光/温度双响应三嵌段共聚物的合成及溶液自组装行为

以双官能团聚乙二醇(Br-PEO-Br)为引发剂, 利用原子转移自由基聚合(ATRP)制得了含偶氮苯(AZO)和N-异丙基丙烯酰胺(NIPAM)的两亲性三嵌段共聚物P(AZO₉-co-NIPAM₉)-b-PEO₄₈-b-P(AZO₉-co-NIPAM₉), 并通过核磁共振(¹H NMR)和凝胶渗透色谱(GPC)对产物进行了表征. 该共聚物能够在溶液中自组装形成纳米胶束, 运用透射电子显微镜(TEM)、荧光探针技术和动态光散射(DLS)研究了胶束的形貌、粒径及其在光或温度刺激下的响应行为. 结果表明, 该三嵌段共聚物胶束显现出我们以往报道的二嵌段共聚物所不具有的光释放行为: 包覆有尼罗红的胶束在多次紫外-可见光循环照射之后, 荧光强度和初始状态相比下降了大约40%, 说明尼罗红在此过程中逐渐被释放. 胶束的尺寸随着温度的升高而逐渐缩小.     

氧化锌负载四(4-硝基苯基)钴卟啉催化氧化环己烷性能

将四(4-硝基苯基)钴卟啉(Co-TNPP)负载在氧化锌(Zn O)载体制备负载型金属卟啉催化剂Co-TNPP/Zn O,并对其进行了紫外-可见漫反射光谱(UV-vis),红外光谱(FT-IR),X射线衍射(XRD),热重分析(TG/DTG),比表面分析(BET)和电感耦合等离子体(ICP)表征.考察了催化剂在无溶剂的条件下催化氧气氧化环己烷的性能.实验结果表明:在反应温度为150℃,氧气压力为1.2 MPa,反应时间为2.0 h的条件下,环己烷转化率9.82%,环己醇和环己酮选择性83.37%.负载型金属卟啉催化剂经过5次循环使用,环己烷的平均转化率和环己醇、环己酮平均选择性分别为9.95%、83.61%,催化剂的平均转化数为2.18×105.负载型金属卟啉催化剂Co-TNPP/Zn O在较温和的条件下表现出优良的环己烷催化氧化性能,克服了金属卟啉催化剂难以回收、无法循环使用的缺点,具有很好的工业价值和应用前景.     

Designing high k dielectric films with LiPON—Al2O3 hybrid structure by atomic layer deposition

A large amount of ultra-low-power consumption electronic devices are urgently needed in the new era of the internet of things, which demand relatively low frequency response. Here, atomic layer deposition has been utilized to fabricate the ion polarization dielectric of the LiPON-Al₂O₃ hybrid structure. The LiPON thin film is periodically stacked in the Al₂O₃ matrix. This hybrid structure presents a frequency-dependent dielectric constant, of which k is significantly higher than the aluminum oxide matrix from 1 kHz to 200 kHz in frequency. The increased dielectric constant is attributed to the lithium ions shifting locally upon the applied electrical field, which shows an additional polarization to the Al₂O₃ matrix. This work provides a new strategy with promising potential to engineers for the dielectric constant of the gate oxide and sheds light on the application of electrolyte/dielectric hybrid structure in a variety of devices from capacitors to transistors.