We observe that the system trajectory on the free energy landscape is multi-dimensional and cannot be reduced to motion along a one-dimensional path on this surface. In order to elucidate the collective dynamics of the multiple degrees of freedom, the most likely path is identified on the free energy landscapes. Since the majority of natural and artificial surfactants are ionic, we also study the effects of electrostatic interactions on self-assembly of ionic surfactants. By solving the Poisson equation, it is shown that electrostatic potentials effectively increase (decrease) energy barriers of the addition (removal) of a surfactant molecule to (from) a micelle. It is anticipated that the approaches discussed in this study can be extended to investigation of more complex dynamic processes in amphiphilic systems.
We demonstrate that neglecting their contribution leads to qualitative discrepancies in predicted surfactant addition rates and propose a stochastic model for the monomer addition which takes the additional degrees of freedom into account. The model parameters are extracted from molecular dynamics simulations and the surfactant addition rates are determined from Brownian dynamics simulations of this model. The obtained addition and removal rates are then incorporated into the kinetic model of micelle formation and disintegration. It is expected that insights gained in the course of development of the multi-scale model for this relatively simple self-assembly process will aid in the development of models for dynamics of more complex processes in amphiphilic systems such as collision of reverse micelles involved in formation of nanoparticles, rheology of worm-like micellar solutions, and fusion of lipid bilayers.
Dynamics of Surfactant Self-Assemblies explains the dynamics of micellar equilibria, tracking surfactant exchange, and micelle formation/breakdown processes. Highlighting the structural similarities of amphiphilic block copolymers to surfactants, this volume elucidates the dynamics of more complex self-assemblies that surfactants and amphiphilic block copolymers form in solutions. The book first discusses self-assembling processes taking place in aqueous surfactant solutions and the dynamic character of surfactant self-assemblies. The next chapter reviews methods that permit the study of the dynamics of self-assemblies. The dynamics of micelles of surfactants and block copolymers, solubilized systems, microemulsions, vesicles, and lyotropic liquid crystals/mesophases are reviewed successively. The authors point out the similarities and differences in the behavior of these different self-assemblies. Much emphasis is put on the processes of surfactant exchange and of micelle formation/breakdown that determine the surfactant residence time in micelles, and the micelle lifetime. The last three chapters cover topics for which the dynamics of surfactant self-assemblies can be important for a better understanding of observed behaviors: dynamics of surfactant adsorption on surfaces, rheology of viscoelastic surfactant solutions, and kinetics of chemical reactions performed in surfactant self-assemblies used as microreactors. Dynamics of Surfactant Self-Assemblies offers a unique and comprehensive review of the literature that exists on the dynamics of the various surfactant self-assemblies and a unified perspective on this topic. It provides researchers with a useful guide for the dynamics of the surfactant systems that they wish to investigate.
Discover how the latest computational tools are building our understanding of particle interactions and leading to new applications With this book as their guide, readers will gain a new appreciation of the critical role that particle interactions play in advancing research and developing new applications in the biological sciences, chemical engineering, toxicology, medicine, and manufacturing technology The book explores particles ranging in size from cations to whole cells to tissues and processed materials. A focus on recreating complex, real-world dynamical systems helps readers gain a deeper understanding of cell and tissue mechanics, theoretical aspects of multiscale modeling, and the latest applications in biology and nanotechnology. Following an introductory chapter, Multiscale Modeling of Particle Interactions is divided into two parts: Part I, Applications in Nanotechnology, covers: Multiscale modeling of nanoscale aggregation phenomena: applications in semiconductor materials processing Multiscale modeling of rare events in self-assembled systems Continuum description of atomic sheets Coulombic dragging and mechanical propelling of molecules in nanofluidic systems Molecular dynamics modeling of nanodroplets and nanoparticles Modeling the interactions between compliant microcapsules and patterned surfaces Part II, Applications in Biology, covers: Coarse-grained and multiscale simulations of lipid bilayers Stochastic approach to biochemical kinetics In silico modeling of angiogenesis at multiple scales Large-scale simulation of blood flow in microvessels Molecular to multicellular deformation during adhesion of immune cells under flow Each article was contributed by one or more leading experts and pioneers in the field. All readers, from chemists and biologists to engineers and students, will gain new insights into how the latest tools in computational science can improve our understanding of particle interactions and support the development of novel applications across the broad spectrum of disciplines in biology and nanotechnology.
Molecular modeling (MM) tools offer significant benefits in the design of industrial chemical plants and material processing operations. While the role of MM in biological fields is well established, in most cases MM works as an accessory in novel products/materials development rather than a tool for direct innovation. As a result, MM engineers and practitioners are often seized with the question: "How do I leverage these tools to develop novel materials or chemicals in my industry?" Molecular Modeling for the Design of Novel Performance Chemicals and Materials answers this important question via a simple and practical approach to the MM paradigm. Using case studies, it highlights the importance and usability of MM tools and techniques in various industrial applications. The book presents detailed case studies demonstrating diverse applications such as mineral processing, pharmaceuticals, ceramics, energy storage, electronic materials, paints, coatings, agrochemicals, and personal care. The book is divided into themed chapters covering a diverse range of industrial case studies, from pharmaceuticals to cement. While not going too in-depth into fundamental aspects, the book covers almost all paradigms of MM, and references are provided for further learning. The text includes more than 100 color illustrations of molecular models.
Computer simulations can be used in parallel with experimental techniques to gain valuable insights into physical systems, test theoretical models or predict new be- haviour of molecular materials. Long time and large length scales, in combination with problems of phase space sampling, present a grand challenge for simulations of self-organising molecular materials. In the work presented in this thesis, the aim has been to develop and apply new or recent simulation models and methods to address these issues, with the aim of producing improved simulations of molecular materials. A new anisotropic model for simulating mesogenic systems has been developed, based on a soft core spherocylinder potential. This model is tested for single site systems and a multipedal liquid crystalline molecule, using conventional molecular dynamics simulations. It is used also to map out an approximate phase diagram for a main chain liquid crystalline polymer as a function of the volume fraction of the mesogenic unit; and to study the e?ects of a chiral medium on?exible achiral dopant molecules. Results here, show a preferential selection of conformations of similar chirality to the solvent. Later in the thesis, this new soft core spherocylinder model, is combined with a recently developed simulation methdology, Statistical Temperature Molecular Dynamics, to study the isotropic-nematic phase transition of a single site mesogen and the isotropic-lamellar phase transition of a model rod- coil diblock copolymer, using a single simulation to span the temperature window corresponding to the phase transition. Additional simulations combine a mesoscopic simulation method, Stochastic Ro- tational Dynamics, with a coarse grained surfactant model. This allows a computa- tionally e?cient solvent description while maintaining correct hydrodynamics. Re- sults presented here include the formation of a bilayer, via spontaneous self-assembly of surfactant molecules, and information on the pathways of micelle formation. In the?nal result chapter of this thesis, Hamiltonian replica exchange simulations are performed employing soft-core replicas for a Gay-Berne system. The simulation results show an order of magnitude increase in equilibration speed of the ordered phase when compared to conventional simulations of a Gay-Berne?uid.
Organic Materials as Smart Nanocarriers for Drug Delivery presents the latest developments in the area of organic frameworks used in pharmaceutical nanotechnology. An up-to-date overview of organic smart nanocarriers is explored, along with the different types of nanocarriers, including polymeric micelles, cyclodextrins, hydrogels, lipid nanoparticles and nanoemlusions. Written by a diverse range of international academics, this book is a valuable reference for researchers in biomaterials, the pharmaceutical industry, and those who want to learn more about the current applications of organic smart nanocarriers. Explores the most recent molecular- and structure-based applications of organic smart nanocarriers in drug delivery Highlights different smart nanocarriers and assesses their intricate organic structural properties for improving drug delivery Assesses how molecular organic frameworks lead to more effective drug delivery systems
