Programming Liquid Crystalline Elastomer Networks with Dynamic Covalent Bonds

A liquid crystalline elastomer (LCE) network consisting of dynamic covalent bonds (DCBs) is referred as a LCE vitrimer. The mesogen alignment and the network topology can be reprogrammed locally in the LCE vitrimer by activating the bond exchange reactions using an external stimulus. After removal of the external stress, a new network is formed and the reprogrammed shape can be fixed, leading to a different set of the physical properties of the LCE vitrimers. Herein, this type of emerging materials is reviewed by a brief introduction of the fundamentals of LCEs, followed by discussions of various DCBs and the design principles for LCE vitrimers. After a presentation of different strategies to improve the stability and reprogrammability of the registered mesogen alignment, approaches to prepare LCE vitrimers with complex shapes and their actuations are discussed. Potential applications such as self-healing and recycling, mechanochromic effects, and post-functionalization of nanopores are also reviewed, followed by the conclusion of the remaining challenges and opportunities.     

茶菌人工复合菌剂构建和发酵性能分析

利用从茶菌中分离纯化的4个优势菌株构建人工复合菌剂。通过单独培养和不同复合方式培养的比较，确定菌株在茶菌发酵和菌膜形成中的作用；采用高效液相色谱、顶空固相微萃取和气相色谱-质谱联用等方法分析茶菌发酵过程中主要生化成分变化；经历多次传代接种后，采用人工分离和宏基因组分析相结合分析菌群组成和稳定性。结果表明：供试的4个菌株中，葡糖醋杆菌J5(Gluconacetobacter sp. J5)是产生纤维素和菌膜的核心菌株。混合菌株组合C3C5C6J5发酵后在菌体生长、糖利用、发酵液pH值、总酸度和茶多酚含量等指标与自然发酵相似。经历6代转接后菌群稳定，复配的菌株在人工菌群中均为优势菌株。表明从天然茶菌饮料中分离纯化功能菌株，通过菌株复配构建稳定的人工发酵剂可行，为茶菌的标准化工业生产打下基础。