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A novel kind of incompletely condensed polyhedral oligomeric silsesquioxane (TAP-POSS) containing allyl groups was successfully synthesized, and its structure was characterized by fourier transform infrared, nuclear magnetic resonance (H-NMR and Si-NMR) and X-ray diffraction. In addition, TAP-POSS was hybridized with 2,2′-diallylbisphenol A (DBA)-modified 4,4′-bismaleimidodiphenylmethane (BDM) resin to develop a new kind of hybrids with simultaneously improved thermal stability and dielectric properties. Compared with BDM/DBA resin, the BDM/DBA/TAP-POSS hybrids have obviously increased thermal resistance reflected by the increased glass transition temperature ( T) and char yield at high temperature. For example, the T of modified BDM/DBA resin with only 3.0 wt% TAP-POSS is 330 °C, which is 36 °C higher than that of pure BDM/DBA resin. On the other hand, the dielectric properties over wide frequency and temperature ranges are thoroughly investigated, and results show that the dielectric constant and loss of all hybrids are not only lower than those of BDM/DBA resin over the whole frequency and temperature ranges tested, but also exhibit smaller dependence on temperature and frequency. These phenomena can be explained from the variety of cross-linked structure induced by the presence of TAP-POSS. The outstanding integrated properties of BDM/DBA/TAP-POSS hybrids suggest that TAP-POSS has advantages over conventional POSS, thus the method proposed herein is a new approach to develop high performance structural/functional materials for cutting-edge industries. [ABSTRACT FROM AUTHOR]

A new addition curable silicone resin (ASiR) system with excellent dielectric and thermal properties was developed, which consists of only two components: poly(methylphenylvinylsiloxane) (PMPVSi) and an end-capped hydrogen-functionalized hyperbranched polysiloxane (EHFHPSi). PMPVSi is synthesized by a green and controllable process; EHFHPSi is first synthesized via A2 + B3 approach, and then end-capped by hexamethyldisiloxane (HMDS). Three formulations were designed to investigate the optimum stoichiometry. Results show that cured ASiR resins have greatly different dielectric and thermal properties because of the different chemical structure of cured networks resulting from the different stoichiometries. The resin with a suitable stoichiometry has not only excellent dielectric properties including extremely low dielectric constant (2.96 at 1 Hz) and loss (0.0003 at 1 Hz) as well as good stability on frequency, but also outstanding thermal resistance, exhibiting great potential to be used as a new kind of high-performance resins for many cutting-edge industries, especially the microelectronic and insulation fields. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Photosensitive resins used in three-dimensional (3D) printing are characterized by high forming precision and fast processing speed; however, they often possess poor mechanical properties and heat resistance. In this study, we report a photocurable bismaleimide ink with excellent comprehensive performance for stereolithography (SLA) 3D printing. First, the main chain of bismaleimide with an amino group (BDM) was synthesized, and then, the glycidyl methacrylate was grafted to the amino group to obtain the bismaleimide oligomer with an unsaturated double bond. The oligomers were combined with reaction diluents and photo-initiators to form photocurable inks that can be used for SLA 3D printing. The viscosity and curing behavior of the inks were studied, and the mechanical properties and heat resistance were tested. The tensile strength of 3D-printed samples based on BDM inks could reach 72.6 MPa (166% of that of commercial inks), glass transition temperature could reach 155 °C (205% of that of commercial inks), and energy storage modulus was 3625 MPa at 35 °C (327% of that of commercial inks). The maximum values of T-5%, T-50%, and Tmax of the 3D samples printed by BDM inks reached 351.5, 449.6, and 451.9 °C, respectively. These photocured BDM inks can be used to produce complex structural components and models with excellent mechanical and thermal properties, such as car parts, building models, and pipes. [ABSTRACT FROM AUTHOR]