Poly(alkylene terephthalate) Biocompatibility via Aliphatic Segments
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Solution Overview
Problem
Poly(ethylene terephthalate) (PET) is less suitable for medical applications due to insufficient flexibility and cell interactive properties, requiring additional processing steps like blending or surface modification to enhance biocompatibility and cell adhesion, which can lead to phase separation issues.
Innovation Solution
Development of linear poly(alkylene terephthalate) (PAT) polyesters with long aliphatic segments, produced through solution polycondensation at lower temperatures without catalysts, exhibiting increased flexibility and cell-interactive properties with endothelial cells, allowing for selective adhesion and proliferation without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PET is used for medical applications, then good thermal and mechanical properties are achieved, but flexibility and cell interactive properties are insufficient
Solution Approach 1:
The patent changes the chemical structure parameters of the polyester by incorporating long aliphatic chains (at least 4 methylene groups) between aromatic rings, which fundamentally alters the material's flexibility and cell interaction properties while maintaining mechanical strength. This structural parameter change enables the polymer to achieve both good mechanical properties and enhanced cell interactive properties.
Solution Approach 2:
The patent creates a composite-like structure within the polymer chain by combining aromatic rings (providing strength and thermal stability) with long aliphatic chains (providing flexibility and cell interaction). This molecular-level composite structure allows the single polymer to exhibit both rigid and flexible characteristics simultaneously, resolving the contradiction between mechanical strength and adaptability.
2Adaptability or versatility
If PET is blended with poly(butylene terephthalate) to increase flexibility, then flexibility is improved, but phase separation occurs
Solution Approach 1:
Instead of blending separate polymers, the patent merges the aromatic and aliphatic components into a single copolymer structure. The aromatic terephthalate units and aliphatic diol units are covalently bonded in the same polymer chain, ensuring molecular-level mixing and eliminating phase separation while maintaining the desired flexibility from the aliphatic segments.
Solution Approach 2:
The patent changes the compositional parameter by incorporating at least 4 methylene groups in the aliphatic chains, which provides sufficient flexibility without compromising compositional stability. This specific parameter threshold ensures the polymer achieves flexibility comparable to blended systems but without phase separation issues.
3Adaptability or versatility
If surface modification is applied to enhance biocompatibility, then cell adhesion is improved, but additional processing steps are required
Solution Approach 1:
The patent enables the polymer to provide its own cell-adhesive functionality through its intrinsic molecular structure. The long aliphatic chains and aromatic rings create a surface that naturally promotes cell adhesion and proliferation without requiring external surface modifications. The polymer serves itself by having the necessary biocompatible properties built into its base structure.
Solution Approach 2:
The patent changes the surface chemistry parameters by incorporating specific aliphatic chain lengths (at least 4 methylene groups) that naturally enhance cell interaction. This compositional parameter change provides inherent biocompatibility, eliminating the need for additional surface treatment processes.
4Productivity
If melt polycondensation is used to produce PAT polyesters, then polymer synthesis is achieved, but high temperatures and catalysts are required
Solution Approach 1:
The patent changes the reaction condition parameters by utilizing the specific chemical reactivity of acid chlorides, which allows polymerization to proceed at lower temperatures without catalysts. The acid chloride group is sufficiently reactive to form ester bonds under milder conditions compared to standard melt polycondensation, reducing the temperature parameter from 250°C to lower values.
Solution Approach 2:
The patent extracts the catalyst requirement from the polymerization process by using acid chloride monomers that self-react without needing external catalysts. This removal of the catalyst element simplifies the process and enables lower temperature operation, as catalysts are typically required to lower activation energy at high temperatures.
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 PAT polyesters demonstrate improved flexibility and biocompatibility, enabling effective cell adhesion and proliferation, particularly with endothelial cells, and can be processed under milder conditions, offering a cost-efficient and reproducible method for producing polymers with low polydispersity index.
Implementation Method 1
linear aromatic PAT polyesters, comprising an aliphatic chain of at least four or five methylene (-CH2-) groups, particularly as obtained by the method described herein
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
The present invention relates to poly(alkylene terephthalate) polyesters having long poly-methylene segments and their use in a wide variety of applications. Particularly, said PAT polyesters are used in biotechnological or biomedical applications, wherein the extent of cell adhesion, cell growth or cell interaction, in particular endothelial cells, depends on the odd or even number of carbon atoms in the aliphatic segments. Also provided are methods for the preparation of poly(alkylene terephthalates) (PAT) having long poly-methylene segments, wherein the bifunctional monomers, in particular terephthalic acid (or a derivative thereof) and an aliphatic diol, are dissolved in a solvent and the polycondensation reaction takes place in solution.