Here, it was aimed to modify the surface of NF90 with layer by layer (LbL) blended poly(allylamine hydrochloride) (PAH)‐chitosan (CHI) and poly(acrylic acid) (PAA) with/without functionalized multiwalled carbon nanotube (fMWCNT) for reverse‐osmosis applications. Using Quartz Crystal Microbalance Dissipation monitoring, it was observed that PAH‐CHI/PAA LbL films grew linearly after a few bilayers and no LbL film degradation occurred during synthetic seawater treatment. Thermal degradation of all LbL blended membranes was similar. NF90 had a heterogeneous surface while the surface of LbL blend membranes exhibited some agglomerations due to the polyelectrolyte (PE) complex formation and fibrillary appearance depending on the use of fMWCNT. [(PAH50‐CHI50/(PAA‐fMWCNT)]30 indicated the highest flux with 14.5 L m2 h−1 at 40 bar. The sodium and chlorine ion rejections were 75% and 87%, respectively, for the same membrane. The use of fMWCNT led to a significant enhancement in flux with a slight decay in ion rejections. On the other hand, chlorine ion rejection of [(PAH50‐CHI50/(PAA‐fMWCNT)]30 decreased by 25% at 40 bar while 60 and 90 bilayers of [(PAH50‐CHI50/(PAA‐fMWCNT)] disintegrated after NaOCl treatment. Briefly, the flux and ion rejections of the LbL blended membranes can be controlled depending on the use of fMWCNT and different PE couples without multilayer decomposition against synthetic seawater. POLYM. ENG. SCI., 60: 341–351, 2019. © 2019 Society of Plastics Engineers

Preparation and characterization of a series of polyurea (PU) coatings and their influences on layered composite materials based on rebonded polyurethane (PUr) for floor application are described in terms of the raw materials, formulation, and application performance. While PU coatings show almost the same FTIR peaks, thermogravimetric analyses results reveal that thermal stabilities of the PU coatings are slightly enhanced with the use of trifunctional polyamine compound and one step degradation takes place beyond 300 C. All PU coatings have very dense, smooth, and bubble-free surfaces whereas the cross-sectional SEM images exhibit pores of different sizes. Contact angle values of all PU coatings are bigger than 90 indicating that the surfaces are hydrophobic. Using propylene carbonate in the preparation of methylene diphenyl diisocyanate (MDI) prepolymer and the chain extender in the PU coating formulation impacts the mechanical and electrical properties of the PU coatings as well as layered PU/PUr composite materials. In conclusion, not only the controllable physicochemical and mechanical properties of layered PUr/PU composites but also the usage potential of recycled PU scraps in these layered composites are very promising for better floor applications.

Our study is concerned with the development of a novel type of layer-by-layer (LbL) self-assembled membrane from a single cationic polyelectrolyte (PE) and blended anionic PEs. Their synthetic seawater stability is investigated as a function of PE type and blend ratios using quartz crystal microbalance-dissipation (QCM-D). These materials adsorbed into multilayers with significant viscoelasticity. Poly(allylamine hydrochloride) (PAH) and poly(vinylamine hydrochloride) (PVA) based LbL blend films did not show any multilayer decomposition with the addition of synthetic seawater regardless of blend ratio while chitosan based multilayers disintegrated. The flux of PVA based blend membrane to water with 1,000 ppm NaCl was found to be 6.7 L/ m 2 .h at 40 bar and the flux properties of the membranes were highly dependent on both the thickness and hydrophilicity of multilayers. Ion rejection can be controlled with the charge of the top layer consistent with a Donnan exclusion approach. Sodium ion rejection of 60.5 layered LbL blend membrane was 98.4% at 40 bar and it was determined that sodium ion rejection improved 110.7% compared to a commercial nanofiltration membrane. POLYM. ENG. SCI., 60:1006-1018, 2020

Superhydrophobic and oleophilic modification of commercial acoustic melamine foam (MF) was made in this study. The modification was carried out with chitosan (CHI) and silica particles (SiO 2 ), by using both a layer-by-layer-like approach (LbL) and dip coating technique. Subsequently, 1-octadecanethiol was used as a secondary modification agent. QCM-D, SEM, and FTIR analyses confirmed that the coating was successfully performed. After the modification, the column wall thicknesses increased than that of MF and they ranged from 25% to 48% for modified MF with an LbL-like approach (MMF) and modified MF via dip coating technique (MMFd), respectively. The sorption experiments showed that modified MFs, which had a water contact angle (WCA) above 160°, could sorb several model pollutants (vegetable oil, chloroform, ethanol, and toluene) up to 76–130 times their original weight. It had been determined that MMF protects its open-pore structure better than that of MMFd, which indicated that MF has a more uniform pore structure after modification. Furthermore, after 10 cycles of the sorption and release process, there was no significant change in sorption capacity, and they preserved their mechanical stability and flexibility.

This study deals with selective separation of mono- and divalent cations from aqueous salt solutions using polymeric films based on polyethylene (PE) and polyamide6 (PA6), and two different commercial nanofiltration (NF) membranes. The diffusion rates (D) of ions (Na + and Ca 2+ ), separation factors (α) and ion rejections (R) of the films and NF membranes are examined comparatively as well as their surface morphology and hydrophilicity. It is observed that the diffusion rates of Na + are in the range of 0.7–1.8 × 10 −8 cm 2 .s −1 in the decreasing order of PE > NF90 > NF270 > PA6 while Ca 2+ shows diffusion rates of 7.4–18.4 × 10 −8 cm 2 .s −1 in the increasing order of NF270 > NF90 ≈ PA6 > PE. Rejection values of the polymeric films and NF membranes against to Na + and Ca 2+ vary between 90% and 99.6%.The highest α(Ca 2+ /Na + ) is found to be 20 for PA6 film. D, α, and R value of both polymeric films and NF membranes are strongly affected by the existence of osmosis during diffusion-dialysis and the sizes of hydrated sodiu and calcium ions. In conclusion, the film based on PA6 may be a good alternative for selective separation of mono- an divalent cations.