Silicone-Urethane Copolymers for Biocompatible Melt-Processing
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Solution Overview
Problem
There is a need for polymers that combine the feel and characteristics of silicones with the physical properties of polyurethanes, such as elasticity and melt-processability, while also being biocompatible and biodurable.
Innovation Solution
The development of silicone-urethane copolymers through a one-step reaction involving a diisocyanate, a polycarbonate diol, a polysiloxane, a C2-8 diol chain extender, and optionally a monofunctional siloxane chain terminator, which results in copolymers with high silicone content, exhibiting both elastomeric and thermoplastic properties, and can include antimicrobial additives like silver-containing compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional silicones are used, then elastomeric properties and feel are achieved, but melt-processability and thermoplastic characteristics are lost
Solution Approach 1:
The patent creates a composite polymer system by copolymerizing siloxane segments with polyurethane segments. The siloxane segments (from polysiloxane and diol chain extender) provide elastomeric properties and silicone feel, while the polyurethane segments (from diisocyanate and polycarbonate diol) provide thermoplastic characteristics and melt-processability. This composite structure allows the material to exhibit both silicone-like elasticity and thermoplastic processing capabilities.
2Strength
If high silicone content is incorporated, then silicone characteristics and feel are improved, but biocompatibility and biodurability may be compromised
Solution Approach 1:
The patent carefully controls the molecular weight of the polysiloxane (500-8000 Da, preferably 1000-2500 Da) and the composition ratios of components to optimize both silicone characteristics and biocompatibility. By adjusting these parameters, the copolymer achieves high silicone content (at least 5-30% by weight) while maintaining biocompatibility and biodurability suitable for medical applications.
Solution Approach 2:
The copolymer structure combines siloxane segments with biocompatible polyurethane segments. The polyurethane portions (from biocompatible diisocyanate and polycarbonate diol) provide the biocompatibility and biodurability framework, while the siloxane segments contribute silicone characteristics. This composite approach allows high silicone content without sacrificing biocompatibility.
3Ease of operation
If polyurethanes are used, then elasticity and melt-processability are achieved, but silicone feel and characteristics are lost
Solution Approach 1:
The patent creates a copolymer where polyurethane segments (from diisocyanate and polycarbonate diol) provide melt-processability and elasticity, while incorporated siloxane segments (from polysiloxane and diol chain extender) provide silicone feel and characteristics. The resulting copolymer exhibits both thermoplastic processing capabilities and silicone-like surface properties.
4Adaptability or versatility
If multiple components are combined in copolymerization, then desired property combination is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent divides the polymer structure into distinct segments: siloxane segments (from polysiloxane and diol chain extender) and polyurethane segments (from diisocyanate and polycarbonate diol). This segmentation allows each component to contribute specific properties while the overall copolymer structure maintains processability. The one-step copolymerization method integrates these segments efficiently without requiring complex multi-step manufacturing processes.
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 resulting copolymers demonstrate desirable properties like high tensile strength, chemical resistance, and elasticity, with the ability to be processed into pellet form for applications such as implantable medical devices, reducing the risk of bacterial growth and foreign body-induced infections.
Implementation Method 1
the reaction product of a one-step reaction of reactants comprising a diisocyanate, a polycarbonate diol, a polysiloxane, a C2-8 diol chain extender
Implementation Method 2
in the presence of a catalyst to initiate a one-step polymerization reaction
Implementation Method 3
The temperature of the reaction mixture is monitored, and the admixing step is terminated when the reaction mixture reaches a predefined temperature
Implementation Method 4
The method further comprises curing the silicone-urethane copolymer, for example, by heating in an oven for a suitable period of time to ensure completion of the reaction
Data Source
AI summary
The invention relates to silicone-urethane copolymers and methods for making the copolymers. The silicone-urethane copolymers can have many physical properties usually associated with polyurethanes but also the feel and characteristics of silicones.