Interaction in POSS-poly(ethylene-co-acrylic acid) nanocomposites

Use of polyhedral oligomeric silsesquioxane (POSS) in polymer-based nanocomposites is promising for the design of high-performance materials for several applications. In this study, nanocomposites based on ethylene-acrylic acid (EAA) copolymer and POSS molecules were prepared by melt mixing. In particular, partial cage POSS with different pendent organic groups was used to investigate the interaction between the -OH groups of POSS and the acrylic functionalities of the matrix. All nanocomposites were characterized by mechanical, rheological, thermal and spectroscopic analyses. In addition, PE-POSS compounds were prepared under the same processing conditions for sake of comparison. The POSS molecules affect the properties in the molten state and usually act as a plasticizer. However, this plasticizing effect should not be evident if the host polymeric matrix is able to interact with organosilicon molecules, in which case, the POSS molecules would confer an antiplasticizer effect. Therefore, all properties measured of EAA/POSS nanocomposites are the result of two contrasting phenomena, particularly the plasticizing and reinforcement effects. Moreover, the properties of these nanocomposites depend significantly on the presence of certain functionalities in the components and on possible interactions between them.