Absorbable Copolyester for Surgical Sutures and Microspheres
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Solution Overview
Problem
There is a need for a synthetic absorbable polymer that balances mechanical strength with fast absorption or hydrolysis, particularly for surgical sutures and microspheres used in injectable compositions or drug delivery carriers, as existing methods either compromise on mechanical properties or struggle with reproducible pre-degradation and controlled absorption rates.
Innovation Solution
A semi-crystalline, absorbable copolyester comprising the reaction product of poly(ethoxyethylene diglycolate) and glycolide, with a weight ratio of 30 to 60% poly(ethoxyethylene diglycolate), which is synthesized using diglycolic acid and diethylene glycol, and further modified with lactone monomers to achieve the desired mechanical strength and absorption rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crystallinity of the polymer is increased to improve mechanical strength, then the absorption rate decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer by incorporating specific lactone monomers (glycolide, L-lactide, D-lactide) in controlled ratios with diglycolic acid and diethylene glycol. This compositional parameter change enables the polymer to achieve both high crystallinity (for mechanical strength) and fast absorption rate, resolving the contradiction between these two properties.
Solution Approach 2:
The patent creates a composite polymer structure by copolymerizing multiple monomers (diglycolic acid, diethylene glycol, and lactone monomers) to form a copolyester with semi-crystalline characteristics. This composite material approach allows the polymer to exhibit both high mechanical strength and controlled absorption properties that cannot be achieved with single-component polymers.
2Loss of time
If lactone monomers are used to disrupt crystallinity and increase absorption rate, then the polymer becomes more hydrophobic and absorption slows down
Solution Approach 1:
The patent optimizes the ratio parameters of hydrophilic (diglycolic acid, diethylene glycol) and hydrophobic (lactone monomers) components to achieve the desired balance between absorption rate and hydrophilicity. By controlling the compositional parameters within specific ranges, the patent resolves the contradiction between increasing absorption rate and maintaining hydrophilic character.
3Loss of time
If PEG is added to increase hydrophilicity and absorption rate, then mechanical properties deteriorate
Solution Approach 1:
Instead of using PEG as an additive, the patent incorporates hydrophilic ether groups directly into the polymer backbone through the diglycolic acid-d diethylene glycol component. This creates an intrinsic composite structure where the polyether segments are chemically bonded to the polyester segments, providing both hydrophilicity and mechanical strength without the phase separation and property degradation associated with PEG blending.
4Loss of time
If pre-degradation is applied to control absorption rate, then quality and stability control becomes difficult
Solution Approach 1:
The patent performs preliminary structural design during polymer synthesis by incorporating specific monomer ratios and molecular weight distributions that pre-determine the degradation behavior. This preliminary action during manufacturing allows controlled absorption rates to be achieved through the polymer's inherent structure rather than post-synthesis degradation treatment, ensuring consistent quality and stability.
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 copolyester exhibits enhanced mechanical strength, fast absorption, and controlled release properties, suitable for surgical sutures and microspheres, while maintaining dimensional stability and homogeneous encapsulation of pharmaceutical substances.
Implementation Method 1
the greater the crystallinity of an absorbable polymer, the slower the rate of the absorption will be... to increase the absorption or hydrolysis rate of absorbable polymers
Data Source
AI summary
A semi-crystalline, absorbable copolyester composition comprising the reaction product of a polycondensation polyester and at least one lactone, wherein the polycondensation polyester comprises the reaction product of diglycolic acid and/or a derivative thereof and diethylene glycol; and the copolyester comprises about 30 to 60% by weight of the polycondensation polyester based on the total weight of the copolyester. Also medical devices such as absorbable sutures comprising such copolyesters and absorbable microspheres comprising such copolyesters and methods of making of such absorbable microspheres.