Studies on Multifunctional Block Copolymers for Holography

采用原子转移自由基聚合（ATRP）方法，先将丙烯酸酯与氰基苯（GB）单元聚合，再将丙烯酸酯与咔唑（Cz）单元聚合，合成了由光导和电光活性嵌段组成的新型光折变嵌段共聚物。在嵌段共聚物的DSC热图中，第一次运行时观察到两个玻璃化转变温度对应于两个嵌段的温度，表明两个嵌段相互微相分离。通过四波混频（FWM）实验，发现在80 V/μm下，聚合物的衍射效率提高了25%。该值远高于具有相似化学成分的统计共聚物。在双光束耦合（2BC）实验中，在45 V/μm下观察到非对称的能量交换（增益系数为100 cm^<-1>）。合成了一种新型不对称丁二酸盐（TH-NVA），它含有供电子的4-（2-硝基乙烯基）苯胺衍生物。发现当液体样品在室温下在空气中冷却时，TH-NVA很容易形成非晶玻璃。差示扫描量热法测得结晶样品的熔点为130℃，玻璃化样品的玻璃化转变温度为44℃。在较长波长区域的吸收尾是由电子接收单元和电子提供单元之间的电荷转移相互作用引起的。在两个束流耦合实验中，TH-NVA在没有外加电场的情况下表现出不对称的能量传递（耦合增益42cm^<-1>）。

Novel photorefractive (PR) block copolymers consisting of photoconductive and electro-optically(EO) active blocks were synthesized via the atom transfer radical polymerization (ATRP) of acrylates with cyanobiphenyl (GB) unit followed by the polymerization of acrylate with carbazole(Cz) moiety. In DSC thermogram for block copolymer, two glass transition temperatures corresponding to those for both blocks were observed on the first run indicating that both blocks were microphase separated each other. By four-wave mixing (FWM) experiments for the polymers doped with electron accepting compounds, 25% of diffraction efficiency was observed at 80 V/μm. This value was much higher than that observed in statistical copolymer with the similar chemical composition. In two-beam coupling (2BC) experiments, rnmetri c energy exchange (gain coefficient of 100 cm^<-1>) was observed at 45 V/μm. Novel asymmetric succinate (TH-NVA) containing electron accepting thioxanthone and electron donating 4-(2-nitrovinyl)aniline derivative was synthesized. TH-NVA was found to readily form an amorphous glass when the liquid sample was cooled in air at room temperature. Differential scanning calorimetry revealed that the melting point of crystalline sample and the glass transition temperature of glassy sample are 130 and 44℃, respectively. Absorption tail in longer wavelength region was due to the charge transfer interaction between electron accepting and donating units. In two beam coupling experiments, TH-NVA showed asymmetric energy transfer (coupling gain ; 42cm^<-1>) without an external electric field.