Effect of Plasticizer on PVAc-d3 Dynamics using 2H Solid-State NMR

Rakesh R. Nambiar
Frank D. Blum, Missouri University of Science and Technology

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Poly(vinyl acetate) (PVAc) is an important polymer for use in many applications due to its various bulk and surface characteristics. The structure of poly(vinyl acetate) results in a relatively low glass transition temperature (Tg) and makes it important for processing and applications such as paints, adhesives, thin films and surface coatings. Poly(vinyl acetate) can also be easily plasticized, widening its range of applications. The term "plasticizer" refers to a species that will decrease Tg of a polymer.1 Polymer-plasticizer systems have been studied for years and continue to be of current interest. The effects of polymer-plasticizer interactions2 and plasticizer structure3 on polymer chain motions have been studied extensively, but there is still much to be learned in this area. Deuterium NMR is an excellent tool for studying the mobility of polymer chains. In this work, we report the investigation of the effect of plasticizer content on the Tg of poly(vinyl acetate) using deuterium nuclear magnetic resonance (2H NMR) spectroscopy. The methyl groups of poly(vinyl acetate) were deuterated in order to probe the mobility of their segments using the 2H NMR technique. Random orientations of the methyl groups, with respect to a magnetic field, are reflected as a powder pattern in the 2H NMR spectrum for segments with little or no motion. Segmental mobility averages the quadrupole couplings and ultimately leads to the collapse of the powder pattern into a single resonance for rubbery polymers when the motion is on the scale of or faster than the interactions.4