【作者】 谌烈；

【导师】 陈义旺；

【作者基本信息】 南昌大学 ， 材料物理与化学， 2009， 博士

【摘要】 液晶共轭聚合物（LCCP）是近几年发展起来的一类新型的功能高分子,它兼有液晶聚合物和共轭聚合物的双重特性,集液晶性和发光性于一身。利用液晶基元在外力场下能自发取向的特点,可以有效地提高和控制高分子主链的共轭长度,从而得到具有优良的光、电、磁学性能的有机高分子材料。由于三联苯具有良好的致晶作用和发光性能,本文将液晶基元同时设计成发光基团,合成了一系列分别基于聚炔、聚噻吩和聚苯不同共轭主链的含三联苯液晶基元的侧链型液晶共轭聚合物,研究了其结构和性能之间的关系,特别是三联苯液晶基元既作为液晶基元又作为发光基团对聚合物液晶性能、热性能和发光性能的影响。本文设计合成了两种新型含氰基三联苯双取代乙炔单体4-[（4’-氰基-4-三联苯基）氧基]-1-丁基-1-丁炔A（bu）TPhCN和3-[（4’-氰基-4-三联苯基）氧基]-1-苯-1-丙炔A（Ph）TPhCN。以WCl₆/PhSn₄为催化剂成功聚合了含丁基取代基的单体A（bu）TPhCN,获得了含氰基三联苯液晶基元双取代聚乙炔PA（bu）TPhCN。由于体积效应,含苯基取代基的单体A（Ph）TPhCN的聚合反应没有获得成功。利用红外光谱（FT-IR）、核磁共振（¹H NMR）对单体和聚合物的结构进行了表征,利用差示扫描量热仪（DSC）、带热带的偏光显微镜（POM）、X射线衍射（XRD）、紫外光谱（UV）和荧光光谱（PL）对单体和聚合物的液晶性能进行了研究。结果表明:单体和聚合物均具有预期结构。两种单体都呈现互变的近晶相（SmA）,由于主链与液晶基元之间的偶合作用,使得聚合物呈现出向列相（N）。同时,氰基三联苯的存在赋予了单体和聚合物很强的紫外吸收和良好的光致发光性能,其中聚合物PA（bu）TPhCN光致发光最大发射峰波长为411 nm。通过Suzuki偶联和酯化等反应,还合成了一类基于不同末端基（-CN和-OCH₃）含有三联苯液晶基元的双取代丙炔酸酯单体[C₅H₁₁C≡CCOO-terphenyl-R; R=CN, A（COO）TPhCN; R=OCH₃, A（COO）TPhOMe],在这类单体中,液晶基元通过酯键直接和乙炔三键相连。研究了单体的聚合反应,研究了三联苯液晶基元和末端基对其热性能、液晶性能和发光性能的影响。结果表明:利用MoCl₅-和WCl₆-类催化聚合单体,反应没有成功。这是由于结构中存在过多的极性基团,导致了催化剂中毒,同时,大体积的三联苯和烷基双取代基的位阻效应进一步遏制了反应的进行。含氰基末端基的单体A（COO）TPhCN具有单向向列相液晶态,而含甲氧基单体A（COO）TPhOMe呈现出互变的向列相和SmA_d相。单体的紫外光谱和荧光光谱显示出三联苯赋予了单体很强的紫外吸收和光致发光性能,此外,单体的紫外吸收和发光性能还受末端基结构的影响,电子推吸效应有助于提高其紫外吸收和发光性能。将三联苯液晶基元连接于聚噻吩主链3位上,合成了一类基于不同末端基含有三联苯液晶基元的发光性聚噻吩衍生物{-[Thiopheneyl-CH₂COO-terphenyl-R]_n-; R=CN, PT（0）TPhCN; R=OCH₃, PT（0）TPhOMe; -[Thiopheneyl-CH₂COO-（CH₂）₆-O-terphenyl-CN]_n-, PT（6）TPhCN}。探讨了三联苯液晶基元、间隔基长度和末端基种类对单体和聚合物性能的影响。利用红外光谱（FT-IR）、核磁共振（¹HNMR）对单体和聚合物的结构进行了表征,证实了单体和聚合物具有预期结构。所有聚合物均具有良好的溶解性能和较高的热稳定性,其热分解温度可达300℃以上。单体都呈现出良好的液晶性能,但聚合以后,具有短间隔基的聚合物PT（0）TPhOMe和PT（0）TPhCN失去了液晶性能,而具有长间隔基的聚合物PT（6）TPhCN却呈现出SmA_d相,这是由于长间隔基可降低主链与侧链之间的偶合作用,有助于液晶基元的有序排列。三联苯的存在还赋予了聚合物良好的光致发光性能,且随着间隔基的增长和电子推吸效应的增加而增强。以聚对苯为主链,将三联苯液晶基元以侧链形式连接于主链上,得到一类含有不同间隔基长度和末端基种类（-CN和-OCH₃）的聚对苯类液晶共轭聚合物{-[C₆H₃-COO-terphenyl-CN]_n-, PP（0）TPhCN; -[C₆H₃-COO-（CH₂）₆-O-terphenyl-R]_n-; R=CN, PP（6）TPhCN; R=OCH₃, PP（6）TPhOMe}。研究发现,单体和聚合物均呈现出互变的液晶相,即使是以短的酯基为间隔基的聚合物PP（0）TPhCN也具有互变的近晶相。在紫外光激发下,聚合物都具有发蓝色光特性,其中具有长间隔和氰基末端基的聚合物PP（6）TPhCN,其光致发光波长可延伸到600nm的可见光区。另外,利用圆二色谱（CD）还研究了聚合物主链的二级结构,首次发现,由于大体积液晶基元的位阻效应和取向作用,液晶基元环绕主链进行取向的同时诱导聚合物的主链在长程范围内呈螺旋取向。计算机分子结构模拟也证实了,随着重复单元的增长,聚合物主链具有明显的螺旋取向。因此,不需引入任何手性基团,即可获得主链具有螺旋结构的聚合物,且具有短间隔基的聚合物PP（0）TPhCN相对于具有长间隔基的PP（6）TPhCN和PP（6）TPhOMe具有更强的Cotton效应。此外,本文还将甲壳型液晶高分子和共轭聚合物在分子水平上有效结合,首次合成了一种新型以聚噻吩为共轭主链,对苯二甲酸双（对甲氧基苯）酯液晶基元以重心位置直接连接于共轭主链上的新型甲壳型液晶共轭聚合物,对其其结构和性能之间的关系进行了初探。从设计合成单体入手,以FeCl₃为催化剂,CHCl₃为溶剂,得到了该新型聚合物。表征了单体和聚合物的结构,对其结构与性能之间的关系进行了初步探讨。结果表明:该聚合物为无规聚合物,具有良好的热稳定性,且光致发光最大发射峰为550nm。通过偏光显微镜观察,单体为向列相热致型液晶。与主链为柔性链的甲壳型液晶聚合物不同,当主链为刚性的共轭链时,主链与液晶基元之间具有强烈的偶合作用,因而使得聚合物却失去了液晶性能。更多还原

【Abstract】 Combining liquid crystallinity and luminescence into the polymer, liquid crystalline conjugated polymers （LCCP） are currently drawing interest from the viewpoint of multifunctional electrical and optical materials. The introduction of orientable mesogenic moieties onto a conjugated polymer backbone might increase the conjugation in the main chain and the spontaneous orientation and externally forced alignment of the mesogens enable us to control electrical and optical properties and to obtain the materials with excellent properties. The terphenyl is not only a chromophore but also a mesogenic core. Thus, in this paper, terphenyl mesogenic group was introduced onto different conjugated main chain, such as polyacetylene, polythiophene and poly（p-phenylene）, to obtain novel LCCP containing terphenyl mesogenic pendant. The effects of the structural variation on their properties, especially their mesomorphism and photoluminescence behaviors, were studied.Novel acetylene monomers containing cyanoterphenyl groups, namely, 4-[（4’-cyano-4-terphenylyl）oxy]-1-butyl-1-butyne A（bu）TPhCN and 3-[（4’-cyano-4-terphenylyl）oxy]-1-phenyl-1-proyne A（Ph）TPhCN were synthesized. A（bu）TPhCN was polymerized with WCl₆/PhSn₄ catalyst successfully to give the liquid crystalline conjugated disubstituted polyacetylene containing cyanoterphenyl mesogenic pendant PA（bu）TPhCN. Polymerization of monomer A（Ph）TPhCN with phenyl substitute did not obtain any product. The results indicate that the stereoeffect of the bulky cyanoterphenyl group and phenyl seems to inhibit the reaction. The structures and properties of the disubstituted polyacetylene and monomers were characterized and evaluated with nuclear magnetic resonance （¹H NMR）, infrared spectroscopy （FT-IR）, X-ray diffraction （XRD）, differential scanning calorimetry （DSC）, polarized optical microscopy （POM）, ultraviolet spectroscopy （UV）, and photoluminescence （PL）. The monomers show enantiotropic smectic phases in the heating and cooling processes, while the polymer PA（bu）TPhCN exhibits a nematic phase, due the coupling between the mesogen and main chain. The existence of the chromophoric cyanoterphenyl core endows the monomers with strong UV absorption and high photoluminescence, and the polymer PA（bu）TPhCN can emit a strong light of 411 nm.Novel disubstituted propiolates [C₅H₁₁C≡CCOO-terphenyl-R; R=CN, A（COO）TPhCN; R=OCH₃, A（COO）TPhOMe] bearing chromophoric terphenylene mesogenic groups with different terminal groups were synthesized by Suzuki coupling and esterification, where the terphenyl groups were connected to the C≡C through ester linkage directly. The polymerization and properties of the monomers were investigated. Using transition-metal catalysts such as the classical MoCl₅- and WCl₆-based metathesis catalysts, the polymerization of the monomers were carried out in a series of different solution, however, did not obtain any products. It suggests that the WCl₆- and MoCl₅- based catalysts are poisoned by the polar groups, on the other hand, the bulk terphenyl groups and the long alkyl chain around the C≡C bond might inhibit the reaction. The monomer with CN terminal group displays monotropic nematicity, whereas the one with OCH₃ terminal group exhibits enantiotropic nematicity and smecticity （SmA_d） with a bilayer arrangement. Ultraviolet spectroscopy and photoluminescence measurements also show that the terphenyl groups endow disubstituted propiolates with strong UV light absorption and high photoluminescence. The polymers with donor-acceptor pairs luminescent more strongly than those without such push-pull pairs.Series of polythiophenes containing terphenyl mesogenic side chain at the 3rd position with different terminal groups and spacer length {-[Thiopheneyl-CH₂COO-terphenyl-R]_n-; R=CN, PT（0）TPhCN; R=OCH₃, PT（0）TPhOMe; -[Thiopheneyl-CH₂COO-（CH₂）₆-O-terphenyl-CN]_n-, PT（6）TPhCN} were synthesized. The structures and properties of the monomers and polymers were characterized and evaluated. All of the polymers are stable, losing little of their weights when heated to≥300℃. The polymers show good solubility and can be dissolved in common solvents. The monomers all exhibit enantiotropic mesogen phases, while the polymer PT（0）TPhOMe and PT（0）TPhCN with short spacers could not exhibit liquid crystallinty at elevated temperature. With the space length increasing, the PT（6）TPhCN shows enantiotropic SmA_d phase, due to the longer spacer decreases the coupling between mesogen and main chain and favors the better packing arrangements. The existence of the chromophoric terphenyl core endows the polymers with high photoluminescence. Furthermore, push-pull pairs and the longer spacer favor the enabling light emission.Novel liquid crystalline poly（p-phenylene）s bearing cyanoterphenyl mesogenic pendants with varying spacer lengths and terminal groups{-[C₆H₃-COO-terphenyl-CN]_n-, PP（0）TPhCN; -[C₆H₃-COO-（CH₂）₆-O-terphenyl-R]_n-; R=CN, PP（6）TPhCN; R=OCH₃, PP（6）TPhOMe} were designed and synthesized, and the effects of structural variations on the liquid crystallinity behaviors and the optical properties of the polymers were studied. All the monomers and polymers show enantiotropic smectic phases, even including the polymer PP（0）TPhCN with short spacers. Photoexcitation of their solutions induces strong blue light emission. The PL of PP（6）TPhCN is much stronger and red-shifted to the visible spectral region, even extending to 600 nm, than that of PP（0）TPhCN, because the longer spacer may have better segregated the backbone and hence enhances the stronger emission in the photoluminescence. Push-pull pairs also exert influence on the photoluminescence. Another interesting and outstanding property also could be found in this type of polymers. Due to the stric crowding, without introducing any chiral center, terphenyl mesogen pendants orientating around the main chain forces the main chain showing spiral conformation along the main chain in the long region and a short spacer is favorable.Furthermore, we have attempted to synthesis a novel Mesogen-jacketed liquid crystalline conjugated polymer—polythiophene with directly attached bis（4-methoxyphenyl）terephthalate mesogen as pendant at the centrobaric position using FeCl₃ as the catalyst, CHCl₃ as the solvent. The structures and properties of the monomer and polymer were characterized and evaluated. The result indicates that the polymer has the expected structure, and the polymer is a random polymer with high thermal stability. Upon photoexcitation, the polymer can emit strong yellow light at 550nm. Different from the Mesogen-jacketed liquid crystalline polymers with flexible main chain, due to the strong interaction between the mesogen side chain and backbone, the polymer with rigid backone could not show any optical anisotropy, although its monomer possesses nematic phase.更多还原