CN-121824923-B - Preparation method of cyclic poly (delta-valerolactone)

Abstract

The invention discloses a preparation method of cyclic poly (delta-valerolactone), which takes delta-valerolactone as a monomer, and diethylene glycol amino bridge Lian Shuangfang oxo aluminum complex with definite structure, simple synthesis and high catalytic efficiency as a catalyst, and the cyclic poly (delta-valerolactone) is obtained through ring-opening polymerization reaction. The catalyst adopted by the invention provides a high-efficiency and easy-to-realize catalytic system for the controllable preparation of the cyclic poly (delta-valerolactone), greatly reduces the operation difficulty and cost of the preparation process, prepares the pure cyclic topological structure poly (delta-valerolactone) with high molecular weight and narrow molecular weight distribution, generates wireless polymer impurities, does not need the subsequent complicated separation and purification steps, simplifies the preparation process, further improves the preparation efficiency and reduces the preparation cost.

Inventors

• YAO YINGMING
• LIAO LIMEI

Assignees

• 苏州大学

Dates

Publication Date

20260508

Application Date

20260313

Claims (8)

1. 1. A method for preparing cyclic poly (delta-valerolactone), comprising the steps of: Under the protection of inert gas, dissolving delta-valerolactone and diethylene glycol amino bridge Lian Shuangfang oxyaluminum complex in an organic solvent, and carrying out ring-opening polymerization reaction at 30-80 ℃ to obtain cyclic poly (delta-valerolactone), wherein the molar ratio of delta-valerolactone to diethylene glycol amino bridge Lian Shuangfang oxyaluminum complex is (100-1000): 1, and the organic solvent is one or more selected from toluene, chlorobenzene, fluorobenzene, bromobenzene, n-hexane and tetrahydrofuran; the structural formula of the diethylene glycol amino bridge Lian Shuangfang oxyaluminum complex is Wherein each R 1 、R 2 is independently selected from one of tert-butyl, methyl, cumyl and chlorine; the structural formula of the cyclic poly (delta-valerolactone) is Wherein n is 122-3020.
2. 2. The method according to claim 1, wherein the inert gas is nitrogen or argon.
3. 3. The preparation method according to claim 1, wherein delta-valerolactone and diethylene glycol amino bridge Lian Shuangfang aluminum oxide complex are dissolved in an organic solvent to obtain a mixed solution, and the concentration of delta-valerolactone in the mixed solution is 2.0-5.4 mol/L.
4. 4. The method according to claim 1, wherein the ring-opening polymerization reaction temperature is 30 to 50 ℃.
5. 5. The method according to claim 1, wherein the ring-opening polymerization reaction time is 25 min to 12 h.
6. 6. The method according to claim 1, wherein the method further comprises the steps of settling, filtering and drying the reaction product after the ring-opening polymerization reaction is completed.
7. 7. The process of claim 6, wherein the reaction product is precipitated by adding n-hexane.
8. 8. The method of claim 1, wherein the cyclic poly (delta-valerolactone) has a molecular weight distribution index of 1.11 to 1.35.

Description

Preparation method of cyclic poly (delta-valerolactone) Technical Field The invention relates to the technical field of polymer preparation, in particular to a preparation method of cyclic poly (delta-valerolactone). Background The cyclic polymer has different physical and chemical properties compared with the linear polymer due to the unique topological structure without the terminal group, and particularly comprises smaller hydrodynamic radius, lower intrinsic viscosity, higher thermal stability, higher glass transition temperature (T g) and higher melting point (T m), and the characteristics lead the cyclic polymer to have wide application prospect in the fields of biological medicine, functional materials and the like and become a research hotspot in the fields of high polymer chemistry and supermolecule chemistry. Aliphatic polyester is used as one of the substitutes of non-renewable or difficult-to-degrade plastics, and has important environmental and application values. The poly (delta-valerolactone) has rich raw material sources, simple chemical structure, hydrolyzability, biodegradability, good processability, flexibility and biocompatibility, and has outstanding application potential in the biomedical fields such as drug release systems, tissue engineering scaffolds and the like. At present, the synthesis of cyclic poly (delta-valerolactone) mainly depends on two technical paths of a closed-loop method and a ring expansion method. The ring closure method needs to utilize the active functional group at the tail end of the polymer chain to realize intramolecular cyclization, but linear impurities are easy to generate along with intermolecular side reaction in the reaction process, and the ring closure method needs to be carried out under a highly diluted condition, so that the cyclization efficiency is obviously reduced along with the increase of the molecular weight of the target polymer, and the subsequent separation and purification process is complicated. Although the ring-expanding method is the main stream research direction in recent years, the prior art has obvious limitations that the Eugene Y-X. Chen subject group in 2023 adopts metal complexes such as yttrium, lanthanum, zinc and the like to catalyze delta-valerolactone to carry out ring-opening polymerization, the product is a mixture of cyclic and linear polymers when no alcohol is used for initiation, the pure linear product is obtained by adding an alcohol initiator, the product is the same mixture of linear and cyclic by using molybdenum complex as a catalyst in 2024 CARL REDSHAW and the like, the molecular weight distribution is wider, and the 2025 Haian Xia subject group adopts a bi-component catalytic system composed of trichlorophenylurea and organic base, and the product mainly comprising the cyclic polymer can be obtained under the condition of no initiator, but the generation of linear impurities can not be completely avoided. Essentially, the generation of cyclic poly (delta-valerolactone) depends on molecular lactone exchange reaction, and the reaction process is easy to be accompanied with the generation of linear polymers, and the transesterification reaction rate is difficult to accurately regulate, so that the preparation targets of pure cyclic topological structure, high molecular weight and narrow molecular weight distribution are difficult to be simultaneously realized in the prior art. Therefore, a preparation method of pure cyclic poly (delta-valerolactone) with high activity, mild reaction conditions, high molecular weight and narrow molecular weight distribution is developed, and the preparation method has important technical value and application prospect. Disclosure of Invention The invention aims to solve the technical problems and provide a preparation method of cyclic poly (delta-valerolactone), which adopts diethylene glycol amino bridge Lian Shuangfang oxyaluminum complex as a catalyst, utilizes the structural specificity of the catalyst to realize the regulation and control of ring-opening polymerization reaction, has mild reaction conditions and excellent controllability, can efficiently prepare pure cyclic poly (delta-valerolactone) without linear impurities, and the obtained product has the characteristics of high molecular weight and narrow molecular weight distribution, and does not need complicated subsequent separation and purification steps. The above object of the present invention is achieved by the following technical solutions: a method of preparing a cyclic poly (delta-valerolactone), comprising the steps of: under the protection of inert gas, dissolving delta-valerolactone and diethylene glycol amino bridge Lian Shuangfang oxyaluminum complex in an organic solvent, and carrying out ring-opening polymerization reaction at 30-80 ℃ to obtain the cyclic poly (delta-valerolactone); the structural formula of the diethylene glycol amino bridge Lian Shuangfang oxyaluminum complex is Wherein each R 1、