Facile Synthesis of Polyhydroxylated Polybutadiene Derived from Hydroxyl-Terminated Polybutadiene via Thiol-Ene Click Reaction

Polyhydroxylated polybutadiene (PHPB) was synthesized via a thiol-ene click reaction between hydroxyl-terminated polybutadiene (HTPB) and 2-mercaptoethanol (ME) with 2,2’-azoisobutyronitrile (AIBN) as initiator. Effects of AIBN content, reaction time and temperature on the click reaction were investigated by determining hydroxyl value of the PHPB. The PHPB was characterized by FT-IR, ¹H-NMR, ¹³C-NMR and GPC. Relative reactivity of three types of C?C double bonds (1,2-vinyl, 1,4-cis and 1,4-trans units) in the HTPB reacting with the ME was discussed. The results showed that the optimal reaction conditions were that the AIBN content, reaction time and temperature were 2.0 wt%, 180 min and 70°C, respectively. Under these conditions, the hydroxyl value of the PHPB was 3.12 mmol·g^?1 when the HTPB/ME mass ratio was 10:2. All three types of C?C double bonds in the HTPB could react with the ME and the reactivity order was: 1,2-vinyl unit > 1,4-cis unit > 1,4-trans unit.     

Synthesis and study of azo dye compounds: variation of mesogenic behaviour with length of alkyl chains

The mesogenic behaviours of two azo dye liquid crystals, 1 and 4, differ because of the different length of terminal alkyl chains; azo dye 1 shows a SmB phase, azo dye 4 shows nematic and SmA phases during thermal processing. The molecular stackings of these two azo dye liquid crystals are compared on the basis of crystallographic studies to explain such unexpected mesogenic behaviour.     

A FACILE APPROACH FOR THE SYNTHESIS OF α -HALOGENATED ALKYLIDENEDIPHOSPHONATES BY REACTION OF ALKYLLITHIUM WITH CHLOROPHOSPHATE AND HALOGEN REAGENT

Alkyllithium reacts with chlorophosphate to generate the α -lithio- alkylidenediphosphonate, which further reacts with halogen reagents to afford corresponding α -halogenated alkylidenediphosphonates.     

New synthetic routes to the kainoids: a synthesis of kainic acid and its analogues

New approaches to the synthesis of kainic acid and its analogues are presented. Two distinctly different approaches are described; the former utilised an intermolecular nitrile oxide addition to a homochiral substrate to furnish epikainate models and the second utilised amino acid chemistry to secure kainic acid.     

Representation of Integers by Ternary Quadric Forms

In this paper we give a formula for the number of representations of some square-free integers by certain ternary quadratic forms and estimate the lower bound of the 2-power appearing in this number. Supported by NSFC and RFDP.     

Molecular engineering leading to better processability of conjugated chromophores: The optical properties of new soluble copolymers containing alternative oligo-octylthiophene and oligo-methylene blocks

A series of conjugated/non-conjugated copolymers and their corresponding oligomers were prepared and their optical and physical properties were investigated for understanding the merit of blocking the conjugated chromophores with non-conjugated spacers. It was found that compared to the oligomers, copolymers have the advantages of amorphous nature, high thermal stability, and good thin film processability without sacrificing the quantum efficiency and purity of the emission color. Furthermore, based on the optical data of these copolymers and oligomers, the conjugation length of the polyoctylthiophene was estimated to be extended over 23-31 octylthiophene rings.