To enhance the hydrophilicity of polymeric microfiltration membranes, the key is to reduce their surface contact angle (a contact angle θ < 70° is considered hydrophilic) and improve surface wettability.

To enhance the hydrophilicity of polymeric microfiltration membranes, the key is to reduce their surface contact angle (a contact angle θ < 70° is considered hydrophilic) and improve surface wettability. The mainstream approaches include:

1. Surface grafting modification
Hydrophilic polymer chains, such as polyacrylic acid (PAA) or polyvinyl alcohol (PVA), are grafted onto the membrane surface via chemical bonds. These polymers utilize their polar functional groups—such as hydroxyl and carboxyl groups—to form hydrogen-bonding networks with water. For example, grafting hydrophilic microgels onto a PVDF membrane can create an interpenetrating network structure, significantly enhancing both antifouling performance and mechanical strength.

2. Surface Coating Technology
Hydrophilic materials (such as nanocellulose CNF) are coated onto the membrane surface via spray coating or roll-to-roll processes. For example, after being coated with CNF, PES membranes exhibit a water permeation rate of 80–100 LMH/MPa and a rejection rate of >90% for negatively charged molecules. Poly-silazane coatings can also achieve hydrophilic effects by controlling the crosslinking density.

3. Surface Chemical Modification
Hydrophilic functional groups are introduced onto the membrane surface through reactions such as silanization. For example, a polysilazane coating modified by fluorination can simultaneously provide both hydrophobicity and thermal stability.

4. Other physical modifications
These include plasma treatment and corona discharge, which modify surface energy by introducing polar functional groups.

After modification, the enhancement of hydrophilicity must be verified through contact angle testing (e.g., according to GB/T 30447 standard), and its chemical stability (e.g., flux decline <10% after immersion in solutions with pH ranging from 1 to 13) and anti-fouling performance (e.g., BSA adsorption study) must also be evaluated.

Do you need a comparison table of hydrophilic modification methods? We can help you quickly identify the most suitable technical approach for your membrane material.