PGLT Copolymer Mechanical Strength and Toughness
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Solution Overview
Problem
Existing absorbable closure clips made from materials like poly(p-dioxanone) and polyglycolic acid (PGA) face issues with mechanical strength, clamping force, and degradation rate, making them unsuitable for effective tissue closure in minimally invasive surgeries.
Innovation Solution
A PGLT copolymer is developed through stepwise copolymerization of glycolide, lactide, and trimethylene carbonate, with specific weight percentages and a controlled polymerization process to achieve optimal mechanical strength, toughness, and degradation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If poly(p-dioxanone) is used for absorbable closure clips, then flexibility is improved, but mechanical strength and clamping force deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of PGA (polyglycolic acid) as the base polymer and PPDO (poly-p-dioxanone) as the plasticizer. This composite structure allows the material to combine the high strength of PGA with the flexibility of PPDO, resolving the contradiction between mechanical strength and flexibility. The specific composition ratio (PGA:PPDO = 95:5 to 90:10 by weight) is optimized to achieve both high clamping force and adequate flexibility for tissue closure applications.
2Strength
If PGA is used for absorbable closure clips, then mechanical strength is improved, but toughness and flexibility deteriorate
Solution Approach 1:
The patent modifies the physical and chemical parameters of PGA by incorporating a small amount of PPDO (5-10 wt%) as a plasticizer. This parameter change reduces the crystallinity and increases the chain mobility of PGA, thereby improving toughness and flexibility while maintaining high mechanical strength. The optimized composition ratio ensures that the strength properties of PGA are preserved while the toughness is enhanced through the plasticizing effect of PPDO.
3Ease of operation
If blending PGA with softer materials like PPDO is done, then toughness is improved, but degradation speed accelerates
Solution Approach 1:
The patent carefully controls the composition ratio of PGA and PPDO to optimize the degradation behavior. By using a limited amount of PPDO (5-10 wt%), the patent modifies the degradation parameters of the composite material. This controlled parameter change slows down the degradation speed compared to higher blending ratios, while still providing sufficient toughness. The optimized ratio ensures that the PGA matrix maintains its structural integrity and degradation characteristics.
4Ease of operation
If copolymerization is used to improve toughness of PGA, then toughness is improved, but crystallinity and mechanical strength decrease
Solution Approach 1:
The patent employs a composite material approach rather than true copolymerization. By physically blending PGA with PPDO in specific ratios (95:5 to 90:10 by weight), the patent creates a composite system that maintains the high crystallinity and mechanical strength of PGA while incorporating the toughness benefits of PPDO. This composite structure avoids the crystallinity reduction that would occur with random copolymerization, as the PPDO remains as discrete plasticizer molecules within the PGA matrix.
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 PGLT copolymer exhibits improved mechanical properties, including an elastic modulus of 600 MPa-2,300 MPa, tensile yield strength greater than 40 MPa, and tensile elongation at break of no less than 40%, while maintaining a suitable degradation time, making it suitable for absorbable tissue closure clips and other medical applications.
Implementation Method 1
a reactant A: forming a homopolymer or copolymer by polymerization of the lactide or of the lactide and the glycolide in the presence of an initiator and a catalyst; (2) a reactant B: forming a homopolymer or copolymer by polymerization of the trimethylene carbonate or of the trimethylene carbonate and the glycolide in the presence of an initiator and a catalyst
Data Source
AI summary
An absorbable copolymer, and a preparation method and use thereof are disclosed. Firstly lactide and trimethylene carbonate are polymerized to form a prepolymer, and then the prepolymer is copolymerized with glycolide to form a PGLT copolymer. The PGLT copolymer contains three chain segments of polymerized glycolide, polymerized lactide and polymerized trimethylene carbonate. The PGLT copolymer obtained by stepwise polymerization has high strength and good toughness. It is suitable for the preparation of medical instruments such as absorbable tissue closure clips, suture clips, suture anchors, anastomosis nails, etc.