Nanonetworks of Multifunctional Polyhedral Oligomeric Silsesquioxane and Polypropylene Oxide

• Published in: Macromolecules 2008-10, Vol.41 (19), p.7122-7130
• Main Authors: Bian, Yu, Mijović, Jovan
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical properties; Exact sciences and technology; Polymer industry, paints, wood; Properties and testing; Technology of polymers
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma801044v

An investigation was carried out of the segmental and normal mode dynamics in multifunctional polyhedral oligomeric silsesquioxane (POSS)/polypropylene oxide (PPO) nanonetworks. The reaction kinetics and thermal properties of POSS/PPO nanonetworks are studied by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Dynamic behavior is investigated by broadband dielectric relaxation spectroscopy (DRS) and dynamic mechanical spectroscopy (DMS) over a wide range of frequency and temperature. Before the onset of reaction, POSS nanoparticles promote motions of PPO chains in nanocomposites. During the formation of nanonetworks, however, the presence of POSS nanoparticles causes gradual increase in the time scale of the segmental (α) and the normal mode (αN) process in POSS/PPO nanonetworks. Comparison of DRS and DMS results for the α process reveals identical trends with respect to POSS concentration and temperature. A detailed account of the effect of POSS structure, PPO molecular weight, extent of reaction and temperature on the molecular origin, temperature dependence and spectral characteristics of relaxation processes in POSS/PPO nanonetworks is provided. The results show how the properties of POSS/PPO nanonetworks can be controlled by the selection of POSS functional group and PPO molecular weight.