Search

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]

A series of highly fluorinated polymers were synthesized by copolymerization of 2,3,4,5,6-pentafluorostyrene (PFS) and fluorinated styrene derivate monomer (FSDM). Their chemical structure were confirmed by 1H NMR, 13C NMR, and 19F NMR spectra. The refractive index and cross-linking density of the polymers can be tuned and controlled by monitoring the feed ratio of comonomers. A series of negative-type low-molecular-weight fluorinated photoresists (NFPs) were prepared by composing of fluorinated polystyrene derivates (FPSDs), diphenyl iodonium salt as a photoacid generator (PAG) and solvent. The polymer films prepared from NFP by photocuring exhibited excellent chemical resistance and thermal stabilities ( Td ranged from 230.5 to 258.1 °C). A clear negative pattern was obtained through direct UV exposure and chemical development. For waveguides without upper cladding, the propagation loss of the channel waveguides was measured to be 0.25 dB/cm at 1550 nm. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 [ABSTRACT FROM AUTHOR]