دانلود کتاب فیزیک پلیمر، مقدمه‌ای برای دانشمندان و مهندسان، از هم گسیخته

Polymers have transformed every aspect of our life, from disposable consumer goods (plastic bags and bottles), common medical devices (contact lenses and stents), transportation (tires and aerospace composites) to integrated circuits (IC substrates and packaging of semiconductor chips). To satisfy these demands, the chemical industry produces over 400 million tons of polymers each year. A byproduct of such enormous amounts of polymers is a significant plastic pollution problem, from islands of plastic trash in our oceans to polymeric nanoparticles permeating our ecosystem. Moreover, all of us are made of biopolymers encoded in genes via DNA—a long-chain, double-helical biological macromolecule. In summary, polymers are ubiquitous in our world. The goal of this book is to introduce students to the core concepts of polymer physics. The topics are selected in such a way as to provide readers with a basic knowledge of the underlying molecular processes that are responsible for the macroscopic properties of polymers. The pedagogy is complemented by solutions to 60 problems targeting both an improvement in problem-solving skills and providing a “boot camp” for nurturing the skills necessary for understanding the content material. This should prepare students to tackle advanced topics of modern polymer science that go beyond the scope of the book. Ultimately students should be able to apply learned concepts to conduct a critical analysis of experimental data and to comprehend the current literature. The book is based on topics for a two-semester introductory course that I taught at the University of Connecticut, the University of Akron and the University of North Carolina at Chapel Hill. It is written for undergraduate and graduate students majoring in chemistry, physics, chemical engineering and materials science. A basic knowledge of introductory chemistry, physical chemistry, physics and calculus will help with understanding the material. In writing the book, however, I have tried to make it self-contained; all the supporting information is covered in text boxes and in footnotes accompanying the text. The discussion topics are augmented by 315 figures from examples in the current literature, and each chapter concludes with a problem set totaling over 130 problems. In compiling the material, I have selected noncontroversial topics which have been broadly adopted by the polymer and soft matter communities. The subjects reflect my understanding of what matters most in the field. And if there is an underlying theme, it is the idea that a polymer’s specific packing parameter (introduced in Chapter 3) plays an integral role in characterizing thermodynamics and dynamics of polymers. Introduced in the late 1960s by I. M. Lifshitz, this parameter is mostly overlooked in modern literature. The discussion begins with the hypothesis of polymers and how they are made (Chapter 1). It introduces a chain’s degree of polymerization, molar mass and molecular weight, and considers the distributions that result from different types of polymerization reactions. Chapters 2 and 3 deal with individual chain properties by introducing ideal and real chain models. In particular, Chapter 2 highlights the effect of chain connectivity, bond lengths, valence angles and the torsion potentials on a chain’s rigidity. These attributes manifest in the chain’s dimensions quantified by its mean square end-to-end distance and its radius of gyration. Those features show how the chemical structure of a polymer chain is masked by a chain’s Kuhn length and its repeat-unit projection length. The section ends with a derivation of the chain’s size distribution function and an overview of a chain’s deformation under an applied external force. Chapter 3 begins with a discussion of the effect of the repeat unit excluded volume on the distribution of a chain’s end-to-end distance. It points out that the degree of chain swelling is directly related to the chain’s packing parameter characterizing the relative importance of the chain’s rigidity and its repeat unit excluded volume. The discussion continues with the adaptation of the lattice model to describe chain swelling and collapse in the presence of solvent. The polymer/solvent affinity is quantified by introducing the Flory interaction parameter that controls solvent quality for the polymer backbone. The Flory approach is used to account for chain swelling and collapse. In the collapsed (globule) state, the effect of the globule’s surface energy on the coil-globule transition is discussed. This analysis highlights the conditions leading to a breakdown of the Flory approach to the coil-globule transition. The thermal blob concept is introduced to qualitatively describe conformations of polymer chains in both swollen and collapsed states. The section ends with a discussion of a real chain’s deformation by an external applied force, and chain confinement within a pore. Chapter 4 focuses on the thermodynamics of polymer solutions highlighting the specifics of polymers in comparison with the properties of ordinary liquids and mixtures. Again, it starts with the adaptation of the lattice model to polymer solutions and its application to solution phase separation. The following discussion presents a scaling model of polymer solutions by introducing the solution correlation length (blob) corresponding to a length scale at which the intrachain interactions responsible for a chain swelling in a dilute solution are screened. The scaling diagram of states in good, theta, and poor solution regimes is constructed. Furthermore, the developed scaling approach is used to show the limitations of the lattice model for describing polymer solution properties and to highlight the importance of the packing parameter for different solution properties. A large portion of the chapter is devoted to a discussion of scattering from polymer solutions in dilute and semidilute regimes. Chapter 5 demonstrates how to apply the concepts of polymer solutions developed in Chapter 4 to polymer brushes, block copolymer self-assembly and solutions of charged polymers. The topics overviewed in this chapter include: the Flory-like and Alexander–de Gennes models of polymer brushes, the Daoud– Cotton model of polymer stars, steric interactions between brush layers, the closed-association model of block copolymer self-assembly in solutions, the blockcopolymer self-assembly at surfaces and properties of polyelectrolyte chains in dilute and semidilute solutions. Chapter 6 discusses properties of blends of linear polymers and melts of copolymers. It begins with an extension of the lattice model to polymer blends and its application to chain collapse in the presence of a polymeric solvent. Then the origin of microphase/mesophase separation in melts of copolymers is discussed. The physical origin of the emerging domain structure is illustrated by deriving the free energy describing individual block segregation in symmetric diblock copolymers. A free energy analysis highlights the importance of the surface free energy of the interface between two immiscible blocks, and the elastic free energy of two brushlike layers formed by blocks on both sides of the interface. The structure factors are calculated for both blends of linear chains and melts of diblock copolymers. The structure factor of diblock copolymer melts is shown to have a characteristic peak at length scales commensurable with the block’s dimensions; such peaks are already appearing in the disordered state and the amplitudes of those scattering peaks increase as the system approaches an order–disorder transition. Chapter 7 addresses the fundamentals of network elasticity and gel swelling. The discussion covers linear and nonlinear network deformation regimes, as well as the role of entanglements in network and gel mechanics. The chapter ends with an overview of the properties of gels made of biopolymers and charged polymers. Chapters 8 presents phenomenological aspects of polymer viscoelasticity and an overview of Maxwell, Voigt and generalized Maxwell models. It introduces the Boltzmann superposition principle and applies it to describe the viscoelastic response of polymer melts and networks undergoing constant-rate and oscillatory deformations. The storage and loss moduli are calculated and their specific features are discussed for different phenomenological models of melt and network viscoelasticity. Chapter 9 focuses on molecular models of polymer dynamics in solutions, melts and networks. The discussion begins with an overview of Brownian motion and a derivation of the Stokes–Einstein relationship between the self-diffusion coefficient and the friction coefficient in a dilute solution of particles. The result is obtained in the framework of Langevin dynamics. This approach is extended to relaxation dynamics of polymer chain by reformulating the Rouse and Zimm models in terms of the real-space mode representation instead or the usual Fourier mode analysis. This approach is used to calculate the stress relaxation modulus, the chain’s spectrum of relaxation times and the viscosity of polymer solutions and melts. The dynamics of semidilute polymer solutions are described in the framework of a scaling approach by taking into account the screening of the hydrodynamic interactions on length scales of the solution correlation length. The final sections of the chapter deal with chain entanglements in melts and solutions. It introduces an entanglement criterium by expressing the entanglement degree of polymerization in terms of the chain’s packing parameter. This discussion is followed by calculations of the storage and loss moduli in a melt of entangled polymer chains. The concept of entanglements is extended to polymer solutions by representing polymers as chains of correlation blobs. The chapter ends with a brief overview of the reptation motion of stars and comb-like polymers in a melt. This book would not be possible without undergraduate and graduate students at the University of Connecticut, University of Akron and University of North Carolina at Chapel Hill, who signed up for my classes over the last twenty years. They provided comments on the topic presentations and problem sets. I am grateful to Michael Jacobs, Ryan Sayko, Yuan Tian and Zilu Wang for a critical reading of the manuscript and for helping with the figures. I value my lengthy discussions with Professor Sergei Sheiko on polymer physics and polymer materials over the last thirty-some years. I also thank my former and current colleagues for numerous discussions on the book topics. Those include Professors Douglas Adamson, Matthew Becker, Ralph Colby, Igor Erukhimovich, Gary Grest, Alexander Grosberg, Ludwik Leibler, Patrick Mather, Elie Raphael, Michael Rubinstein, Thomas Seery, David Simmons, Robert Weiss, Marcel Utz, Bryan Vogt and Ekaterina Zhulina. I’m indebted to Edward Samulski for editorial comments and suggestions; our hours-long discussions helped me shape this book. I thank the National Science Foundation for supporting my research which allowed me the luxury of working on the book. Partial support from the Mackenzie Family fund was essential at the final stage of the book writing. This book would never have been completed without persistent support and encouragement from Sonke Adlung (Oxford University Press).