Copolymer Polyester Membrane Composition for Room-Temperature Phase Separation
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Solution Overview
Problem
Conventional ultrafiltration membranes using polysulfone and polyether sulfone polymers have low water permeability due to hydrophobicity, leading to membrane contamination, while polyester membranes face solubility issues in organic solvents, requiring high temperatures for phase separation, increasing energy consumption and costs.
Innovation Solution
A copolymerized polyester is developed through an esterification reaction between C8-12 aromatic dicarboxylic acid and C2-10 linear or branched aliphatic polyhydric alcohol, with a molar ratio of 2.7 to 6, allowing solubility in organic solvents at room temperature, enabling phase separation without heating and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional polyester (polyethylene terephthalate) is used to form ultrafiltration membrane, then the membrane structure can be formed, but the solubility in polar aprotic organic solvents at room temperature is low due to semi-crystalline nature and high polymer polarity, requiring high temperature (60°C) processing
Solution Approach 1:
The patent modifies the chemical composition parameters of polyester by incorporating specific comonomers (isophthalic acid 10-50 mol%, cycloaliphatic dicarboxylic acid 5-40 mol%, and/or aromatic dicarboxylic acid other than terephthalic acid 5-50 mol%) to change the polymer's solubility characteristics. This compositional parameter change enables room temperature processing while maintaining membrane-forming capability, directly resolving the contradiction between processing temperature and energy consumption
Solution Approach 2:
The patent creates a composite polyester material by copolymerizing multiple dicarboxylic acid components with diols. This composite structure combines the benefits of different monomers: terephthalic acid provides mechanical strength, while isophthalic acid and cycloaliphatic dicarboxylic acids improve solubility by disrupting crystallinity. The resulting composite polyester achieves both processability at room temperature and adequate membrane performance
2Adaptability or versatility
If conventional polyester is used, then the membrane can be formed, but high temperature processing is required which makes it difficult to optimize membrane-forming performance under various temperature conditions
Solution Approach 1:
By changing the chemical composition parameters of the polyester (incorporating isophthalic acid, cycloaliphatic dicarboxylic acid, and/or aromatic dicarboxylic acid in specific amounts), the patent adjusts the polymer's glass transition temperature, crystallinity, and solubility characteristics. This enables the membrane-forming process to be optimized across various temperature conditions, particularly enabling room temperature processing while maintaining controllable phase separation and pore formation
3Reliability
If hydrophobic polymers (polysulfone, polyether sulfone) are used for ultrafiltration membrane, then the membrane structure is formed, but water permeability is low due to hydrophobicity, leading to membrane contamination
Solution Approach 1:
The patent fundamentally changes the chemical composition parameters of the membrane material from hydrophobic polymers to polyester with specific hydrophilic comonomers. The incorporation of isophthalic acid, cycloaliphatic dicarboxylic acid, and/or aromatic dicarboxylic acid creates a more hydrophilic polymer structure that inherently resists organic contamination while maintaining adequate mechanical strength and membrane-forming capability
Solution Approach 2:
The patent uses composite polyester material combining multiple dicarboxylic acid components to achieve a balance between hydrophilicity (for contamination resistance) and mechanical properties (for membrane integrity). This composite approach allows the membrane to resist organic contamination better than conventional hydrophobic polymers while maintaining structural stability
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 copolymerized polyester enables low-cost production of ultrafiltration membranes with high water permeability and resistance to membrane contamination, enhancing mechanical durability through improved adhesion to nonwoven fabrics and polyamide layers.
Implementation Method 1
enabling phase separation without heating
Data Source
AI summary
The present invention relates to an organic solvent-soluble copolymerized polyester, a composition for forming an ultrafiltration membrane including the same, and a high water-permeability reverse osmosis membrane prepared therefrom. More specifically, the present invention relates to a polyester that has a high solubility in organic solvents at room temperature and thus can be used to produce ultrafiltration membranes at low cost, a composition for forming an ultrafiltration membrane including the same, and a high water-permeability reverse osmosis membrane prepared therefrom, wherein the reverse osmosis membrane has a reduced production cost and high water permeability.