Tracking the interdiffusion of polymers at a molecular level by 1H dipolar filter solid-state NMR under fast magic angle spinning

Abstract

In this paper, we characterized the interdiffusion of deuterated polystyrene (PS-D) and hydrogenated poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) by ¹H dipolar filter solid-state NMR under fast magic angle spinning (MAS). It is observed that the interdiffusion process of PS-D/PPO is composed of two stages, the wetting stage and the diffusion stage. The characteristic time of the transition from the wetting to diffusion stage is independent of the temperature and PS-D molecular weight. On the other hand, the increment of dipolar filtered ¹H NMR signal intensity at the wetting stage depends strongly on the temperature. The PS-D chains can be easily mixed with the PPO chains intimately when the temperature is above the glass transition temperature (T_g) of PPO. However, when the temperature is below the T_g of PPO, the PPO chains are frozen and it is more difficult for the PS-D chains to approach the PPO at a molecular level.