Recently, the research team led by Academician Ma Jun from the School of Environment at our university has made significant progress in enhancing the antifouling capability of water treatment membranes. The team proposed a strategy utilizing supramolecular dynamics to strengthen a “resistance–repulsion” synergistic antifouling mechanism, overcoming two major drawbacks of conventional synergistic antifouling mechanisms—dependence on tangential flow and suppression of membrane flux. The related research, entitled “Supramolecular dynamics-enhanced synergistic antifouling mechanisms for enhanced membrane antifouling and permeability,” was published in Nature Communications. This study provides a new strategy for achieving low-energy, high-stability operation of water treatment membranes and shows great potential for applications in municipal wastewater and industrial effluent treatment.
The “resistance–repulsion” synergistic antifouling mechanism, based on hydrophilic–low surface energy heterogeneous microdomains, holds excellent potential for improving membrane stability and lifespan. Hydrophilic microdomains form hydration barriers by binding with water molecules, hindering the migration of foulants toward the membrane surface. Meanwhile, low surface energy microdomains reduce the interaction between foulants and the membrane surface, promoting foulant detachment. However, this antifouling mechanism faces two inherent limitations. First, during transmembrane water transport, foulants tend to be compressed onto the membrane surface, requiring high tangential flow to promote their removal. Second, low surface energy components tend to aggregate and adhere to the membrane surface during membrane formation, blocking water channels and limiting flux enhancement.
To address these challenges, the team proposed constructing an antifouling layer on the membrane surface using supramolecules instead of conventional polymers. The supramolecular structure, composed of polydimethylsiloxane (PDMS) and cyclodextrin (CD), forms a polyrotaxane architecture. PDMS is a linear macromolecule with low surface energy, while CD is a hydrophilic cyclic small molecule. The CD–PDMS polyrotaxane exhibits a “chain-through-ring” structure, where CDs can slide, rotate, and vibrate along the PDMS chain, creating dynamically heterogeneous hydrophilic–low surface energy microdomains. This dynamic configuration renders the contact between foulants and the membrane surface unstable, and the Brownian motion of CDs enables effective foulant detachment even under low tangential flow or static conditions. Additionally, this structure prevents aggregation of low surface energy components and promotes water transport via hydrogen bonding interactions.
The study revealed a cascade relationship among CD type, CD/PDMS molar ratio, CD–PDMS polyrotaxane dynamics, and the overall membrane performance, identifying the optimal antifouling layer structure. Due to its larger cavity and higher flexibility, γ-CD/PDMS polyrotaxane exhibits stronger dynamics than β-CD/PDMS polyrotaxane. When the molar ratio of CD to PDMS repeat units ranges from 0.27 to 0.40 (where 0.67 corresponds to complete CD coverage of PDMS), the supramolecular dynamicity reaches its maximum, with the product of single CD mobility and CD quantity attaining the highest value. Experimental results showed that the membrane’s overall performance peaks when the supramolecular antifouling layer exhibits the strongest dynamicity, achieving a permeability of 500 LMH·bar⁻¹ at 20 °C, BSA flux decline of 14.2%, and flux recovery of 99.7%. The excellent antifouling performance was also demonstrated against various foulants including yeast cells, humic acid, sodium alginate, and emulsified oil, and during 72-hour cross-flow experiments using Songhua River water, municipal wastewater, and Lurgi coal gasification wastewater, the membrane exhibited outstanding stability with only 3–7% flux decline per backwashing cycle (4 h) and nearly 100% flux recovery after chemical cleaning. Control experiments confirmed that supramolecular dynamics are the key factor for flux enhancement, while AFM force measurements and micro-adsorption experiments further validated the multifaceted role of supramolecular dynamics in strengthening membrane antifouling performance. The combination of experimental and theoretical results provides new insights and strategies for advancing antifouling capabilities of water treatment membranes.
Harbin Institute of Technology is the sole corresponding institution for this paper. Associate Professor Mingrui He from the School of Environment is the first author, with Professor Dongwei Lü and Academician Jun Ma serving as corresponding authors. This research was supported by the National Key R&D Program for Young Scientists, the National Natural Science Foundation of China (NSFC) Young Scientist Fund, the China Postdoctoral Science Foundation Special Support Program, and the State Key Laboratory of Urban-rural Water Resource and Environment.
Paper link: doi.org/10.1038/s41467-025-62231-w
