Metal Alkoxide Catalyst for Controlled Polyester Molecular Weight
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Solution Overview
Problem
Current methods for synthesizing polyesters like poly-ε-caprolactone and polylactide face challenges in controlling molecular weight and distribution, leading to poor mechanical properties and low molecular weight polymers, especially with catalysts such as stannous octate and Schiff base aluminum, which result in wide molecular weight distributions and low catalytic activity.
Innovation Solution
A metal alkoxide complex with a specific molecular formula [Xn-mM(OCR1R2R3)m].y.(organic solvent)z is developed, where M is a main group or transition metal, and used in combination with a hydroxy-containing compound to catalyze the polymerization of ε-caprolactone or lactide monomers, allowing for controlled molecular weight and narrow distribution of the resulting polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If stannous octoate is used as catalyst, then polymerization can proceed, but molecular weight cannot be controlled and distribution is wide
Solution Approach 1:
The patent changes the chemical parameters of the catalyst system by using metal alkoxides with specific metal elements (Mg, Ca, Sr, Ba, Al, Zn) instead of stannous octoate. This parameter change enables precise control of molecular weight while maintaining narrow molecular weight distribution, directly resolving the contradiction between manufacturability and reliability of the polymerization process.
2Productivity
If Schiff base aluminum catalyst is used, then polymerization can occur, but catalytic activity is low and molecular weight is relatively low
Solution Approach 1:
The patent changes the catalyst composition parameter by selecting from a broader range of metal elements (main group and transition metals) with varying valence states. This enables achieving both high catalytic activity and high molecular weight polymers, resolving the contradiction between productivity and quantity of substance.
3Quantity of substance
If direct dehydration polycondensation is used, then synthesis can proceed, but molecular weight is low and properties are insufficient
Solution Approach 1:
The patent substitutes the direct dehydration polycondensation method with ring-opening polymerization using metal alkoxide catalysts. This methodological substitution eliminates water production, enables higher molecular weight synthesis, and achieves superior mechanical properties, resolving the contradiction between quantity of substance and reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The metal alkoxide complex exhibits high catalytic activity, enabling the production of polymers with adjustable molecular weights ranging from 1000 to 600,000 and a narrow molecular weight distribution of 1.03 to 1.50, achieving 'immortal' polymerization and improved mechanical properties.
Implementation Method 1
the metal alkoxide complex and the catalyst composition thereof have high catalytic activity, and can be used for catalyzing the polymerization of ε-caprolactone monomer or lactide monomer
Data Source
AI summary
The invention provides a metal alkoxide complex of Formula (I), wherein X, M, R1, R2, R3, m, n, y and z are as defined in the Description. The invention also provides a catalyst composition comprising the metal alkoxide complex and a hydroxy-containing compound, wherein the molar ratio of the metal alkoxide complex to the hydroxy-containing compound is 1:0.1-1000. The invention also provides a production method of poly-ε-caprolactone or polyactide, wherein an ε-caprolactone monomer or a lactide monomer is reacted in the presence of the metal alkoxide complex or catalyst composition to obtain poly-ε-caprolactone or polylactide. The metal alkoxide complex and the catalyst composition thereof can be used to catalyze the synthesis of poly-ε-caprolactone or polylactide with a high efficiency. The molecular weight of polycaprolactone or polylactide can be controlled by the molar ratio of the metal alkoxide complex and the hydroxy-containing compound, and is adjustable in the range of 1000-600,000, and wherein the molecular weight distribution is from 1.03 to 1.50.[Xn-mM(OCR1R2R3)m]y.(organic solvent)z (I)