Heats of adsorption in the mixed polymer systems.

Adsorption of poly(butyl methacrylate) and polystyrene on aerosil from dilute, semidilute, and concentrated solutions has been studied. Using IR spectroscopy the shifts in the position of bands responsible for the vibration of free and bound OH-groups were found. According to the method proposed by Kiselev, the energies of adsorption interaction Q between OH-groups of adsorbent and polymer functional groups were calculated. The heats of adsorption were calculated as the product Q by p (p is the fraction of the bound segments). For the first time for the adsorption from the polymer mixtures, the adsorption heats were measured simultaneously separately for each polymer component and under dilute and concentrated regimes of solutions. It was established that the heats of adsorption of polymers and their mixtures from dilute, semidilute, and concentrated solutions are dependent on the values of adsorption and on the fraction of the bound segments. Increasing adsorption in the dilute solutions brings about the diminishing of the fraction of the bound segments which determine the adsorption heat. The adsorption heats from the mixed systems are lower as compared to adsorption heats from binary solutions.