Amorphous Thiourethane Polymers for Bio-Electronic Devices

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Solution Overview

Problem

Chronically implanted bio-electronic devices often fail due to neuroinflammatory responses and mechanical mismatch with surrounding tissue, as existing shape memory polymer substrates either have high elastic modulus or high cure stresses, making them difficult to fabricate and implant successfully.

Innovation Solution

Development of amorphous thermoset thiourethane polymers with a sequential chain of thiol-functionalized and isocyanate-functionalized monomers, which undergo a significant decrease in modulus upon glass transition, matching the mechanical properties of biological tissue and allowing for softening in vivo while maintaining mechanical integrity and toughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If shape memory polymer substrates are used to match mechanical properties of tissue, then mechanical compatibility is improved, but fabrication difficulty increases due to high cure stresses

Engineering Contradiction:

Improvemechanical compatibilityVSAvoidfabrication difficulty

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent changes the chemical composition parameters by using thiol-functionalized monomers with specific molecular weights and ratios (e.g., 2,2′-(ethylenedioxy)diethanethiol, 1,3-propanedithiol, 1,4-butanedithiol) to control cure stress and glass transition temperature, enabling both low fabrication stress and appropriate mechanical softening in vivo

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite polymer system combining thiol-functionalized monomers with isocyanate-functionalized monomers in specific ratios, forming a thermoset network that achieves both low cure stress and appropriate mechanical properties through the synergistic interaction of different monomer types

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If substrate modulus is reduced to match tissue, then mechanical compatibility is improved, but structural integrity deteriorates

Engineering Contradiction:

Improvemechanical compatibilityVSAvoidstructural integrity

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent implements a dynamic modulus transition where the substrate maintains high stiffness (glass transition temperature 0-80°C) during fabrication and implantation, then transitions to low stiffness (rubbery state) in vivo through thermal softening, achieving both structural integrity and mechanical compatibility at different stages

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent controls the glass transition temperature parameter (Tg) within 0-80°C range through monomer selection and ratio adjustment, enabling the substrate to be rigid at fabrication temperatures but soft at body temperature, thus maintaining structural integrity during manufacturing while achieving tissue compatibility in vivo

Inventive Principle:

Principle #35Parameter changes

3Strength

If thermoset polymers are used for mechanical stability, then structural integrity is improved, but softening capability deteriorates

Engineering Contradiction:

Improvemechanical stabilityVSAvoidsoftening capability

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The patent adjusts the crosslink density parameter through monomer ratio control (e.g., using 1:1 molar ratio of thiol-functionalized to isocyanate-functionalized monomers) to achieve an optimal balance where the thermoset network provides sufficient mechanical stability while allowing adequate softening through glass transition at physiological temperatures

Inventive Principle:

Principle #35Parameter changes

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 amorphous thermoset thiourethane polymers achieve a three-order-of-magnitude softening in simulated in vivo conditions, reducing inflammation and mechanical failure, and are thermally stable for compatibility with photolithographic processes, enhancing the longevity and chronic performance of bio-electronic devices.

Implementation Method 1

Shape memory thermoset polymers can undergo a glass transition, resulting in a large decrease in modulus

Methodology Applied

Scientific EffectGlass transition: Phase Change

Implementation Method 2

an anionic step-growth polymerization reaction to form a sequential chain of the first type of monomer covalently bonded to the second type of monomer via thiourethane linkages

Methodology Applied

Scientific EffectStep-growth polymerization: Chemical Bonding

Data Source

PatentUS11155670B2Amorphous thermoset thiourethane polymers, method of synthesis thereof and use in bio-electronic devices

Publication Date: 2021.10.26 BOARD OF RGT THE UNIV OF TEXAS SYST

AI summary

An amorphous thermoset thiourethane polymer, comprising a sequential chain of a first type of monomer covalently bonded to a second type of monomer via thiourethane linkages, wherein the first type of monomer includes two or more thiol functional groups and the second type of monomer includes two or more isocyanate functional groups. Methods of synthesizing the polymer, bio-electronic devices comprising the polymer and methods of manufacturing such devices are disclosed.