Positron Annihilation and Chemistry of Groups in Hyperbranched Polymers

Abstract

In this paper, both lifetime and intensity in hyperbranched polymers were measured by using positron annihilation lifetime spectroscopy (PALS) measurements. Ortho-positronium properties upon the degree of branching (DB) have been studied; o-Ps lifetimes maintain a constant while an increase in o-Ps intensities has been detected with DB increasing. Which is inconsistent with author’s prediction and indicate that interactions between positronium and the free-volumes are strongly depend on not only the free-volume size properties but also its chemistry environment, due to the variations in the distribution of the different ending groups: –OH and -CH3, caused by DB changes in hyperbranched polymers. The present works demonstrate that in the polar-polymeric application of PALS, effects of the distribution of polar groups should be properly taken into consideration.