NMR investigation on the thermogelation of partially hydrolysed polyacrylamide/polyethylenimine mixtures.

Since the introduction of polyethylenimine (PEI)/acrylamide-based polymer gel systems in the late 90's, the literature knowledge on the crosslinking mechanisms between the various polymers (PAM, PHPA, and PatBA) and the crosslinker (PEI) was only limited to observations on gelation times and gel strength variations compared to other gel systems. In this paper, classic proton and carbon nuclear magnetic resonance "NMR" experiments and advanced 2D DOSY and NOESY techniques were employed for studying the interactions between the amine groups of PEI and amide or carboxylate groups of partially hydrolysed polyacrylamide (PHPA). Among the many possibilities, we showed that the interaction occurring during thermogelation is mainly due to covalent bonding.

Prediction of Lattice Constant of AXY Cubic Crystals Using Gene Expression Programming.

Lattice constant is one of the paramount parameters that mark the quality of thin film fabrication. Numerous research efforts have been made to calculate and measure lattice constant, including experimental and empirical approaches. Not withstanding these efforts, a reliable and simple-to-use model is still needed to predict accurately this vital parameter.

Rheological behaviour and adsorption phenomenon of a polymer-particle composite based on hydrolysed polyacrylamide/functionalized poly(styrene-acrylic acid) microspheres.

The properties in aqueous solution of polymer-particle composites (PPC) depend on the size and the concentration of both the particles and the polymers as well as the interactions between them. In this work, rheological behaviour was studied in a semi-diluted regime of partially hydrolysed polyacrylamide (HPAM) with 2Rg/d a particle diameter/polymer gyration radius (Rg) ratio and a confinement parameter (pc) that were both greater than 1. Rg is the polymer gyration radius and d the particle diameter.