Non-Equilibrium Phenomena in Confined Soft Matter: Irreversible Adsorption, Physical Aging and Glass Transition at the Nanoscale

ISBN-13: 9783319219479 / Angielski / Twarda / 2015 / 300 str.

Simone Napolitano

Opis

This book deals with those properties of non-equilibriumsoft matter that deviate greatly from the bulk properties as a result of nanoscale confinement.The ultimate physical origin of these confinement effects is not yet fully understood. At the state of the art, the discussion on confinement effects focuses on equilibrium properties, finite size effects and interfacial interactions. However this is a limited vision which does not fully capture the peculiar behaviour of soft matter under confinement and someexotic phenomena that are displayed. This volume will be organized in the following three main themes. Equilibration and physical aging: treating non-equilibrium via the formal methodology of statistical physics in bulk, we analyse physical origin of the non-equilibrium character of thin polymer. We then focus on the impact of nanoconfinement on the equilibration of glasses of soft matter (a process of tremendous technological interest, commonly known as physical aging), comparing the latest trends of polymers in experiments, simulations with those of low-molecular weight glass formers. Irreversible adsorption: the formation of stable adsorbed layers occurs at timescales much larger than the time necessary to equilibrate soft matter in bulk. Recent experimental evidence show a strong correlation between the behaviour of polymers under confinement and the presence of a layer irreversibly adsorbed onto the substrate. This correlation hints at the possibility to tailor the properties of ultrathin films by controlling the adsorption kinetics. The book reports physical aspects of irreversible chain adsorption, such as the dynamics, structure, morphology, and crystallization of adsorbed layers. Glass transition and material properties: this section of the book focuses on the spread of absolute values in materials properties of confined systems, when measured by different experimental and computation techniques and a new method to quantify the effects of confinement in thin films and nanocomposites independently on the investigation procedure will be presented."

Spis treści

Kinetics of irreversible chain adsorption, new insights from experiments and simulations.- Structure and dynamics of adsorbed polymer layers.- An investigation of irreversibly adsorbed polymer layers via Local Dielectric Spectroscopy.- History dependent temporal changes of properties of thin polymer films.- Equilibrium pathway of ultrathin polymer films as revealed by their surface dynamics.- Thickness and molecular mass dependence of the process in ultrathin films of PMMA – evidence of chain confinement.- Effect of confinement geometry on the out-of-equilibrium glassy dynamics.- Structural Relaxation of Confined Polymers (experiments).- Structural Relaxation of ultrathin polymer films (simulations).- Non-equlibrium structure affects the ferroelectric behavior of confined polymers.- Dynamics of Confined Glass-Forming Liquids in Near Equilibrium Conditions.- 1D confinement stabilizes non-equilibrium liquid phase with enhanced orientational order.

O autorze

Prof. Napolitano graduated in Materials Science from the University of Pisa in 2005 and two years after he received a PhD in Polymer Physics from KULeuven. After an appointment as postdoctoral researcher at the Research Foundation Flanders (FWO), in 2011 he joined the Université Libre de Bruxelles, where he holds a faculty position and leads the Laboratory of Polymers and Soft Matter Dynamics. His current research focuses on the molecular origin of the glass transition and the correlation between structure and dynamics in polymers and small molecules under nanoscopic confinement.

Blurb

This book presents cutting-edge experimental and computational results and provides comprehensive coverage on the impact of non-equilibrium structure and dynamics on the properties of soft matter confined to the nanoscale. The book is organized into three main sections:

·         Equilibration and physical aging: by treating non-equilibrium phenomena with the formal methodology of statistical physics in bulk, the analysis of the kinetics of equilibration sheds new light on the physical origin of the non-equilibrium character of thin polymer films. Both the impact of sample preparation and that of interfacial interactions are analyzed using a large set of experiments. A historical overview of the investigation of the non-equilibrium character of thin polymer films is also presented. Furthermore, the discussion focuses on how interfaces and geometrical confinement perturb the pathways and kinetics of equilibrations of soft glasses (a process of tremendous technological interest).

·         Irreversible adsorption: the formation of stable adsorbed layers occurs at timescales much larger than the time necessary to equilibrate soft matter in bulk. The question is posed as to whether this process could be considered as the driving force of equilibration. In this section, the investigation of the physics of irreversible chain adsorption is accompanied by a detailed analysis of the molecular dynamics, structure, morphology, and crystallization of adsorbed layers.

·         Glass transition and material properties: the discussion covers a broad range of non-equilibrium phenomena affecting different families of soft materials – polymers, low molecular weight glass formers, and liquid crystals. In these systems, geometrical confinement induces the formation of non-equilibrium phases, otherwise not

achievable via processing of bulk samples. The examples illustrated in this section show how non-equilibrium phenomena can be exploited as innovative processing parameters to fabricate novel nanomaterials with improved performance. Finally, the differences between experiments performed under equilibrium conditions and temperature scans from equilibrium to non-equilibrium states at the nanoscale are discussed.