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For the first time, the Chinese Academy of Sciences uses electrochemically initiated solid phase iterative polymerization

2019-07-08 来源:亚科官网
 
The function and properties of polymers are closely related to their own chemical structure, such as their chemical structure, composition, configuration and monomer sequence structure. In principle, even if the same monomer composition has a different sequence structure, it is possible to tailor the properties of the material. Polymerization methods for synthetic sequence controllable polymers are currently reported, most of which are not yet known as sequence-specific polymerizations.
Merrifield solid phase iterative synthesis is a strategy that can accurately prepare precise sequence controllable polymers. It is the most suitable method for synthesizing sequence-controlled and well-defined macromolecules. However, solid phase iterative synthesis is difficult to monitor in real time as the chain grows. On the other hand, the solid phase support greatly limits the reaction rate of the coupling reaction, which ultimately leads to a significant decrease in reaction yield and sequence precision. Unstable covalent bond reactions during polymerization typically require protection and deprotection reaction steps. This method is currently unable to synthesize complex macromolecular structures, and the synthesis of photo-functionalized polymers has not been reported.
In the process of electrochemical synthesis of polymers, electrochemical oxidation and electrochemical reduction reactions are generally used for electrochemical synthesis of polymers, respectively. When the electrochemical oxidation reaction or the reduction reaction is carried out, at least two reaction sites are simultaneously excited, and the molecular weight distribution and the sequence structure of the polymer are uncontrollable.
The Li Mao Group of the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, for the first time, simultaneously utilized electrochemical oxidation and reduction reactions. Based on self-assembled electroactive single molecules on the electrodes, a single reaction monomer was controlled by simply controlling the positive and negative bias voltages. Solid phase iterative stepwise polymerization. Due to the dependence of the oxidized strength of the 3,6-position of carbazole, the topology of this polymerization is also controllable. In principle, this polymerization allows for the sequence-controlled polymerization of reactive monomers of different metal complexes. Compared with the classical solid phase iterative synthesis method, this polymerization method has high reaction rate and efficiency, does not require the protection and deprotection steps of the reactive group, and can monitor the progress of the polymerization reaction by ultraviolet visible absorption spectroscopy and electrochemistry.
By this method, effective combination and functional deepening of different photoelectric functional units in a single-chain polymer can be achieved. This single-molecule electrochemically controlled polymerization not only controls the thickness of the ultra-thin film (<20 nm) on a molecular scale, but also facilitates the electrochemical preparation of large-area thin films, and has the potential for automated synthesis.