Water droplet on patterned membrane surface

The Water's Edge: How Membrane Properties Shape Contact Angle and Why It Matters

Reese Marlowe in Science & Nature November 2025 • 4 min read.

"Unveiling the connection between membrane characteristics and contact angle for better material design"

In the realm of material science, the contact angle holds significant sway, especially when it comes to membranes. This angle, formed where a liquid meets a solid surface, isn't just a visual curiosity; it's a vital indicator of a membrane's hydrophilicity—its affinity for water—and how prone it is to fouling, the undesirable accumulation of deposits that can hamper performance.

Scientists have long sought ways to predict this angle, employing methods like interfacial tension calculations and thermodynamic modeling. However, these approaches often demand detailed knowledge of a material's properties, information that may be scarce, especially for cutting-edge materials. Recent studies suggest that fundamental membrane characteristics, such as pure water permeation (PWP), porosity, and pore size, also influence the contact angle. But how exactly do these factors stack up against each other?

New research aims to rank the impact of PWP, pore size, and porosity on a membrane's contact angle. By understanding these relationships, researchers hope to develop models that can estimate contact angle based on easily accessible membrane properties, paving the way for the design of more efficient and durable materials.

Decoding Membrane Properties: What Affects the Angle?

Water droplet on patterned membrane surface

The study focuses on polyethersulfone (PES) membranes, a popular choice in various applications due to their robustness and chemical resistance. Data from approximately 90 different PES membranes were gathered from existing research, encompassing a range of PWP values, pore sizes, porosities, and contact angles. These data points were then subjected to rigorous analysis using ANOVA (analysis of variance) and Taguchi methods, statistical techniques designed to tease out the relative importance of each factor.

One key consideration was the mode of filtration used to characterize the membranes: dead-end (DE) or cross-flow (CF) filtration. In DE filtration, water is forced directly through the membrane, while in CF filtration, the water flows parallel to the surface. Since filtration mode can affect the measured flux (the rate at which water passes through the membrane), the analysis was carefully controlled to account for these differences.

Here’s a simplified view of the factors and levels considered:

Porosity: Ranges from 0.112 to 0.879
PWP (Pure Water Permeation): From 3.30 L/m²h to over 198.00 L/m²h
Pore Size: From 1.07 nm to over 50.00 nm

The Taguchi method, a statistical approach for optimizing processes, was used to design a series of nine experiments, each varying the levels of PWP, pore size, and porosity. By analyzing the results of these experiments, the researchers could rank the factors according to their influence on the contact angle.

The Verdict: Which Property Reigns Supreme?

The analyses revealed that porosity and pore size exert a more significant influence on the contact angle than PWP. This suggests that the surface characteristics of the membrane play a dominant role in determining how water interacts with the material. While PWP is still an important factor, as it indirectly reflects the membrane's hydrophilicity, porosity and pore size appear to be the primary drivers of contact angle behavior. These findings pave the way for the development of more accurate models for predicting contact angle based on fundamental membrane properties, accelerating the design and optimization of advanced membrane materials.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1063/1.5055437, Alternate LINK

Title: Effect Of Membrane Properties On Contact Angle

Journal: AIP Conference Proceedings

Publisher: Author(s)

Authors: Mieowkee Chan, Sokchoo Ng

Published: 2018-01-01

Everything You Need To Know

Why is understanding the contact angle important in the context of membranes?

The contact angle is crucial because it indicates a membrane's hydrophilicity, which is its affinity for water. It also reveals how prone the membrane is to fouling, which is the accumulation of deposits that negatively affect its performance. Understanding the contact angle helps in designing more efficient and durable membrane materials.

What methods have researchers used to predict contact angle, and what are the limitations of these approaches?

Researchers use methods like interfacial tension calculations and thermodynamic modeling to predict the contact angle. However, these methods require detailed knowledge of the material's properties, which may not always be available. Recent studies explore using fundamental membrane characteristics such as pure water permeation (PWP), porosity, and pore size to estimate the contact angle.

What type of membranes were the focus of the study, and why were they chosen?

The study focused on polyethersulfone (PES) membranes, which are widely used due to their robustness and chemical resistance. Researchers analyzed data from approximately 90 different PES membranes, considering a range of pure water permeation (PWP) values, pore sizes, porosities, and contact angles. They used ANOVA and Taguchi methods to determine the relative importance of each factor.

Why was the mode of filtration an important consideration in the research on membrane properties and contact angle?

The mode of filtration, whether dead-end (DE) or cross-flow (CF), was a key consideration because it affects the measured flux, or the rate at which water passes through the membrane. In DE filtration, water is forced directly through the membrane, while in CF filtration, water flows parallel to the surface. The analysis was carefully controlled to account for these differences.

What did the research reveal about the relative influence of pure water permeation (PWP), porosity, and pore size on the contact angle of membranes, and what are the implications of these findings?

The research found that porosity and pore size have a more significant influence on the contact angle than pure water permeation (PWP). This suggests that the surface characteristics of the membrane are more important in determining how water interacts with the material. While PWP is still relevant, porosity and pore size are the primary factors driving contact angle behavior, aiding in developing accurate models for predicting contact angle and optimizing membrane materials.