Gas-Tunable Membrane with CO2-Responsive Polymer Chains
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ultrafiltration and nanofiltration membranes have unalterable pore sizes and surface characteristics, limiting their efficiency in industrial filtration processes, and there is a need for membranes that can dynamically adjust their permeability and selectivity in response to environmental signals.
Innovation Solution
A membrane with gas-tunable pore size is developed, utilizing randomly arranged cellulose nanocrystals and CO2-responsive polymer chains grafted on their surface, which change pore size in response to CO2 and inert gases, allowing for adjustable molecular weight cut-off and flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional porous membranes are used, then the membrane structure is simple and easy to manufacture, but the pore size and surface characteristics are unalterable, limiting filtration efficiency
Solution Approach 1:
The membrane incorporates CO2-responsive polymer chains that dynamically change their conformation in response to CO2 pressure, transforming the static pore structure into a dynamic one. When CO2 pressure increases, the polymer chains collapse, opening pores; when CO2 pressure decreases, chains extend, closing pores. This dynamic behavior enables real-time adjustment of pore size and filtration efficiency without changing the physical membrane structure.
Solution Approach 2:
The invention changes the physical-chemical parameters of the membrane by introducing CO2-responsive polymer chains grafted on cellulose nanocrystals. The polymer chains undergo conformational changes (extended vs. collapsed states) in response to CO2 pressure variations, thereby changing the effective pore size parameter. This allows the same membrane to operate at different filtration levels by simply adjusting CO2 pressure.
2Adaptability or versatility
If stimuli-responsive membranes with dynamic pore adjustment are developed, then filtration efficiency and selectivity are improved, but the membrane structure and operation become more complex
Solution Approach 1:
The CO2-responsive polymer chains act as intermediary elements between the CO2 gas and the membrane pore structure. Instead of directly controlling pore openings, CO2 pressure modulates the conformation of polymer chains, which in turn control pore size. This intermediary mechanism simplifies the control system, requiring only CO2 pressure adjustment rather than complex mechanical or electrical control systems.
Solution Approach 2:
The membrane is constructed as a composite material combining cellulose nanocrystals (providing structural framework) with CO2-responsive polymer chains (providing dynamic control). This composite structure integrates the mechanical stability of cellulose with the stimulus-responsive properties of the polymer, achieving both structural integrity and dynamic pore adjustment without excessive complexity.
3Measurement precision
If the membrane uses fixed pore size for precise molecular separation, then separation precision is improved, but the membrane cannot be reused for different separation tasks requiring different pore sizes
Solution Approach 1:
The membrane enables periodic switching between different filtration modes by cyclically adjusting CO2 pressure. The polymer chains periodically transition between extended and collapsed states, allowing the membrane to alternately operate at different molecular weight cut-offs. This periodic action facilitates a single membrane to perform multiple separation tasks that would otherwise require multiple specialized membranes.
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 membrane achieves reversible and tunable pore size adjustments, enhancing filtration efficiency and operational flexibility, enabling precise separation of molecules and proteins, and facilitating easy cleaning and reuse.
Implementation Method 1
chains of CO2-responsive polymer are grafted on the surface of the cellulose nanocrystals... which change pore size in response to CO2 and inert gases
Implementation Method 2
pores are defined in the active layer by the free spaces existing between the randomly arranged cellulose nanocrystals
Data Source
AI summary
An ultrafiltration/nanofiltration membrane with gas-tunable pore size is provided. This membrane comprises an active layer arranged between two porous support layers, wherein the active layer is formed of randomly arranged cellulose nanocrystals, wherein pores are defined in the active layer by the free spaces existing between the randomly arranged cellulose nanocrystals, and wherein chains of a CO2-responsive polymer are grafted on the surface of the cellulose nanocrystals. There are also provided methods for filtering a feed using the membrane, for tuning the apparent pore size/MWCO/charge of the membrane, for cleaning the membrane, and for manufacturing the membrane.