The dynamic mechanical and rheological behavior of polyelectrolyte coacervates and complex precipitates is of interest for many applications ranging from health to personal care. Hydration is an important factor, but its effect on the dynamic properties of polyelectrolyte complexes (PECs) is poorly understood. Here, we describe the dynamic behavior of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) complex precipitates at varying relative humidity values and temperatures using both dynamic mechanical analysis (DMA) and all-atom molecular dynamics simulations. To mirror the experimental system via simulation, the water content within the PEC is measured and used as the parameter of interest, rather than relative humidity. In experimental DMA, modulus decreases with both increasing water content and temperature. The data are superimposed into a super-master hydrothermal curve using the time-temperature superposition principle and the time-water superposition principle for the first time. The temperature-dependent shift factor (aT) follows an Arrhenius relation, and the water-dependent shift factor (aw) follows a log-linear relation with water content in the complex. These results suggest that both temperature and water affect the dynamics of the PEC by similar mechanisms over the range investigated. Allatom molecular dynamics simulations show that an increase in water content and temperature lead to similar changes in polyelectrolyte chain mobility with little effect on the number of intrinsic ion pairs, suggesting the validity of time-water and time-temperature supposition principles.

Tightly and loosely bound water molecules within polyelectrolyte multilayers are examined as a function of temperature and salt.

Pretreatment coatings applied to metals are essential in the overall performance of anticorrosion coating systems. Hexavalent chromium, a widely used pretreatment for aluminum is now considered harmful. Therefore, a need for environment‐friendly yet efficient and scalable pretreatment coatings has emerged. Here, the authors present the spray‐assisted layer‐by‐layer (LbL) assembly and anticorrosion performance of a highly ordered polymer–clay nanocomposite coating. This approach is an entirely water‐based process, allowing for application over large surface areas. This novel pretreatment coating (25 wt% clay) presents a brick‐and‐mortar multilayered structure, where the montmorillonite clay (MMT) acts as a physical oxygen barrier, while preventing the dissolution of corrosion products—thus delaying corrosion. The branched polyethylenimine polymer (BPEI) mortar provides surface buffering once the corrosion process initiates. The anticorrosion properties of the LbL coating are evaluated using electrochemical measurements and salt‐spray testing. This BPEI/MMT system presents good anticorrosion properties, making it a potential alternative pretreatment.

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