High‐contrast,high‐sensitivity aqueous base‐developable polynorbornene dielectric

The impact of multifunctional epoxy‐based additives on the crosslinking, photolithographic properties, and adhesion properties of a tetramethyl ammonium hydroxide developable, polynorbornene (PNB)‐based dielectric was investigated. Three different multifunctional epoxy additives were investigated: di‐functional, tri‐functional, and tetra‐functional epoxy compounds. The tetra‐functional epoxy crosslinker enhanced the UV absorbing properties of the polymer at 365 nm wavelength. It was found that the epoxy photo‐catalyst could be efficiently activated without a photosensitizer when the tetra‐functional epoxy was used. The polymer mixture with additional (3 wt %) tetra‐functional epoxy crosslinker and without a UV sensitizer showed improved sensitivity by a factor of 4.7 as compared to a polymer mixture containing the same number of equivalents of non‐UV sensitive epoxy with a UV sensitizer. The contrast improved from 7.4 for the polymer mixture with non‐UV absorbing epoxy and a UV sensitizer to 33.4 for the new formulation with 3 wt % tetra‐functional epoxy and no UV sensitizer. The addition of the tetra‐functional epoxy crosslinker also improved the polymer‐to‐substrate adhesion, which permitted longer development times, and allowed the fabrication of high‐aspect‐ratio structures. Hollow‐core pillars were fabricated in 96‐µm thick polymer films with a depth‐to‐width aspect‐ratio of 14 : 1. The degree of crosslinking in the cured films was studied by nanoindentation and swelling measurements. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Telechelic polymers by living and controlled/living polymerization methods

Telechelic polymers, defined as macromolecules that contain two reactive end groups, are used as cross-linkers, chain extenders, and important building blocks for various macromolecular structures, including block and graft copolymers, star, hyperbranched or dendritic polymers. This review article describes the general techniques for the preparation of telechelic polymers by living and controlled/living polymerization methods; namely atom transfer radical polymerization, nitroxide mediated radical polymerization, reversible addition-fragmentation chain transfer polymerization, iniferters, iodine transfer polymerization, cobalt mediated radical polymerization, organotellurium-, organostibine-, organobismuthine-mediated living radical polymerization, living anionic polymerization, living cationic polymerization, and ring opening metathesis polymerization. The efficient click reactions for the synthesis of telechelic polymers are also presented.     

磷氮硼(PNB)系催化剂处理对粘胶纤维热裂解行为的影响

催化剂是制备粘胶炭纤维的关键之一，利用含硼、含磷氮和含磷氮硼三种物质作为制备炭纤维的催化剂，通过TG-MS手段分析了三种催化剂对粘胶纤维在惰性气氛下热解行为的影响。结果表明：三种催化剂的加入均使粘胶纤维的裂解反应向低温侧移动，并大大提高了粘胶纤维在600℃时的热解收率，三种催化剂均能提高粘胶纤维裂解产物中水和二氧化碳的生成；含硼类催化剂不能抑制焦油、醛酮和呋喃类物质的生成，而含磷氮和含磷氮硼催化剂对焦油、醛酮和呋喃类物质的抑制作用较强。磷氮硼并用时的催化效果优于单独使用磷氮或硼，二者对粘胶纤维的裂解具有协同催化作用。