Asymmetric Isoporous Membrane via Thermal Phase Separation
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Solution Overview
Problem
Existing methods for preparing asymmetric isoporous membranes, such as the SNIPS process, face challenges in achieving high flux and selectivity due to dense and compact cross-sections, and they often use toxic solvents, leading to environmental concerns and waste generation.
Innovation Solution
A thermally induced phase separation process using a bio-based green solvent to create a membrane casting solution that is phase homogeneous at high temperatures and undergoes phase separation at low temperatures, resulting in an asymmetric isoporous membrane with a loose cross-section, improved permeability, and high strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the SNIPS process is used to prepare asymmetric isoporous membrane, then the pore regularity is improved, but the cross-section becomes dense and compact resulting in low permeability
Solution Approach 1:
The patent changes the fundamental parameter of phase separation induction from chemical (non-solvent) to physical (temperature). By using thermally induced phase separation instead of non-solvent induced phase separation, the membrane forms a loose cross-section with improved permeability while maintaining isoporous structure regularity through temperature-controlled phase separation.
Solution Approach 2:
The patent utilizes thermal phase transition of the casting solution to induce phase separation. The temperature-dependent phase transition creates a loose cross-sectional structure during membrane formation, allowing high permeability while maintaining pore regularity through controlled cooling and phase separation.
2Ease of manufacture
If traditional solvents are used in the SNIPS process, then the membrane formation is facilitated, but toxic waste liquid is generated causing environmental harm
Solution Approach 1:
The patent changes the solvent parameter from toxic organic solvents to green solvents (water, alcohols, esters). This substitution maintains effective membrane formation capability while eliminating toxic waste generation, achieving ease of manufacture through green chemistry principles.
Solution Approach 2:
The patent converts the previously harmful toxic solvents into beneficial green solvents. By selecting environmentally friendly solvents that still provide effective membrane formation, the process transforms environmental harm into benefit while maintaining manufacturing effectiveness.
3Manufacturing precision
If multiple conditions are controlled in the SNIPS process, then the isoporous structure is achieved, but the process complexity increases
Solution Approach 1:
The patent changes the control parameter from multiple chemical variables (solvent properties, non-solvent conditions, solution concentration) to a single primary parameter (temperature). This simplification maintains isoporous structure quality while reducing process complexity through thermal control.
Solution Approach 2:
The patent makes temperature control serve multiple functions: it controls phase separation, regulates solvent evaporation, and determines membrane morphology. This multi-functionality of temperature control reduces the need for multiple separate control mechanisms, simplifying the overall process while achieving precise isoporous structure.
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 method achieves a significant increase in permeability while maintaining selectivity, and it promotes environmental friendliness by using a green solvent system and enabling solvent recycling, thereby reducing waste and toxicity.
Implementation Method 1
a thermally induced phase separation process... the block copolymer solution is in a macroscopic homogeneous state within this temperature range and has thermally stable properties... the membrane casting solution show phase homogeneity at high-temperature and phase separation at low-temperature
Data Source
AI summary
A method for preparing an asymmetric isoporous membrane with loose cross-section based on a thermally induced phase separation process, and an asymmetric isoporous membrane prepared provided. The prepared isoporous membrane show loose cross-section, high permeability, and high strength, and the fabricating process used recyclable and non-toxic dilutes as the solvents.