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Mobility is an important parameter to estimate the performance of organic thin‐film transistors, one of the key factors affecting the mobility is the first several semiconductors molecular layers near the insulator surface. A strategy is proposed to introduce aromatic‐rings in the gate insulating layer to modulate the growth of pentacene, thus a series of aryl group containing polymers by reversible‐addition‐fragmentation chain‐transfer polymerization is synthesized for the preparation of organic thin‐film transistor insulators. The semiconductor layer is evaporated on the polymer insulators at room temperature. As the inducing function of the aromatic ring, greater weak interactions between dielectric materials and semiconductors by simulation, which makes the initial pentacene layer weak epitaxial growth, therefore pentacene could form better morphology, especially larger crystal domains and uniform thin‐film continuity. The results show that precision design and synthesis of polymer insulator layers provide new methods to achieve high performance of organic thin‐film transistors with easier fabricating process. [ABSTRACT FROM AUTHOR]

In this study, polyurethane dimethacrylate (PUDMA) was synthetized from different components and incorporated into a direct resin composite restoration system with the aim to buffer tooth–resin interfacial stresses and maintain the marginal adaptation. The tensile strength, elongation at fracture (ε), and thermal stability of the PUDMA layer were characterized, showing a tensile strength of 22 MPa, an ε of 112%, and a thermal decomposition temperature of about 282°C. In addition, the degree of conversion, water sorption/solubility, hydrophobicity, microtensile bond strength (μTBS), marginal leakage, and cytotoxicity in vitro were evaluated for the PUDMA layer. The data were analyzed using one‐way ANOVA, except for leakage depths (which were analyzed using the Wilcoxon paired‐rank test). The level of significance was set at 0.05. Compared with dental adhesives, PUDMA displayed a higher degree of conversion, lower water sorption/solubility, and improved hydrophobicity and biocompatibility in vitro. After thermocycling, the μTBS of the restoration system containing PUDMA had increased compared with the μTBS at 24 h. Restorations containing PUDMA showed lower leakage depths than those which did not contain PUDMA. In conclusion, because of its hydrophobic and elastic nature, the PUDMA layer, when used as an intermediate between tooth and resin restoratives, may buffer interfacial stresses, improve the stability and durability of the bonding interface, and reduce microleakage. [ABSTRACT FROM AUTHOR]

Low-voltage operation in organic thin-film transistors (OTFTs) is desirable for low power applications and portable electronics. Using polymer materials with a high dielectric constant (high-k) as gate dielectrics is an important way to realize low-voltage operating OTFTs. In this work, we synthesized a class of novel copolymers, which exhibit a high-k up to 7–10 depending on the content of cyclic carbonate. These copolymer materials are easily processed into films with a smooth surface topography and without pinholes by simple spin-coating. Moreover, they show excellent insulation properties with low leakage current densities (<7 × 10−7 A cm−2 at 100 MV m−1) and small dielectric loss (<0.03, 102–105 Hz). Meanwhile, cross-linked copolymers also display good flexibility and solvent resistance. To inspect their application prospects in low-voltage operating OTFTs, these copolymer films were employed as gate dielectrics to build p- and n-type OTFTs with C10-DNTT and F16CuPc as active layers, respectively. As a result, our OTFTs exhibit good field-effect properties at low operating voltages below 10 V, with high hole and electron mobility up to 9.7 and 0.005 cm2 V−1 s−1 on average, respectively. Our results indicate a strategy on design of high-k polymer materials as gate dielectrics to pursue low-voltage operating OTFTs. [ABSTRACT FROM AUTHOR]

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]

In this work, polyimide-based novel polymer dielectric materials, containing a cross-linkable olefin group and a long alkyl chain with biphenyl, were designed and synthesized by a mild chemical synthesis method to avoid thermal imidization so that they can be widely utilized. The two novel polyimide materials show good thermal stability, pinhole-free dense film morphologies, low leakage current densities (＜2 × 10−7 A cm−2 at 150 MV m−1) and small dielectric loss values (＜0.02, 103 to 107 Hz), which provides excellent insulating properties. In order to explore their possibility as dielectric layers, the bottom-gate top-contact para-hexaphenyl (p-6P)/vanadyl-phthalocyanine (VOPc) OTFTs with these two polyimide polymer thin films as the dielectric layers exhibit excellent device performance with a high charge carrier mobility of 1.11 and 1.23 cm2 V−1 s−1, current on/off ratio ＞5 × 105, and relatively low threshold voltage (10 and 3.6 V, respectively). [ABSTRACT FROM AUTHOR]

A series of acrylate group terminated fluorinated polycarbonates containing 4,4-cyclohexylidenebis phenol (BPZ) (AF-Z-PC MAs) or dodecyl chains (AF-Ali-PC MAs) were synthesized. These polymers were further doped with chromophores and crosslinked under a UV lamp. With these doped polymers as the functional layer, we successfully obtained straight and Y structure waveguides by a direct writing method for electro-optical modulator devices. These cross-linked polymers displayed good thermal stability, low optical loss and a high refractive index. In addition, after polarization, the electrooptic coefficients r33 of the doped films were 10 pm V−1 and 9 pm V−1, measured by the Teng–Man method, respectively. The results showed that the direct writing method was a simple and effective way to fabricate Mach–Zehnder structure waveguides and these new macroacrylate terminated polycarbonates had great potential in the application of electro-optical modulator devices. [ABSTRACT FROM AUTHOR]

In this study we evaluated dual-cure polyurethanes (PUs) as dental adhesives and investigated their effect on the durability of the resin–dentin bonding interface. Different novel photopolymerizable and moisture-curable PUs based on polyester polyol, polyether polyol, and hydroxyethyl methacrylates (HEMAs) were prepared, and their structural characteristics were evaluated by Fourier transform infrared spectroscopy. The tensile strength, elongation at break, and water sorption/solubility of the PU adhesives and the application for bonding with dentin were evaluated. The water sorption and solubility of the PU adhesives were significantly lower than those of two commercial control groups. The bond strength of the PU adhesives after 30 days of storage increased compared with their immediate bond strength, and the microleakage detection of Class V restorations showed less occurrence of marginal leakage compared with the commercial control groups. Cytotoxicity testing has shown that the PU adhesives have low toxicity to pulp cells. The results of this study may shift the future research focus of composite resin dental restoratives from original rigid bonding of the interface to a flexible bonding based on the use of PU adhesives. This may become a new strategy for decreasing the occurrence of microleakage and improving the durability of the bonding interface. [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]