Macroporous PVDF Membranes via Non-Toxic VIPS
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Solution Overview
Problem
Current methods for producing PVDF membranes using VIPS method rely on toxic solvents, and existing non-toxic solvents have not been effectively combined with VIPS for forming porous PVDF membranes, resulting in suboptimal membrane properties such as porosity, hydrophobicity, and processing efficiency.
Innovation Solution
The use of dimethyl sulfoxide (DMSO) as a solvent in combination with the VIPS method for phase separation, allowing for the production of high-porosity, hydrophobic, and isotropic PVDF membranes with improved mechanical stability and vapor transport rates, while being non-toxic and reducing processing times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If toxic solvents such as DMF, DMAc, NMP are used to dissolve PVDF for membrane preparation, then good membrane formation and porosity are achieved, but the solvent toxicity and environmental harm increase
Solution Approach 1:
The invention changes the chemical parameter of the solvent from toxic (DMF, DMAc, NMP) to non-toxic (DMSO). This parameter change allows the membrane formation process to maintain good porosity and morphology while eliminating the harmful effects of traditional solvents. The DMSO solvent system achieves effective phase separation and pore formation without the toxicity issues of conventional solvents.
Solution Approach 2:
The invention replaces expensive and hazardous solvent systems with a simpler, safer alternative. DMSO is not only non-toxic but also allows for easier handling and disposal compared to traditional solvents that require special waste treatment protocols. This substitution reduces both the environmental burden and the operational complexity associated with toxic solvent management.
2Object-affected harmful factors
If non-toxic solvents are used to dissolve PVDF, then solvent safety is improved, but the membrane properties such as porosity, hydrophobicity, and structural quality deteriorate
Solution Approach 1:
The invention optimizes the parameters of the DMSO solvent system, including concentration, temperature, and phase separation conditions, to achieve the desired membrane properties. By carefully controlling these parameters, the invention maintains high porosity and appropriate pore size distribution while using the non-toxic DMSO solvent. The parameter optimization ensures that membrane quality is not compromised by the switch to a safer solvent.
Solution Approach 2:
The invention utilizes phase transition mechanisms during membrane formation from the DMSO solution. The phase separation process from the DMSO-based casting solution creates the desired porous structure and morphology. This phase transition approach ensures that even with a non-toxic solvent, the membrane achieves the necessary porosity, hydrophobicity, and structural integrity for functional performance.
3Manufacturing precision
If traditional solvents are used with VIPS method, then phase separation and pore formation occur, but the processing time remains extended due to solvent removal and treatment requirements
Solution Approach 1:
The invention employs a solvent system that requires minimal post-processing time. DMSO's favorable evaporation characteristics and lack of toxicity mean that solvent removal and treatment steps are significantly reduced compared to traditional solvents. This reduces the overall processing time while maintaining effective pore formation through the VIPS method.
Solution Approach 2:
The invention optimizes the VIPS process parameters when using DMSO as the solvent, including exposure time, temperature, and humidity control. These parameter adjustments are specifically tailored to the DMSO solvent system to achieve rapid and efficient phase separation, reducing the time required for membrane formation while ensuring high-quality pore structure development.
4Object-affected harmful factors
If DMSO is used as a solvent with VIPS method, then non-toxic membrane production is achieved, but the compatibility and effectiveness of the solvent-VIPS combination is unproven
Solution Approach 1:
The invention systematically optimizes the parameters of the DMSO-VIPS process combination, including solvent concentration, casting conditions, phase separation temperature, humidity, and time. Through this parameter optimization, the invention establishes reliable and reproducible membrane formation using the DMSO-VIPS combination, proving its effectiveness for producing membranes with controlled porosity, pore size, and structural quality.
Solution Approach 2:
The invention leverages the phase transition behavior of DMSO during the VIPS process to ensure reliable membrane formation. By understanding and controlling the phase separation mechanics specific to the DMSO-VIPS system, the invention achieves consistent and reproducible pore formation, validating the reliability of this non-toxic solvent combination for industrial membrane production.
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
This approach results in PVDF membranes with enhanced porosity, hydrophobicity, and vapor transport rates, achieving higher liquid entry pressure and water vapor transport rates compared to commercially available membranes, with a narrow pore size distribution and improved mechanical stability.
Implementation Method 1
mixing a PVDF polymer with dimethyl sulfoxide (DMSO), obtaining a solution containing PVDF
Implementation Method 2
the cast film is exposed to an atmosphere of a non-solvent vapour which gives rise to phase separation by penetrating the cast film
Implementation Method 3
phase separation by penetrating the cast film
Data Source
Figure 1
Figure 2A~2D
AI summary
The invention relates to macroporous, hydrophobic and isotropic polyvinylidene fluoride (PVDF) membranes having improved properties and to a new method for preparing the same.