PDMS Grafted Surface for Liquid Repellency and Durability
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Solution Overview
Problem
Existing surface treatments that create superhydrophobic or superoleophobic surfaces often suffer from durability issues due to loss of air or liquid lubricant and topography damage, leading to a need for treatments that can effectively repel liquids for extended durations.
Innovation Solution
A method involving the hydroxylation of a substrate surface followed by exposure to a polydimethylsiloxane (PDMS) oligomer, resulting in a grafted layer of PDMS polymers covalently bonded to the surface, which provides a semi-liquid surface (SLS) with enhanced liquid repellency and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If superhydrophobic or superoleophobic surfaces are formed using air lubricant, then liquid repellency is improved, but durability deteriorates due to loss of air lubricant or topography damage
Solution Approach 1:
The patent introduces a liquid lubricant as an intermediary substance that infuses the surface topography to create liquid-infused surfaces. This liquid lubricant layer mediates between the solid surface and external liquids, providing enhanced liquid repellency while the covalently bonded PDMS polymer layer ensures durability by preventing lubricant loss and resisting topography damage.
Solution Approach 2:
The patent creates a composite surface structure combining a solid substrate with surface topography and a liquid lubricant layer. The liquid lubricant and solid surface work together synergistically to provide both liquid repellency and durability, overcoming the limitations of air lubricant-based surfaces.
2Reliability
If liquid-infused surfaces are created using liquid lubricant, then liquid repellency is improved, but durability deteriorates due to lubricant loss
Solution Approach 1:
The liquid lubricant acts as an intermediary that reduces direct contact between external liquids and the solid surface. The covalently bonded PDMS polymer layer serves as a retaining structure that prevents lubricant loss, allowing the liquid lubricant to maintain its function without depleting over time.
Solution Approach 2:
The PDMS polymer layer forms a flexible, covalently bonded thin film that conforms to the surface topography and traps the liquid lubricant within the surface structures. This flexible film prevents lubricant loss while maintaining the liquid-infused surface's repellency properties.
3Duration of action of stationary object
If surface topography is damaged, then durability deteriorates, but liquid repellency may be maintained through re-treatment
Solution Approach 1:
The PDMS polymer layer is covalently bonded to the surface in advance, creating a durable protective layer before any potential damage occurs. This preliminary bonding ensures that even if surface topography is damaged, the polymer layer remains intact and can retain liquid lubricant, eliminating the need for re-treatment.
Solution Approach 2:
The covalently bonded PDMS polymer layer serves as an intermediary protective barrier between the solid substrate and external environmental factors. This intermediate layer prevents direct damage to the surface topography and retains liquid lubricant, ensuring long-term durability without requiring re-treatment.
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 treated surfaces exhibit excellent liquid repellency and durability, maintaining performance under harsh conditions such as high temperature, abrasion, and adhesion tests, outperforming traditional liquid-infused surfaces and superhydrophobic surfaces in fog harvesting and self-cleaning applications.
Implementation Method 1
The R3 of the PDMS oligomer undergoes hydrolysis such that one terminal Si atom of the PDMS oligomer is covalently bonded to the hydroxylated surface
Implementation Method 2
one terminal Si atom of the PDMS oligomer is covalently bonded to the hydroxylated surface by a condensation reaction
Data Source
AI summary
A method including providing a substrate having a surface, the surface is hydroxylated and exposing the hydroxylated surface of the substrate to a PDMS oligomer. The PDMS oligomer has a formula of: R1—Si(CH3)2—(O—Si(CH3)2—)n—O—Si(CH3)2—R2 where at least one of R1 or R2 includes: —(CH2)m—R3, R3=one of —Cl, —O—(CH2)xH, —SiCl3, or —Si(O—(CH2)xH)3, x=0 to 10, m=0 to 10, n=10 to 500. R3 undergoes hydrolysis such that one terminal Si atom of the PDMS oligomer is covalently bonded to the hydroxylated surface by a condensation reaction to form a grafted layer of PDMS polymers on the surface. An article including a substrate having a surface with a grafted layer of PDMS polymers thereon, each of the PDMS polymers have a formula of: -Q1-Si(CH3)2—(O—Si(CH3)2—)n—O—Si(CH3)2-Q2 where Q1=—O— or —O—(CH2)m—O—, Q2=-(-Q1-Si(CH3)2—(O—Si(CH3)2—)n—O—Si(CH3)2—)p-Q3, Q3=—OH, —(CH2)m—OH, —Si(OH)3, or —(CH2)m—Si(OH)3, m=0 to 10, n=10 to 500, p=0 to 500, Q1=end of the PDMS polymer covalently bonded to the surface.