Fluoropolymer Copolymerization for Adhesion and Hydrophilicity

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Solution Overview

Problem

Fluoropolymers face challenges in adding functional monomer units directly into their polymer backbone due to the aggressive nature of fluorine-containing free radicals, limiting their applications by preventing adhesion, cross-linking, and hydrophilicity.

Innovation Solution

A random copolymer of 75 to 99.95 mole percent fluoromonomers and 0.05 to 25 mole percent vinyl ester monomers, with at least 40 mole percent vinyl ester units as single units between fluoromonomer units, formed through a starve-feed process to ensure uniform distribution and improved properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If functional monomer units are added directly into the fluoropolymer backbone, then adhesion and hydrophilicity are improved, but the aggressive fluorine-containing free radicals prevent uniform distribution and random incorporation

Engineering Contradiction:

Improveadhesion and hydrophilicityVSAvoiduniform distribution of functional monomers

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-forming fluoropolymer particles with controlled radical sites, then introducing vinyl ester monomers in a second polymerization step. This two-stage approach allows functional monomers to be incorporated uniformly without the aggressive fluorine radicals present from the start, resolving the contradiction between adhesion improvement and uniform distribution.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the polymerization process into two distinct stages: first forming fluoropolymer particles, then adding vinyl ester monomers. This segmentation separates the aggressive fluorine radical generation from the functional monomer incorporation, enabling both improved adhesion and uniform distribution of functional units.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If vinyl ester monomers are incorporated into fluoropolymer backbone, then functional groups are added for cross-linking and chemical modification, but the fluorine radicals make direct copolymerization difficult

Engineering Contradiction:

Improvecross-linking and chemical modification capabilityVSAvoiddirect copolymerization process

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent uses preliminary action by completing fluoropolymer formation first, then adding vinyl ester monomers in a subsequent step. This allows functional groups to be introduced without the complicating presence of fluorine radicals during the functional monomer polymerization, making the manufacturing process easier while achieving cross-linking capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary approach by using a two-stage polymerization process where the first stage creates a controlled environment for the second stage. This intermediary step mediates between the aggressive fluorine radicals and the sensitive vinyl ester monomers, enabling successful copolymerization that would be difficult in a single step.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If post-reaction grafting is used to add functionality, then functional groups are introduced, but the process is complex and does not achieve uniform distribution

Engineering Contradiction:

Improvefunctional groupsVSAvoidpost-reaction grafting process

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by incorporating functional monomers during the polymerization process itself rather than through post-reaction grafting. This eliminates the need for separate grafting steps and achieves uniform distribution from the beginning, reducing process complexity while maintaining functional group introduction.

Inventive Principle:

Principle #10Preliminary action

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 resulting copolymer exhibits enhanced adhesion, hydrophilicity, and chemical resistance, making it suitable for applications like hydrophilic membranes and electrodes, with improved shelf stability and water resistance.

Implementation Method 1

due to the aggressive nature of the fluorine-containing free radicals

Methodology Applied

Scientific EffectFree radical polymerization:

Implementation Method 2

Methodology Applied

Scientific EffectStarve-feed process:

Data Source

PatentUS10570231B2Fluoropolymers

Publication Date: 2020.02.25 ARKEMA INC

AI summary

The invention relates to novel linear, semi-crystalline fluoropolymers containing 0.5 to 25 mole percent of at least one vinyl ester monomer unit. At least 40 mole percent of the vinyl ester monomer units are present in the copolymer as single monomer units (not diads or triads or greater) between two fluoromonomer units. The invention also relates to a process for forming the fluoromonomers/vinyl ester copolymer. The fluoropolymer of the invention may be used in applications benefiting from a functional fluoropolymers including as a binder or coating in batteries, or for use in forming hydrophilic membranes and hollow fibers.