Substituted Benzamide Monomer for Polyamide Membrane Salt Rejection

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Solution Overview

Problem

Current composite polyamide membranes for fluid separations, such as reverse osmosis and nanofiltration, face limitations in rejecting certain salts and organic molecules, necessitating the development of new monomers to enhance membrane performance.

Innovation Solution

A method for forming composite polyamide membranes involves applying a polar solution of polyfunctional amine monomers and a non-polar solution of polyfunctional acyl halide monomers to a porous support, with the inclusion of a substituted benzamide monomer in the non-polar solution, represented by specific chemical formulas, to interfacially polymerize a thin film polyamide layer, improving membrane selectivity and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional polyfunctional acyl halide monomers are used in interfacial polycondensation, then the membrane can be formed with standard polyamide structure, but the rejection of certain salts and organic molecules is insufficient

Engineering Contradiction:

Improverejection of salts and organic moleculesVSAvoidmembrane selectivity for different solutes

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent modifies the acyl halide monomer structure by introducing electron-withdrawing groups (such as fluorine atoms at positions 2 and 6 of the benzoyl chloride ring). This structural parameter change alters the electronic properties and steric characteristics of the monomer, which in turn changes the polyamide membrane's pore structure and surface properties, leading to improved rejection of specific salts and organic molecules while maintaining formation capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite monomer structure combining benzoyl chloride core with electron-withdrawing substituents (e.g., fluorine atoms). This creates a functionally composite monomer that provides both the essential polyamide-forming acyl halide functionality and additional selectivity-enhancing electronic effects, resulting in membranes with superior discrimination between solutes and solvents

Inventive Principle:

Principle #40Composite materials

2Reliability

If electron-withdrawing groups are added to the acyl halide monomer, then membrane selectivity is improved, but the risk of chlorination increases

Engineering Contradiction:

Improvemembrane selectivityVSAvoidchlorination of the membrane

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent carefully selects and positions electron-withdrawing groups (such as fluorine at positions 2 and 6) on the acyl halide monomer. This specific structural modification enhances membrane selectivity through altered electronic properties while the positioning and type of substituents are chosen to minimize side reactions that lead to chlorination, thus balancing selectivity improvement with harmful effect reduction

Inventive Principle:

Principle #35Parameter changes

3Reliability

If new substituted benzamide monomers are synthesized and used, then membrane performance in fluid separations is enhanced, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improvefluid separation performanceVSAvoidmonomer synthesis and coating process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces substituted benzamide monomers with specific structural parameters (electron-withdrawing groups at defined positions) that enhance fluid separation performance. While the monomer structure is more complex than conventional acyl halides, the substitution pattern is designed to be synthetically accessible and the monomer maintains compatibility with existing interfacial polycondensation processes, thus improving performance while controlling the increase in manufacturing complexity

Inventive Principle:

Principle #35Parameter changes

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 results in membranes that effectively reject a high percentage of salts and organic molecules, demonstrating improved performance in fluid separations by incorporating the substituted benzamide monomer, which enhances the membrane's ability to discriminate between solutes and solvents.

Implementation Method 1

interfacially polymerizing the monomers to form a thin film polyamide layer

Methodology Applied

Scientific EffectInterfacial polycondensation: Chemical Bonding

Data Source

PatentUS9895666B2Composite polyamide membrane made using substituted benzamide monomer

Publication Date: 2018.02.20 DDP SPECIALTY ELECTRONICS MATERIALS US LLC

AI summary

A method for making a composite polyamide membrane comprising a porous support and a thin film polyamide layer, wherein the method includes the steps of applying a polar solution comprising a polyfunctional amine monomer and a non-polar solution comprising a polyfunctional acyl halide monomer to a surface of a porous support and interfacially polymerizing the monomers to form a thin film polyamide layer. The method is characterized by including a substituted benzamide monomer within the non-polar solution.