Thiol-ene copolymer modulus tuning for soft tissue matching
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Solution Overview
Problem
Silicone polymers have a modulus in the gigapascal range, which is not suitable for applications requiring a lower modulus, limiting their use in applications that need rubbery properties similar to silicone but with a significantly lower elasticity.
Innovation Solution
A polymer formed from a mixture of mutually miscible monomers, including multifunctional thiol and alkene monomers, that can be polymerized under ambient conditions, exhibiting a tangent delta ranging from 0.1 to 1 at 20° C. and 37° C., allowing for a wide range of moduli from 1 kPa to 100 MPa, suitable for near-net shape processing and 3D printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If silicone polymers are used to achieve rubbery properties, then elasticity and rubbery behavior are improved, but modulus becomes too high (gigapascal range) for applications requiring softer materials
Solution Approach 1:
The patent employs composite materials by combining multiple monomer types (thiol, acrylate, ene, and epoxy monomers) to create a polymer network that achieves rubbery properties with tunable modulus. This composite approach allows the material to exhibit silicone-like elasticity while maintaining a lower, application-specific modulus through controlled crosslinking density and monomer composition.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying monomer composition, functionality, and crosslinking density to tune the final polymer modulus across several orders of magnitude. By adjusting the ratio of thiol to ene monomers and selecting monomers with different glass transition temperatures, the material can be optimized for specific modulus requirements while maintaining rubbery behavior.
2Strength
If polymer crosslinking is increased to improve mechanical properties, then strength and stability are improved, but processability and ease of manufacturing deteriorate
Solution Approach 1:
The patent applies preliminary action by designing monomers with predetermined reactivity ratios and functionalities that enable controlled crosslinking during processing. The thiol-ene click chemistry system allows crosslinking to proceed at ambient or mild conditions with predictable kinetics, enabling the material to be processed in near-net-shape configurations before final curing, thus balancing processability with mechanical property development.
Solution Approach 2:
The patent implements dynamics by utilizing a stepwise crosslinking mechanism where the polymer network forms progressively during processing. The thiol-ene reaction allows for controlled gelation and network formation that can be paused or continued based on processing requirements, enabling dynamic adjustment of material properties during manufacturing operations.
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 polymers demonstrate tunable viscoelastic behavior, matching or exceeding the modulus of soft tissues, enabling complex shape manufacturing and interaction with skin, with applications in flexible electronic devices, biomedical devices, and high-temperature environments, while being processable through casting and additive manufacturing techniques.
Implementation Method 1
A polymer formed from a mixture of mutually miscible monomers that can be polymerized under ambient conditions... at least one of the mutually miscible monomers is a multifunctional thiol monomer and at least one of the monomers is a multifunctional alkene
Data Source
AI summary
Embodiments of the invention are directed to softening amorphous polymeric materials based on a combination of thiol, acrylate, ene and epoxy monomers. These materials can soften to the modulus of tissue, have a sharp transition and are highly tunable. The materials have a glassy modulus of 1-7 GPa and exhibit a rubbery plateau in modulus that can range from 100 MPa down to as low as 0.03 MPa, which is at or below the modulus of tissue. They have potential uses as materials for near net shape processing such as casting, stereolithography, reaction injection molding, fused deposition molding and various other forms of 3D printing.