CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 of international application of PCT application serial no. PCT/CN2018/074317, filed on Jan. 26, 2018, which claims the priority benefit of China application no. 201711188236.2, filed on Nov. 24, 2017. The entirety of each of the above mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

The present disclosure belongs to the field of organic polymer semiconductor materials preparation and relates to an organic nanogrids, nanopolymers thereof and preparation methods therefor.

Description of Related Art

The connection mode of nano-scale molecular blocks is the core of building complex topological polymers. Efficient nano-connection needs to meet the following standards: (1) The ring-forming structure is singular during the chemical bond connection process; (2) The random cross-linking process is inhibited as much as possible. Among them, non-covalent bonds and reversible covalent bonds are current two major nano-connection modes. The characteristics of such connections are: the bond energy is relatively small (10˜300 KJ/mol) (J. Am. Chem. Soc. 2016, 138, 3255), and a dynamic reversible process can be formed in the process of bond-forming and bond-breaking. This can help generate a corrective effect when dislocated cross-linking occurs, thereby forming an orderly structured nano-block, such as covalent/super molecular organic framework (Science, 2017, 355, 1585). However, this type of dynamically reversible nano-connection is only suitable for situations where the bond energy is small (such as multiple hydrogen bonds, B—O bonds, etc.) (Science, 2005, 310, 1166; Science, 2007, 316, 210.) and a few obviously dynamically reversible organic reactions (the commonly seen one is the nucleophilic addition reaction of aldehydes) (J. Am. Chem. Soc. 2017, 139, 2421). In contrast, for most C—C bond coupling reactions, it is difficult to establish an effective dynamic balance because it takes a lot of energy (at least 350 KJ/mol) to break a C—C bond. In this case, once a dislocated connection occurs, it is difficult to correct and restore it, so it will eventually lead to the generation of random cross-linked polymers. In addition, this type of dynamic reversible reaction is controlled by the thermodynamic process, requiring a long reaction time (at least three days) and harsh reaction conditions. This is not conducive to the mass production of nanopolymers. Therefore, it is very difficult to explore efficient nano-connection based on C—C bonds to construct nanopolymers with a robust structure.

In fact, in addition to the thermodynamically reversible covalent bond strategy, other strategies, such as using non-covalent bonds to assist in inducing the formation of covalent bonds with the help of kinetic control, can also possibly minimize the disorderly cross-linking among molecules and make the bonding structure singular so as to achieve the requirement of the efficient nano-connection. But this also needs a corresponding conformational structure.

SUMMARY

In view of this, the present disclosure provides an organic nanogrids, nanopolymers thereof and preparation methods therefor in the context of efficient nano-connection. Compared with other organic closed-loop structures, the structural skeleton of the organic nanogrid is similar to a parallelogram, as shown inFIG. 1, wherein a pair of vertices have extensible and expandable properties. It can form a rigid polymer with regular structure through certain polymerization reaction. The method of synthesizing an organic nanogrid is to start from a precursor with appropriate geometric configuration, such as fluorene-like tertiary alcohol, and then to make the precursor undergo Friedel-Crafts cyclization reaction (as the basic model of nano-connection). This synthesis method has a high yield and few product types which are easy to separate. So it has important application prospects and good commercial development potential. On the other hand, this nano-connection can be used as a key way for constructing one-dimensional rigid organic nanopolymers. This connection mode can overcome shortcomings, such as the low molecular weight of the polymer, caused by the negative influence of steric hindrance in the traditional Suzuki or Yamamoto polymerization reaction. At the same time, it has a lot of advantages, such as transition metal-free catalysis, mild conditions, environmental friendliness and atomic economy, and is suitable for mass production of organic nanopolymers. On this basis, the present disclosure designs A2B2monomers and can flexibly prepare one-dimensional nanopolymers with the help of nano-connection, thus laying a foundation for developing polymers with complex topologies.

The technical scheme of the present disclosure is as follows:

An organic nanogrid, with a general formula (I), is a centrally symmetric rigid closed-loop structure composed of two fluorene-like groups, of which one fluorene-like group belongs to a 9-phenyl fluorene derivative and can extend out to two connection sites, and the other fluorene group has a carbazole-like geometry;



Wherein, R1includes: 1) linear chain type: hydrogen atom, alkane chain, alkoxy chain, and alkyl chain with halogen atoms introduced at the end; 2) branched chain type: tert-butyl group, and branched alkyl chain with oxygen atoms; n is a natural number from 1 to 10. Their specific structures are as follows:



R2is a halogen or a photoelectrically active group. The above-mentioned photoelectrically active group includes: phenyl, pyrene, fluorene, nitrobenzene, benzocyano, and ethylcarbazole. Their specific structures are as follows:



X can be N atom, O atom or S atom, where the following structures can be introduced on N atoms:


is one of the following structures:


is one of the following structures:



A nanopolymer, with a general formula (II), is a polymer synthesized from some of the above-mentioned organic nanogrids through homopolymerization or copolymerization with photoelectric groups;



Wherein, n is a natural number from 1 to 10;


is one of the following structures:



A method for preparing the organic nanogrid: a fluorene-like tertiary alcohol undergoes the Friedel-Crafts reaction in the presence of acid catalyst, and the fluorene-like tertiary alcohol undergoes intermolecular dehydration and cyclization to form the corresponding organic corner-cut grid. The reaction route is reaction formula (III).



A method for preparing the nanopolymer: the corresponding organic nanopolymer is obtained from brominated organic nanogrids through the C—C bond coupling reaction. The reaction route is reaction formula (IV).



A method for preparing the nanopolymer: the organic nanopolymer is obtained from A2B2polymerization monomers directly through the Friedel-Crafts polymerization. The reaction route is reaction formula (V).



The present disclosure discloses an organic nanogrids, nanopolymers thereof and preparation methods therefor. It focuses on developing an efficient nano-connection mode, which has the following advantages compared with other nano-block/polymer connection modes:

(1) It inhibits the occurrence of cross-linked structures generated by disordered bonds by means of supramolecular assistance;

(2) It adopts the kinetically controlled supramolecular assistance mode to overcome the long time and harsh reaction conditions required by the traditional dynamic reversible process, so it can easily achieve industrial mass production;

(3) It overcomes shortcomings, such as the low molecular weight of the polymer, caused by the influence of steric hindrance in the traditional Suzuki or Yamamoto coupling polymerization reaction, so it facilitates the preparation of nanopolymers with a high molecular weight.

