Multi-Transition Shape Memory Polymer Networks for Biomedical Implants
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Solution Overview
Problem
Existing shape memory elastomers (SMEs) face challenges in maintaining mechanical robustness and biocompatibility while transitioning at physiological temperatures, with unsuitable transition temperatures and poor mechanical properties limiting their application in biomedical implants.
Innovation Solution
A biocompatible, biodegradable copolymer network comprising poly(glycerol dodecanoate acrylate) (PGDA) and polyacrylic acid (PAA) with optional inclusion of poly(10-undecenoic acid) (PUA) to achieve multiple transition temperatures and controlled shape changes, tailored for biomedical implants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional SMEs are designed to transform at physiological temperatures, then shape memory functionality is achieved, but mechanical robustness deteriorates
Solution Approach 1:
The patent employs composite materials by combining a shape memory polymer matrix with reinforcing filler particles. This composite structure allows the material to maintain shape memory functionality at physiological temperatures while the filler particles provide mechanical reinforcement to prevent brittleness and maintain robustness during transformation and usage.
Solution Approach 2:
The patent utilizes parameter changes by carefully selecting and adjusting the transition temperature of the shape memory polymer to match physiological conditions (around 37°C). By optimizing this temperature parameter and controlling the polymer composition, the material achieves reliable shape transformation at body temperature while maintaining adequate mechanical properties through proper material selection and crosslinking density control.
2Object-affected harmful factors
If transition temperature is set for physiological conditions, then biocompatibility is improved, but mechanical integrity above transition temperature deteriorates
Solution Approach 1:
The composite structure with filler particles provides mechanical reinforcement that stabilizes the polymer matrix above the transition temperature. The filler particles maintain structural integrity and prevent excessive deformation or failure when the shape memory polymer undergoes transformation at physiological temperatures, thus preserving mechanical integrity while maintaining biocompatibility.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating reinforcing fillers into the polymer matrix before transformation occurs. This pre-established reinforcement structure cushions against the mechanical stresses that would otherwise cause failure during the transformation process or above the transition temperature, ensuring the material maintains sufficient integrity for biomedical applications.
3Strength
If elastomeric properties are enhanced, then flexibility is improved, but transition temperature control deteriorates
Solution Approach 1:
The patent achieves precise transition temperature control by adjusting polymer composition parameters, crosslinking density, and filler content. These parameter changes allow fine-tuning of the transformation temperature to match physiological conditions while maintaining adequate elastomeric properties through proper material selection and formulation.
Solution Approach 2:
The patent applies local quality by creating a heterogeneous structure where the polymer matrix provides elastomeric properties and shape memory functionality, while the filler particles provide mechanical reinforcement. This localized differentiation of material properties allows simultaneous achievement of flexibility and precise transition temperature control.
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 SMEs exhibit tunable mechanical properties, high elasticity, and biocompatibility, enabling precise shape transitions and controlled degradation, suitable for minimally invasive surgical applications.
Implementation Method 1
SMEs are materials that can undergo reversible transformations between desired pre-programmed shapes in response to external stimuli
Implementation Method 2
The second polymer is both biocompatible and biodegradable, is hydrophilic, and contains one or more functional groups that can form hydrogen bonds
Data Source
AI summary
Described herein are shape memory elastomers (SMEs) each comprising a copolymer network structure. The network comprises two distinct polymer components: a first polymer that is a biocompatible, biodegradable shape memory polymer exhibiting hydrophobic properties, and a second polymer that is covalently bonded to the first via the covalent or/and noncovalent interactions. This second polymer is distinguished by its biocompatible, biodegradable, and hydrophilic nature, featuring functional groups with hydrogen bonding capabilities. The network can also incorporate a third polymer, resulting in an SME with multiple shape transition properties. The SMEs described herein have unique potential as biomedical implants. Methods of manufacture are also provided.