Bacteria-Resistant, Transparent, Free-Standing Films Prepared from Complex Coacervates

Abstract

We report the fabrication, properties, and bacteria-resistance of polyelectrolyte complex (PEC) coatings and free-standing films. Poly(4-styrenesulfonic acid), poly(diallyldimethyl-ammonium chloride), and salt were spin-coated into PEC films. After thermal annealing in a humid environment, highly transparent, mechanically strong, and chemically robust films were formed. Notably, we demonstrate that PEC coatings significantly reduce the attachment of Escherichia coli K12 without killing the micro-organisms. We suggest that forming bacteria-resistant surface coatings from commercially available polymers holds the potential for use across a wide range of applications including high-touch surfaces in medical settings.

Recent progress in the science of complex coacervation

“…In particular, a seminal report by Wang and Schlenoff demonstrated that solid precipitates and liquid coacervates could exist along a continuum of salt concentration ( Figure 10). 50 This idea of salt-driven plasticization, or 'salo- plasticity' has opened up a tremendous range of opportunities for using salt to process polyelectrolyte complex materials as liquid coacervates, and then solidify the materials by the removal of salt, and a range of accounts describing ultracentrifuged [190][191][192][193] or extruded materials, 194 spin-coated films, 195,196 3D printed structures, 197 and electrospun fibers 65,198,199 have been reported.…”

Polyelectrolyte Complex Membranes via Salinity Change Induced Aqueous Phase Separation

“… 31 − 35 Porous saloplastic materials are obtained by centrifugation 31 , 36 and electrospinning 37 of coacervate phases or by desalting a homogeneous PE solution in between semipermeable membranes. 38 In addition, doped PECs can be extruded to obtain dense materials in various shapes (tape, tube, rod, and fiber) 32 , 33 or spin-coated, 34 , 39 cast, 40 , 41 or pressed in between templates 42 , 43 to obtain transparent films. Moreover, some of the saloplastics show self-healing behavior which can operate under room temperature and tuned by type of salt.…”

Polyelectrolytes as Building Blocks for Next-Generation Membranes with Advanced Functionalities

“… 211 Using salt as a plasticizer allowed the PECs to be formed in different shapes and sizes, proving that PECs are actually processable just like thermoplastics. 33 , 212 − 214 This accelerated the research on saloplastic materials, and many papers have been published on advanced functional saloplastics with self-healing, 215 − 217 shape recovery, 218 patternability, 219 antifouling, 18 gas barrier, 220 and chemical stability 212 features. Additionally, incorporation of PECs with other kinds of materials, such as nanoparticles, is also demonstrated indicating it is possible to have materials with even more advanced functions.…”

“…The literature on this is predominantly on copolymer membranes which are prepared with NIPS. There are a few studies on antifouling saloplastic material, 18 and to our knowledge, the work of Willott et al. is the only study that investigates stimuli-responsive and self-cleaning functions of homopolymer free-standing membranes 251 prepared with APS.…”

“…On the other hand, hydrophilic polymers are less prone to foul and easier to clean. 18 Hydrophilicity is also required for applications such as pervaporation 19 (especially for dehydration of organic/aqueous mixtures) or oil–water separations. 20 PEs are highly desired for these kinds of applications, not only because of their hydrophilic nature, but also due to the possibility to tune their features (e.g., swelling and charge density).…”