Controlled Synthesis And Properties Of Side Chain Liquid Crystalline Homopolymers And Diblock Copolymers Based On Triphenylene

In this dissertation, we have designed and synthesized a series of side chain liquidcrystalline homopolymers(PMPHT) and diblock copolymers(PS-b-PMPHT) based ontriphenylene. It mainly focused on the study of the effection of molecular weight onthe liquid crystalline behavior of homopolymers, and the limit of PMPHT on theliquid crystalline behavior of diblock copolymers. The main topics of this paper are asfollows:1. A series of triphenylene-based side chain liquid crystalline homopolymers:poly{methylacrylic acid-[6-(3,6,7,10,11-pentahexyloxy) triphenyleneoxy] hexyl ester}(PMPHT), were successfully synthesized via atom transfer radical polymerization(ATRP). The molecular characterizations of the homopolymers were performed with1H NMR and gel permeation chromatography(GPC). The phase structures andtransitions of the polymers were investigated by a combination of techniquesincluding thermo-gracimetric analysis(TGA), differential scanning calorimetry(DSC),polarized optical microscopy (POM), and one-dimensional wide-angle X-raydiffraction(1D-WAXD). The experimental results shows that the liquid crystallinephase behavior of PMPHT was greatly depended on the molecular weight.PMPHT-1~PMPHT-7can exhibit hexagonal columnar phase(ΦHN), and with theincrease of molecular weight, the phase transition temperature of homopolymersincreased gradually, and then remained unchanged.2. A series of triphenylene-based diblock copolymers: polystyrene-b-poly{methylacrylic acid-[6-(3,6,7,10,11-pentahexyloxy)triphenyleneoxy] hexyl ester}(PS-b-PMPHT), were successfully synthesized via ATRP. The molecular characterizationsof the macroinitiator and diblock copolymers were performed with1H NMR and gelpermeation chromatography(GPC). The phase structures and transitions of the diblockcopolymers were investigated by a combination of techniques including thermo-gracimetric analysis(TGA), differential scanning calorimetry(DSC), polarized opticalmicroscopy (POM), and one-dimensional wide-angle X-ray diffraction(1D-WAXD).The experimental results shows that the limite of PMPHT had a great influence onliquid crystalline phase behavior of diblock copolymers. When the limite of PMPHTcontent was low, diblock copolymer can’t exhibit liquid crystal phase structure. Withthe increase of the limite of PMPHT content, although PS-b-PMPHT can exhibitcolumnar phase structure, compared with PMPHT, the order and stability of the liquid crystal phase of PS-b-PMPHT reduced.In summary, the liquid crystalline phase behavior of PMPHT was greatly dependedon the molecular weight, and the limite of PMPHT had a great influence on liquidcrystalline phase behavior of diblock copolymers.