Self-Lubricating Polymer Surfaces for Liquid Repellency

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Solution Overview

Problem

Current slippery surface technologies face challenges in maintaining slipperiness over large areas efficiently and for extended periods, especially under dynamic flow conditions, and in preventing adhesion of liquids and microorganisms, due to issues like air instability under pressure and irreversible defects from mechanical damage.

Innovation Solution

A system comprising a flowable precursor composition of a prepolymer and a curing agent, combined with a lubricating liquid that forms a stable, non-adhering, self-cleaning, and low-friction surface, where the polymer and lubricating liquid form a composite overlayer with a predetermined swelling ratio, providing a slippery layer that self-replenishes and maintains its properties despite physical damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If textured surfaces are used to create water-repellent properties, then liquid repellency is improved, but mechanical durability deteriorates due to irreversible defects from mechanical damage

Engineering Contradiction:
Improveliquid repellencyVSAvoidmechanical durability
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent transitions from textured surfaces to smooth surfaces by changing the topographical parameter, while maintaining liquid repellency through chemical composition changes (fluorinated polymer blend). This eliminates mechanical durability issues associated with textured surfaces.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite material system consisting of a fluorinated polymer blend (e.g., polytetrafluoroethylene and polyvinylidene fluoride) that combines the low surface energy properties of fluorinated polymers with enhanced mechanical durability, achieving both liquid repellency and mechanical robustness on smooth surfaces.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If air is trapped within surface textures to support liquids, then liquid mobility is improved, but stability under pressure deteriorates

Engineering Contradiction:
Improveliquid mobilityVSAvoidair cushion stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent extracts and eliminates the air cushion component from the liquid support mechanism, replacing it with a solid polymer surface that directly supports liquids through its chemical composition (low surface energy fluorinated polymer blend) rather than through trapped air, thereby achieving pressure stability.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If complex topographical features are created on surfaces, then liquid repellency is enhanced, but foreign material adhesion worsens

Engineering Contradiction:
Improveliquid repellencyVSAvoidforeign material adhesion
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the topographical parameter from complex to smooth, and compensates for liquid repellency by adjusting the chemical composition parameter (using fluorinated polymer blend with low surface energy), thereby preventing foreign material adhesion while maintaining repellency.

Inventive Principle:
Principle #35Parameter changes

4Reliability

If slippery coatings are applied to large surfaces, then liquid repellency is improved, but application efficiency deteriorates

Engineering Contradiction:
Improveliquid repellencyVSAvoidapplication efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The fluorinated polymer blend coating provides multiple functions simultaneously: liquid repellency, mechanical durability, and ease of application. The coating can be applied using conventional methods (spray, dip, brush) and cures to form a robust, slippery surface, eliminating the need for specialized application processes.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 solution achieves a significant reduction in biofilm formation and adhesion of foreign materials, maintaining a slippery surface for extended periods with reduced contact angle hysteresis and enhanced self-healing properties, effectively addressing the limitations of existing technologies.

Implementation Method 1

the polymer material and the lubricating liquid have an affinity for each other such that the polymer material swells to absorb the lubricating liquid in an amount sufficient to form the lubricating layer

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

a lubricating layer, which creates a defect-free slippery surface that can reduce contact angle hysteresis and adhesion of external matter

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP2872572B1Slippery self-lubricating polymer surfaces
Publication Date: 2024.06.19 PRESIDENT & FELLOWS OF HARVARD COLLEGE
  • EP2872572B1 patent drawingFigure 1A~1C
  • EP2872572B1 patent drawingFigure 2A
  • EP2872572B1 patent drawingFigure 2B~2C

AI summary

The present disclosure describes a strategy to create self-healing, slippery self- lubricating polymers. Lubricating liquids with affinities to polymers can be utilized to get absorbed within the polymer and form a lubricant layer (of the lubricating liquid) on the polymer. The lubricant layer can repel a wide range of materials, including simple and complex fluids (water, hydrocarbons, crude oil and bodily fluids), restore liquid-repellency after physical damage, and resist ice, microorganisms and insects adhesion. Some exemplary applications where self-lubricating polymers will be useful include energy-efficient, friction- reduction fluid handling and transportation, medical devices, anti-icing, optical sensing,and as self-cleaning, and anti-fouling materials operating in extreme environments.