Free-Volume analysis of PAMAM dendrimers by means of positron annihilation lifetime spectroscopy

Abstract

Polymeric structures known as dendrimers branch around a nucleus and contain functional groups that can affix surface groups to their ends. The inherent structural free volume of these materials makes them attractive for various important applications in the fields of biotechnology and nanotechnology. The purpose of this research was to examine the free volume behavior of ester- and acid-terminated poly(amidoamine) (PAMAM) dendrimers cored with tris(2-aminoethyl)amine (TREN) for the first three generations (0.5, 1.5, and 2.5 generations). Positron annihilation life spectroscopy (PALS) was used to analyze and discuss the size and fractions of hole-free volume generated by thermal effects in the temperature range of 10 C-degrees to 80 C-degrees. In addition, these PALS results may be related to the entanglement and deformability of the generation-dependent architecture and the influence of the surface groups.