Segmental dynamics of polymers in nanoscopic confinements, as probed by simulations of polymer/layered-silicate nanocomposites

• Published in: The European physical journal. E, Soft matter (Print) Vol. 12; no. 1; pp. 159 - 165
• Main Authors: KUPPA, V, FOLEY, T. M. D, MANIAS, E
• Format: Conference Proceeding Journal Article
• Language: English
• Published: Heidelberg Springer 01.09.2003
• Subjects: Applied sciences; Composites; Computer Simulation; Exact sciences and technology; Forms of application and semi-finished materials; Manufactured Materials; Models, Molecular; Motion; Nanotechnology - methods; Particle Size; Polymer industry, paints, wood; Polymers - chemistry; Porosity; Silicates - chemistry; Technology of polymers; Temperature; Ethylene oxide polymer; Clay; Molecular dynamics method; Theoretical study; Numerical simulation; Styrene polymer; Nanocomposite; Segmental movement; Modeling; Composite material; Confined space
• ISSN: 1292-8941; 1292-895X
• DOI: 10.1140/epje/i2003-10035-5

In this paper we review molecular modeling investigations of polymer/layered-silicate intercalates, as model systems to explore polymers in nanoscopically confined spaces. The atomic-scale picture, as revealed by computer simulations, is presented in the context of salient results from a wide range of experimental techniques. This approach provides insights into how polymeric segmental dynamics are affected by severe geometric constraints. Focusing on intercalated systems, i.e. polystyrene (PS) in 2 nm wide slit-pores and polyethylene-oxide (PEO) in 1 nm wide slit-pores, a very rich picture for the segmental dynamics is unveiled, despite the topological constraints imposed by the confining solid surfaces. On a local scale, intercalated polymers exhibit a very wide distribution of segmental relaxation times (ranging from ultra-fast to ultra-slow, over a wide range of temperatures). In both cases (PS and PEO), the segmental relaxations originate from the confinement-induced local density variations. Additionally, where there exist special interactions between the polymer and the confining surfaces ( e.g., PEO) more molecular mechanisms are identified.