Biodegradable Terpolymer Pressure-Sensitive Adhesive

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Solution Overview

Problem

Commercially available pressure-sensitive adhesives (PSAs) are not biodegradable and thus limited in biomedical and other applications where biocompatibility and degradation into metabolizable components are required.

Innovation Solution

Development of a biocompatible and biodegradable poly(D,L-lactide-co-glycolide-co-ε-caprolactone) pressure-sensitive adhesive with specific molecular weight and polydispersity index ranges, and blends thereof, which can be coated on conformable backing members and optionally include bioactive agents, to provide adhesive properties without the need for cure time or additional processing steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If commercially available PSAs are used, then adhesive properties and ease of manufacture are improved, but biodegradability and biocompatibility deteriorate

Engineering Contradiction:
Improveease of manufactureVSAvoidbiodegradability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the adhesive by using biodegradable polymers (poly(D,L-lactide-co-glycolide-co-ε-caprolactone)) instead of conventional petroleum-based polymers. This parameter change maintains adhesive functionality while achieving biodegradability and biocompatibility, resolving the contradiction between ease of manufacture and biodegradability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material formulation by creating terpolymer blends with specific molecular weight distributions and compositions. The composite nature of the terpolymer system allows optimization of both processing characteristics (ease of manufacture) and biodegradation properties, simultaneously addressing both requirements.

Inventive Principle:
Principle #40Composite materials

2Reliability

If biodegradable polymers are used to achieve biocompatibility, then biodegradability is improved, but adhesive strength and reliability may deteriorate

Engineering Contradiction:
ImprovebiocompatibilityVSAvoidadhesive strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent optimizes physical parameters of the biodegradable polymer including molecular weight (140,000 Daltons or less) and polydispersity index (less than 2.0). These parameter adjustments ensure the polymer achieves sufficient adhesive strength and tackiness while maintaining biocompatibility and biodegradability, resolving the contradiction between reliability and strength.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies different molecular weight terpolymer components in specific ratios (blend compositions) to create local variations in adhesive properties. This allows optimization of adhesive strength in critical areas while maintaining overall biocompatibility, resolving the contradiction between strength and biocompatibility.

Inventive Principle:
Principle #3Local quality

3Reliability

If polymer molecular weight is reduced to improve degradation rate, then biodegradability is improved, but mechanical strength and adhesive properties deteriorate

Engineering Contradiction:
Improvebiodegradation rateVSAvoidmechanical strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent precisely controls the molecular weight parameter at 140,000 Daltons or less and polydispersity index below 2.0. This parameter optimization achieves the optimal balance where the polymer degrades at a suitable rate while maintaining sufficient mechanical strength and adhesive properties, resolving the contradiction between biodegradation rate and mechanical strength.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite terpolymer blends combining different molecular weight components. This composite approach allows the system to achieve fast degradation rates from lower molecular weight components while lower molecular weight components contribute to adhesive properties, resolving the contradiction between degradation rate and mechanical strength.

Inventive Principle:
Principle #40Composite materials

4Strength

If PSA formulation is optimized for adhesive strength, then adhesive strength is improved, but biodegradability and metabolizability deteriorate

Engineering Contradiction:
Improveadhesive strengthVSAvoidmetabolizability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent changes the fundamental chemical composition parameter by selecting biodegradable terpolymer chemistry (poly(D,L-lactide-co-glycolide-co-ε-caprolactone)) that inherently provides both adhesive strength and metabolizability. This parameter change resolves the contradiction by achieving both adhesive performance and biodegradability simultaneously rather than trading one for the other.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2611868B1Biodegradable terpolymers and terpolymer blends as pressure-sensitive adhesives
Publication Date: 2020.01.08 SURMODICS PHARMACEUTICAL INC
  • EP2611868B1 patent drawingFigure 1~5
  • EP2611868B1 patent drawingFigure 6~7

AI summary

Disclosed herein are terpolymers and blends prepared from polyester terpolymers that can function as pressure-sensitive adhesives. The disclosed articles comprise the terpolymer and terpolymer blends coated to a conformable backing member. The terpolymer and terpolymer blends can further comprise a bioactive agent.