Blood-Contact Separation Membrane Coating for Stable Filtration
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Solution Overview
Problem
Existing separation membranes used in medical and water treatment applications suffer from protein and platelet adherence, leading to performance deterioration over time, especially when in contact with biological components like blood, and existing methods to enhance hydrophilicity either fail to form a coating or result in reduced water removal performance.
Innovation Solution
A separation membrane module comprising a hydrophobic polymer, a hydrophilic polymer, and a copolymer with a hydrophilic and hydrophobic unit, specifically a propyl methacrylate unit, which suppresses adherence of platelets and proteins while maintaining high albumin sieving coefficients and filtration performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrophilic polymer such as polyvinylpyrrolidone is added to the membrane forming dope solution to impart hydrophilicity to the membrane surface, then the adherence of platelets or proteins is suppressed, but the coating layer cannot be formed due to weak interaction between the hydrophilic polymer and the hydrophobic base polymer
Solution Approach 1:
The patent introduces a copolymer comprising both hydrophilic units (e.g., vinylpyrrolidone) and hydrophobic units (e.g., vinyl acetate) as an intermediary substance. The hydrophobic units interact strongly with the hydrophobic base polymer through hydrophobic interaction, while the hydrophilic units provide the desired anti-adherence properties. This copolymer acts as a bridge that connects the hydrophobic membrane base with the required hydrophilic surface properties, enabling effective coating layer formation.
Solution Approach 2:
The patent uses a composite copolymer material that combines both hydrophilic and hydrophobic characteristics in a single polymer chain. This composite structure allows the polymer to simultaneously interact with the hydrophobic membrane base and provide hydrophilic surface properties, resolving the contradiction between adhesion to the base and suppression of protein/platelet adherence.
2Manufacturing precision
If a vinylpyrrolidone/vinyl acetate copolymer is used to efficiently form a coating layer on the membrane surface through hydrophobic interaction, then the introduction efficiency is increased, but no structural design suitable for suppressing the adherence of platelets or proteins is considered and performance deteriorates over time
Solution Approach 1:
The patent applies local quality by concentrating the hydrophilic units (vinylpyrrolidone) at the membrane surface through controlled copolymerization and processing conditions. This creates a surface-enriched hydrophilic layer that provides anti-adherence properties where needed, while the bulk membrane maintains its structural integrity and hydrophobic interaction capabilities. The local concentration of hydrophilic groups at the surface ensures both effective coating formation and long-term performance stability.
3Reliability
If the introduction amount of copolymer is increased to suppress the adherence of platelets or proteins, then the adherence is reduced, but the water removal performance is deteriorated and the amount of the eluate is increased
Solution Approach 1:
The patent optimizes the parameters of the copolymer including the molar ratio of hydrophilic to hydrophobic units, molecular weight, and concentration in the dope solution. By carefully controlling these parameters, the patent achieves the minimum effective concentration of hydrophilic groups needed to suppress protein/platelet adherence without excessive amounts that would block pores and reduce water permeability. This parameter optimization balances anti-adherence performance with water removal efficiency.
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 module effectively reduces adherence of platelets and proteins, ensuring stable performance over extended use, with a retention rate of albumin sieving coefficient of 86% or more, suitable for blood purification and water treatment applications.
Implementation Method 1
a vinylpyrrolidone/vinyl acetate copolymer, which is a commercially available polymer, is used... a vinyl acetate unit interacts with a hydrophobic base, whereby the introduction efficiency of the copolymer is increased
Implementation Method 2
the separation membrane module having a retention rate of an albumin sieving coefficient of 86% or more... suitable for blood purification
Data Source
Figure 1~2
Figure 3~4
AI summary
The purpose of the present invention is to provide a separation membrane module of which the performance does not deteriorate even when coming into contact with a biological component such as blood, which can be used for a prolonged period, which has a superior removal performance against moisture and the like, and which produces less eluates. The present invention is provided with a separation membrane comprising a hydrophobic polymer, a hydrophilic polymer, and polymer A, wherein: polymer A is a copolymer that comprises a hydrophilic unit and a hydrophobic unit and that has an alkyl group having 2-20 carbon atoms at a side-chain terminal of the hydrophilic unit; and when two liters of bovine blood containing 50 U/ml of heparin and having a hematocrit value of 30 vol% and a total protein concentration of 6-7 g/dl is circulated at a flow rate of 100 ml/min at 37°C so as to result in a filtration flow rate of 10 ml/(min·m2), the albumin sieving coefficient as of 60 minutes after the initiation of the circulation retains at least 86% of the albumin sieving coefficient as of 10 minutes after the initiation of the circulation.