Low Molecular Weight Poly(alkylene carbonate) via Chain Transfer Agent
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Solution Overview
Problem
Current methods for preparing poly(alkylene carbonate) via copolymerization of carbon dioxide and epoxide result in high-molecular-weight polymers with insufficient mechanical strength and limited applications due to low glass transition temperature, and existing low-molecular-weight polymers require large amounts of catalysts, making them economically inefficient.
Innovation Solution
A method involving the use of a chain transfer agent in the presence of a highly active catalyst for precise control of molecular weight and chain shape during alternating copolymerization of carbon dioxide and epoxide, allowing for the production of low-molecular-weight poly(alkylene carbonate) with controlled properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If copolymerization is carried out without a chain transfer agent, then high molecular weight poly(alkylene carbonate) is produced, but the polymer has insufficient mechanical strength and limited applications due to low glass transition temperature
Solution Approach 1:
The patent applies parameter changes by introducing a chain transfer agent to control the molecular weight parameter of the polymer. By adjusting the amount and type of chain transfer agent (such as alcohols or carboxylic acids), the molecular weight is precisely controlled to produce low molecular weight poly(alkylene carbonate) with improved mechanical strength while maintaining the copolymerization process of carbon dioxide and epoxide.
2Strength
If methods are used to produce low molecular weight poly(alkylene carbonate), then mechanical properties are enhanced, but large amounts of catalysts are required making the process economically inefficient
Solution Approach 1:
The patent introduces a chain transfer agent as an intermediary substance that mediates between the catalyst and the monomers during copolymerization. This intermediary enables precise control of molecular weight without requiring excessive catalyst amounts. The chain transfer agent facilitates chain termination and initiation events that control polymer growth, allowing low molecular weight polymer production with reduced catalyst consumption and improved economic efficiency.
3Productivity
If high molecular weight poly(alkylene carbonate) is produced, then the polymerization process is efficient, but the polymer has low glass transition temperature and insufficient mechanical strength
Solution Approach 1:
The patent changes the molecular weight parameter through the introduction of a chain transfer agent during efficient copolymerization. This parameter change allows the process to maintain high productivity while producing low molecular weight polymer with superior mechanical properties. The chain transfer agent controls chain length without significantly affecting the overall polymerization rate, thus resolving the contradiction between productivity and mechanical strength.
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 method enables the production of poly(alkylene carbonate) with precisely controlled molecular weight and chain shape, enhancing its mechanical properties and diversifying its applications, while reducing catalyst usage and production costs.
Implementation Method 1
a method of precisely controlling the molecular weight and chain shape of a polymer using a compound having an alcohol or carboxylic acid functional group as a chain transfer agent when carrying out a process of preparing an alternating copolymer of carbon dioxide and epoxide
Implementation Method 2
using a catalyst comprising a trivalent metal complex synthesized from a quaternary ammonium salt-containing Salen type ligand
Data Source
AI summary
This invention relates to a method of preparing poly(alkylene carbonate) that has a molecular weight and polymer chain structure precisely controlled by adding a chain transfer agent composed of a compound having an alcohol or carboxylic acid functional group upon alternating copolymerization of an epoxide compound and carbon dioxide using a catalyst composed of a trivalent metal complex compound synthesized from a quaternary ammonium salt-containing Salen type ligand, and to a polymer compound prepared thereby. According to this invention, the polymer compound having a star-shaped chain as well as the polymer having a linear chain can be prepared. The low-molecular-weight poly(alkylene carbonate) has an —OH terminal group and can be used alone as a coating agent, etc., and also in mixtures with an isocyanate compound and thus can be easily utilized to prepare polyurethane.