Smart Self-Cleaning Membrane via the Blending of an Upper Critical Solution Temperature Diblock Copolymer with PVDF

Abstract

Poly­(2,2,2-trifluoroethyl methacrylate)-b-poly­(imidazoled glycidyl methacrylate-co-diethylene glycol methyl ether methacrylate) (PTFEMA-b-P­(iGMA-co-MEO2MA)) containing an upper critical solution temperature (UCST) polymer chain was prepared and blended with poly­(vinylidene fluoride) (PVDF) to produce a thermoresponsive membrane with smart self-cleaning performance. The successful preparation of the membrane was demonstrated by attenuated total reflection–Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy characterization. The membrane shows UCST performance, and its flux changes with the filtrate temperature as the UCST polymer chain stretches out and contracts in response to various temperatures. In addition, the UCST polymer chain can disrupt the foulant and push it away from the membrane when the temperature is above the UCST and thus enables membranes to exhibit a smart self-cleaning behavior. To the best of our knowledge, this work is the first report of a smart self-cleaning membrane based on the blending of a diblock copolymer containing a UCST polymer chain with PVDF.

Temperature-Responsive Polymer Brush Coatings for Advanced Biomedical Applications

“…When the temperature increases above the LCST, the macromolecules collapse and transform into collapsed hydrophobic globules weakly miscible with the environment [ 37 ]. This scenario is opposite for polymers with UCST, where the macromolecular chains are in the collapsed hydrophobic state below UCST and in the extended hydrophilic chain conformation above UCST [ 33 , 38 , 39 , 40 , 41 , 42 ]. In polymer chemistry, the phenomenon of the LCST is related to the systems based on polymer-solvent mixtures that are miscible below a given critical temperature and turn to two-phase unmixed systems above this critical temperature.…”

Permeate Flux Control of a Conductive Membrane through a PEDOT Redox Switch

“…Smart filtration membranes, where permeability can be controlled for advanced functions, such as size-selective rejection and permeate flux control, have recently been of increased research interest. − In many cases, permeability controls have been based on grafting pH- and temperature-responsive polymers on the membrane surfaces. − The reversible protonation of a polyelectrolyte with a weak acid and base provides a switchable brush-swelling mechanism through the charge repulsion between adjacent charges on the polymer backbones upon pH change. , The temperature-switchable polymer brush mechanism is mainly limited to poly­( N -isopropyl acrylamide), ,− which exhibits an upper critical temperature above 32 °C. Although there have been a number of literature reports on the use of these polymer brushes as a pH and temperature switch for permeability control, − the implementation of such a switching system could be difficult when the filtration system requires an optimum or controlled pH or temperature range for the operation. For instance, in food and beverage applications, heat treatment or pH adjustment may result in quality issues such as alternating organoleptic properties and/or appearance, as well as affecting the filtration process − (e.g., kinematic viscosity of a liquid decreases with a higher temperature).…”