Shape-Memory Polymer with Low Polydispersity for Body-Temperature Triggering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current shape-memory polymers (SMPs) have high shape-memory transition temperatures above human body temperature, limiting their applicability in biomedical devices, as they require high triggering temperatures and do not easily process into different shapes or exhibit reproducible behavior.
Innovation Solution
Development of SMPs with a composite prepolymer crosslinked using a stoichiometric amount of a multifunctional crosslinker, comprising a branched or telechelic prepolymer with low polydispersity reacted with a non-crystalline chain extender, allowing for deformation at or below room temperature and recovery at body temperature, with optional radical scavengers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional thermally induced shape-memory polymers are used, then high modulus and shape memory capability are achieved, but the triggering temperature is too high (50-90°C) for biomedical applications
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition and molecular weight of polymer segments to systematically adjust the shape memory transition temperature. By changing the glass transition temperature of soft segments and melting temperature of hard segments through compositional variation, the triggering temperature is precisely tuned to body temperature range (35-42°C), resolving the contradiction between achieving shape memory effect and biomedical compatibility
Solution Approach 2:
The patent employs composite materials by creating block copolymers with distinct soft and hard segments that have different thermal properties. The soft segments (amorphous, low Tg) and hard segments (crystalline, high Tm) work together to achieve shape memory effect at body temperature, combining the advantages of both segment types to resolve the temperature adaptability contradiction
2Adaptability or versatility
If polymers with low transition temperature near body temperature are used, then biomedical applicability is improved, but the modulus and mechanical strength are reduced
Solution Approach 1:
The patent applies segmentation by dividing the polymer into functionally distinct soft segments (providing flexibility and low Tg) and hard segments (providing strength and high Tm). This segmentation allows each segment to contribute its specific properties, with hard segments forming reinforcing domains that maintain mechanical strength while soft segments enable body temperature triggering
Solution Approach 2:
The patent implements local quality by creating regions with different mechanical and thermal properties within the same material. The hard segments form localized crystalline domains with high strength and stiffness, while the soft segments provide amorphous regions with flexibility and low transition temperature, allowing the material to exhibit both strength and low triggering temperature simultaneously
3Temperature
If phase-segregated hard and soft segment domains are created, then shape memory transition temperature is reduced, but the structural complexity increases
Solution Approach 1:
The patent applies self-service by allowing the block copolymer to spontaneously self-assemble into phase-separated hard and soft segment domains during processing. The thermodynamic incompatibility between segments drives automatic phase separation and domain formation without requiring complex external processing or additional agents, reducing structural complexity while achieving the desired temperature reduction
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 SMPs exhibit a triggering temperature near body temperature, enabling efficient mechanical work performance and high shape recovery efficiency, suitable for biomedical applications such as compressive clothing and medical devices.
Implementation Method 1
The large-strain recovery observed in SMPs is a manifestation of entropy elasticity
Implementation Method 2
A shape-memory material can be deformed to a temporary shape and can return to its original shape after the application of the external stimulus. For example, a material heated above its shape-memory transition temperature, TSM
Data Source
AI summary
Described are shape-memory polymers that have a composite prepolymer crosslinked with a stoichiometric amount of a multifunctional crosslinker, the composite prepolymer having a branched or telechelic prepolymer having a low polydispersity reacted with a non-crystalline chain extender. Also described are methods of making shape-memory polymers by reacting a branched or telechelic prepolymer having a low polydispersity with a non-crystalline chain extender to form a composite prepolymer, and crosslinking a stoichiometric amount of a multifunctional crosslinker with the composite prepolymer, thereby forming the shape-memory polymer.