A new superbase, the cyclic trimeric phosphazene base (CTPB), was prepared with high yield and purity. In the presence of alcohol, the CTPB serves as a highly efficient organocatalyst for ring-opening polymerization of the "non-polymerizable" γ-butyrolactone to offer well-defined poly(γ-butyrolactone) with high conversions (up to 98 %) at -60 °C. The produced polymers have high molecular weights (up to 22.9 kg mol ) and low polydispersity distributions (1.27-1.50). NMR analysis of initiation process and the structural analysis of resulting polymers by MALDI-TOF suggest a mechanism involving an activating initiator which leads only to linear polymers with BnO/H chain ends.
Abstract. Wireless vehicular networks operating on the dedicated short-range communications (DSRC) frequency bands are the key enabling technologies for the emerging market of intelligent transport system (ITS). The wireless access in vehicular environments (WAVE) is significantly different from the Wi-Fi and cellular wireless networking environments. The specifications defined by IEEE802.11P and IEEE1609 represent the most mature set of standards for DSRC/WAVE networks. This paper provides an overview of the current state of the art, and analyses the potential differences between application requirements and what can be offered by the current WAVE solutions. It is shown that the current solutions may be inadequate for large-scale deployment. The primary challenge is to develop scalable, robust, low-latency and highthroughput technologies for safety applications that will significantly reduce collisions and save lives and property loss. Further research ideas are proposed to address this challenge.
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