阅读说明：本技术 一种可逆加成-断裂链转移聚合体系及其在制备嵌段环化共聚物中的应用 (Reversible addition-fragmentation chain transfer polymerization system and application thereof in preparation of block cyclic copolymer ) 是由 来国桥 胡自强 李文清 于 2019-10-10 设计创作，主要内容包括：本发明涉及一种可逆加成-断裂链转移聚合体系及其在制备嵌段环化共聚物中的应用,由聚合介质、双官能团单体、单官能团单体、链转移试剂、引发剂构成的聚合体系本发明通过碳或硅上的偕二甲基效应,设计双官能团呈相互接近构象的单体分子,通过可逆加成-断裂链转移聚合体系,引发双官能团单体及单官能团环化共聚得到主链上序列具有有序结构的新型嵌段环化共聚物。本发明方法所设计的单体合成简便,克服了因发生交联反应而不能得到目标产物的困难,通过本方法容易合成具有不同大小环的线性环化共聚物。(The invention relates to a reversible addition-fragmentation chain transfer polymerization system and application thereof in preparing block cyclic copolymers. The monomer designed by the method of the invention is simple and convenient to synthesize, overcomes the difficulty that the target product cannot be obtained due to the occurrence of a cross-linking reaction, and can easily synthesize linear cyclized copolymers with rings of different sizes.)

1. A reversible addition-fragmentation chain transfer polymerization system is characterized in that the polymerization system is composed of a polymerization medium, a bifunctional monomer, a monofunctional monomer, a chain transfer reagent and an initiator,

the structural formula of the bifunctional monomer is shown as (I):

in the formula (I), the compound is shown in the specification,y is carbon or silicon, R₁Is methyl, phenyl or isopropyl; r₂Is methyl, phenyl or isopropyl; r₃Is hydrogen or methyl, n is 2, 3 or 4;

the structural formula of the monofunctional monomer is shown as (II):

r in the formula (II)₄Is methyl or ethyl, R₅Is a hydrogen atom or a methyl group.

2. The reversible addition-fragmentation chain transfer polymerization system of claim 1, wherein: the polymerization medium is one of dimethyl sulfoxide, N-dimethylformamide and toluene.

3. The reversible addition-fragmentation chain transfer polymerization system of claim 1, wherein: the chain transfer reagent is dithiobenzoic acid cyano isopropyl ester.

4. The reversible addition-fragmentation chain transfer polymerization system of claim 1, wherein: the initiator is azobisisobutyronitrile.

5. The reversible addition-fragmentation chain transfer polymerization system of claim 1, wherein: the mole ratio of the bifunctional monomer to the monofunctional monomer to the chain transfer agent to the initiator is 100: 100: 4: 1.

6. the reversible addition-fragmentation chain transfer polymerization system of claim 1, wherein: the concentration of the bifunctional monomer or the monofunctional monomer in the polymerization system is 0.0375 mol/L-0.075 mol/L.

7. Use of a reversible addition-fragmentation chain transfer polymer system as claimed in claim 1 in the preparation of a block copolymer cyclized by the steps of:

(1) under the protection of nitrogen, adding a chain transfer reagent into a polymerization medium, and stirring for dissolving;

(2) adding a bifunctional monomer and a monofunctional monomer which are used for introducing nitrogen and removing oxygen, and continuously introducing nitrogen and removing oxygen;

(3) adding an initiator under the protection of nitrogen, heating to a set temperature, and reacting at a constant temperature;

(4) after the reaction, the polymerization solution was precipitated with methanol to obtain a copolymer.

8. Use of a reversible addition-fragmentation chain transfer polymer system according to claim 7 in the preparation of a block copolymer cyclized: the reaction temperature of the polymerization system is 75-90 ℃.

9. Use of a reversible addition-fragmentation chain transfer polymer system according to claim 7 in the preparation of a block copolymer cyclized: the polymerization medium is one of dimethyl sulfoxide, N-dimethylformamide and toluene; the chain transfer reagent is dithiobenzoic acid cyano isopropyl ester; the initiator is azobisisobutyronitrile.

10. Use of a reversible addition-fragmentation chain transfer polymer system according to claim 7 in the preparation of a block copolymer cyclized: the mole ratio of the bifunctional monomer to the monofunctional monomer to the chain transfer agent to the initiator is 100: 100: 4: 1; the concentration of the bifunctional monomer or the monofunctional monomer in the polymerization system is 0.0375 mol/L-0.075 mol/L.

Technical Field

The application belongs to the technical field of high molecular compounds, and particularly relates to a reversible addition-fragmentation chain transfer polymerization (RAFT) system and application thereof in preparation of a block cyclic copolymer.

Background

Linear cyclopolymers (Linear cyclopolymers) whose backbone contains macrocycles [ Sakai, r.; satoh, t.; kakuchi, r.; kaga, h.; kakuchi, t. macromolecules 2004,37,3996] is a new class of polymers obtained by alternating intramolecular/intermolecular chain growth through bifunctional monomers. The macrocyclic ring in the polymer can be designed to be used as a recognition main body of metal ions, organic small molecules, chiral molecules (such as amino acid) and the like, so that the polymer is expected to be used as a stationary phase separation material for metal ion separation, chiral separation and the like. Cyclopolymerization (Cyclopolymerization) is a polymerization reaction in which two chain transfer reactions, i.e., intramolecular cyclization and intermolecular reaction, are alternately performed by initiating two reactive functional groups in a monomer molecule, and Cyclopolymerization is a main method for synthesizing linear cyclopolymerized polymers. Examples of the cyclopolymerization include radical polymerization, anion polymerization, transition metal-catalyzed polymerization, Group Transfer Polymerization (GTP), Atom Transfer Radical Polymerization (ATRP), and the like. Due to the influence of the thermodynamic stability of the cyclization reaction, the successfully synthesized cyclized polymer is mainly a linear cyclized polymer containing five-membered rings and six-membered rings [ Coluccini, C.; metrangolo, p.; parachini, M.; pasini, d.; resnat, G.; righetti, P.J.Polym.Sci.part A: Polym chem.2008,46,5202], synthesis of macrocyclic linear cyclic polymers is difficult.

The key point for effectively synthesizing the macrocyclic linear cyclized polymer is that reaction functional groups of designed bifunctional monomer molecules are in a mutually close conformation, and the conformation is favorable for reducing the activation energy of intramolecular cyclization reaction and improving the intramolecular cyclization reaction activity. By utilizing the tension of a cyclohexane ring and the action of hydrogen bonds of adjacent amino groups in molecules, Endo designs monomer molecules with bifunctional groups in a mutually close conformation for the first time and successfully synthesizes a linear cyclized polymer containing a nineteen-membered macrocyclic ring [ Ochiai, B.; otoani, y.; endo, t.j.am.chem.soc.2008,130,10832 ]. Due to limitations in monomer design methods, there are fewer examples for synthesizing macrocyclic linear cyclic polymers.

The invention hopes to design the macrocyclic cyclopolymerization monomer by utilizing the gem-dimethyl (Thorpe-Ingold) effect, overcomes the difficult problem of difficult synthesis of the macrocyclic cyclopolymerization polymer caused by relatively low activity of double functional groups in monomer molecules by utilizing the designed monomer, and synthesizes a novel block cyclopolymerization copolymer by cyclopolymerization.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention utilizes a brand-new cyclized monomer design method, namely, the cyclized polymerization monomers with the reaction bifunctional groups in a mutually close conformation are designed through a gem-dimethyl effect on carbon or silicon, the reaction activity of the reaction bifunctional groups of the monomers is improved through the design, and then the RAFT technology is utilized to synthesize the novel block cyclized copolymer.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a reversible addition-fragmentation chain transfer polymerization system is a polymerization system composed of a polymerization medium, a bifunctional monomer, a monofunctional monomer, a chain transfer reagent and an initiator,

the structural formula of the bifunctional monomer is shown as (I):

in the formula (I), Y is carbon or silicon, R₁Is methyl, phenyl or isopropyl; r₂Is methyl, phenyl or isopropyl; r₃Is hydrogen or methyl, n is 2, 3 or 4;

the structural formula of the monofunctional monomer is shown as (II):

r in the formula (II)₄Is methyl or ethyl, R₅Is a hydrogen atom or a methyl group.

The invention initiates bifunctional monomers and monofunctional group cyclopolymerization through a reversible addition-fragmentation chain transfer polymerization system to obtain a novel block cyclopolymerization copolymer with a main chain sequence having an ordered structure. The general formula of the reversible addition-fragmentation chain transfer polymerization system is S/M1/M2/R/I, wherein S represents a polymerization medium, M1 is a bifunctional monomer, M2 is a monofunctional monomer, R is a chain transfer reagent, and I is an initiator.

Preferably, the polymerization medium is one of dimethyl sulfoxide, N-dimethylformamide and toluene.

Preferably, the chain transfer agent is cyanoisopropyl dithiobenzoate (CPDB).

Preferably, the initiator is Azobisisobutyronitrile (AIBN).

Preferably, the molar ratio of the bifunctional monomer, the monofunctional monomer, the chain transfer agent and the initiator is 100: 100: 4: 1.

preferably, the concentration of the bifunctional monomer or the monofunctional monomer in the polymerization system is from 0.0375mol/L to 0.075 mol/L. The present invention configures the concentrations of M1 and M2 by controlling the addition amount of the polymerization medium (solvent), the control of the concentrations being an important factor in the preparation of block cyclized copolymers of ordered structure.

The use of the above reversible addition-fragmentation chain transfer polymer system in the preparation of a block copolymer comprising the steps of:

(1) under the protection of nitrogen, adding a chain transfer reagent into a polymerization medium, and stirring for dissolving;

(2) adding a bifunctional monomer and a monofunctional monomer which are used for introducing nitrogen and removing oxygen, and continuously introducing nitrogen and removing oxygen;

(3) adding an initiator under the protection of nitrogen, heating to a set temperature, and reacting at a constant temperature;

(4) after the reaction, the polymerization solution was precipitated with methanol to obtain a copolymer.

Preferably, the reaction temperature of the polymerization system is 75 to 90 ℃.

Preferably, the polymerization medium is one of dimethyl sulfoxide, N-dimethylformamide and toluene; the chain transfer reagent is dithiobenzoic acid cyano isopropyl ester; the initiator is azobisisobutyronitrile.

Preferably, the molar ratio of the bifunctional monomer, the monofunctional monomer, the chain transfer agent and the initiator is 100: 100: 4: 1; the concentration of the bifunctional monomer or the monofunctional monomer in the polymerization system is 0.0375 mol/L-0.075 mol/L.

The double functional groups in the designed polymeric monomer are in mutually close conformations, the conformations improve the activity of intramolecular cyclization reaction, the reaction is favorably carried out according to the direction of generating macrocyclic linear cyclization polymers, and the difficulty that target products cannot be obtained due to the occurrence of crosslinking reaction is overcome.

Compared with the prior art, the monomer designed by the method is simple and convenient to synthesize, and the linear cyclized copolymer with rings of different sizes can be easily synthesized by the method.

Detailed Description

The technical solutions of the present invention are further specifically described below by examples, which are for illustration of the present invention and are not intended to limit the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. The parts of materials in the examples are all parts by mole.