of the p-6P crystal can be controlled by the content of HM-4-CB in the polymer structure. Therefore, this method can be used to regulate the grain size of semiconductor crystals and then to change the carrier mobility of the device. The results illustrate that with a suitable grain size of the p-6P semiconductor, excellent performance in terms of charge carrier mobility can be obtained. [ABSTRACT FROM AUTHOR]