of the Metamaterials Based on Various
Models of Polymeric Chains
Roman A. Gerasimov, Olga G. Maksimova, Tatiana O. Petrova, Victor A. Eremeyev and Andrei V. Maksimov
Abstract The formation of polymer coating on a solid substrate is investigated by means of computer simulation (Monte-Carlo method). The sticking coefficient depending on different factors affecting the adhesion of monomer units is calcu- lated. Mechanical properties are stimulated on the base of the hybrid discrete-continuous model, which describes the system consisting of flexible sub- strate and polymer coating. At different temperatures and intermolecular interac- tions constants, the dependencies of Young modulus on the deformation degree are calculated. Ferroelectric properties of the polymer coating depending on frequency and amplitude of external electricfield, temperature and interchain interactions are investigated.
Keywords Metamaterials
⋅
Ferroelectric polymer⋅
Monte-Carlo method⋅
Stockmayer potential⋅
Hybrid discrete-continual model⋅
Tension and bending deformations⋅
HysteresisR.A. Gerasimov (✉) ⋅ T.O. Petrova ⋅ V.A. Eremeyev
Southern Federal University, 105/42 Bolshaya Sadovaya Str., Rostov-on-Don 344006, Russian Federation e-mail: [email protected] T.O. Petrova e-mail: [email protected] V.A. Eremeyev e-mail: [email protected] O.G. Maksimova ⋅ A.V. Maksimov
Cherepovets State University, 5 Lunacharskii Av., Cherepovets 162600, Russian Federation
e-mail: [email protected] A.V. Maksimov
e-mail: [email protected]
© Springer Nature Singapore Pte Ltd. 2017
M.A. Sumbatyan (ed.), Wave Dynamics and Composite Mechanics for Microstructured Materials and Metamaterials,
Advanced Structured Materials 59, DOI 10.1007/978-981-10-3797-9_3
1
Introduction
Physics of surface and interfacial phenomena is an active research field, which continuously allows obtaining new important results. Currently, the field of knowledge related to the control of surface properties of new materials is inten- sively developing. Special attention is paid to the problems of regulation of the substrate surface wetting aimed at imparting them superhydrophobic and super- hydrophilic properties [1–6]. Among physical and chemical methods of surface modification, it is essentially to note such as plasma treatment, electrodeposition, lithography, etching, polymer grafting [7–9]. The methods of polymer chains grafting are particularly attractive, as they allow to selectively changing some properties of substrate surface: adhesion, wettability, tribological properties; with- out changes of physical properties of the substrate to give its surface the specific properties of the grafted polymer [3,8]. A wide range of grafted polymer chains allows selecting necessary characteristics of surface of phase interface and obtain in new hybrid materials. Moreover, this method allows obtaining rough and porous surfaces, what gives the opportunity to imitate the lotus leaf structure. In this case, wetting of the surface is defined both by chemical nature of the grafted compounds and by microtexture of the coating [3].
The grafted polymer layers have a broad prospect of application for preventing capillary condensation and icing, protection against corrosion and biofouling, hydroprotection of reinforced concrete structures, creating waterproof textiles. The surface-modified materials may have the ability to self-cleaning and non-wetting, to responding the changes at environmental conditions (temperature, light radiation, pH or solvent composition), may have antibacterial and antistatic properties.
The surfaces modified by grafted polymers are the most promising fields of application in nanotechnologies and micromechanics. Materials of this kind are widely used in different industries: they are used by creation of sensitive mem- branes and filters, biochips and biosensors; for enhancing foreign bodies’ bio- compatibility, regulation of adhesion, friction, surface wettability, as protective coatings for glass, metal, wood, ceramics, and textiles. Modification of textile fibers by polymer coatings allows obtaining new materials with preset properties. Formed on the surface, nano-rough polymerfilm gives textile materials with both hydro- and oleophobic properties allowing their application as protective clothing [10]. Such artificial materials the properties of which are mainly determined by their structure (in this case, by the surface structure) are called“metamaterials”.
Recently, on the way to implementation of “smart” surfaces, the synthesis of polymer brushes has gained particular attention [11]. Polymer brush is a monolayer of polymer chains linked with some impermeable surface by terminal groups. There are two fundamentally different methods to create such polymer brushes [12]. By chemical method, terminal groups are“sewn” to some surface by chemical bond- ing. The example of such systems is not only flat brushes in which the chains are grafted to flat surface (Fig.1a), but also some regularly branched polymers (stars with a large number of branches can be considered as spherically convex brushes,
and comb-shape polymers, as brushes around the convex cylindrical surface (Fig.1b and c).
By the other method of brush formation, a very important property of polymer molecules is used, which is the basis for the organization of complex biological structures, namely, the ability of macromolecules to self-organization. A necessary condition for the self-organization is the existence of different groups in macro- molecules. Usually, there are monomer units with different groups. In the simplest cases it is sufficiently to have only two kinds of monomer units in each polymer molecule (two-component copolymer). The driving force of self-organization is intermolecular interaction. There are both the intra- and inter-component interac- tions and interaction with the environment, for example with a solvent, a solid phase surface, i.e., with particles which may be present in the system, etc. Thefirst effects determine self-organization, when it occurs without a solvent (or at a low solvent content). Intermolecular interactions are much weaker than the covalent ones. Therefore, chemical structure is not changed during the self-organization, and everything is defined by intermolecular interactions in the system with the given chemical structure.
Also, in recent years, delicate experimental methods have made possible to reveal many interesting properties of solids, determined both by the influence of the solid body surface, and primarily due to its modification during the adsorption of
Fig. 1 The flat polymer brush with the chain height h (a) and regularly branched polymers as examples of brushes: spherical brush (b), cylindrical brush (c)
active elements and sputtering of ultrathin multilayer structures [13,14]. Improved resolution of various experimental techniques and improved methods of new materials producing allow direct measurements of surface properties. Therefore, results and predictions of theory and computer simulation of surface characteristics of solid bodies can be successfully tested. And better understanding of surface properties can lead to important new applications.
For elastic nano-scale bodies, the surface tension plays a significant role and influences on the deformation of bodies as a whole. Also, in a number of recent works [15–19], attempts were made to use the accounting methods of surface effects for nano-scale piezoelectric and flexoelectrical bodies. Despite a consider- able number of approaches and results, a fairly complete and strict analytic theory of surface effects for nano-scale piezoelectric and ferroelectric metamaterials still does not exist. Furthermore, by taking the defining relations connecting the surface tension and electrical activity, the problems of complete classical and generalized statements encounter serious difficulties. For example, the theory for static prob- lems of piezoelectricity with surface effects, presented in the work [20], see also [17–19, 21, 22], raises a number of problems relating to the formulation of boundary conditions, to the questions of solvability, uniqueness of solutions, etc. Mathematical study of boundary-value problems for elastic solids with surface stresses was performed in [23–27] where existence and uniqueness of week and strong solutions is proved. In particular, in [24] the stiffening effect of surface elasticity was confirmed. In the case of piezoelectric and magnetoelastic solids the similar analysis was given in [28–30].
Therefore, in recent years, methods of computer experiment have become an instrument used in many fields of science. Motivation for their application to the study of physical systems is diverse. One of the main motives is elimination of the limitations inherent in analytical models. Usually, by analytical analysis of the problem (if it is possible in general), different approximations are used. The application of computer simulation techniques gives the opportunity to study complex systems, not investigated analytically previously.
In this paper, for computer simulation of mechanical and electrical properties of metamaterials, we will apply Monte-Carlo method for numerical statistical description of macroscopic systems, widely used for investigations of bulk prop- erties of various materials [31, 32] and a powerful tool in the study of complex molecular systems [15,33, 34]. In Monte-Carlo method, the solution of dynamic equations for particles is replaced by the generation of some stochastic process. Such technique provides quite simple calculation of average values for various physical quantities within the canonical ensemble. Alongside with the description of bulk characteristics, Monte-Carlo method is used quite successfully for the simulation of crystal growth and studying the properties of emerging surface structures [33, 34]. The properties of crystalline surfaces are often described by means of lattice models. Dynamics of crystal growth is simulated by random processes of adsorption, evaporation and surface transport. The Monte-Carlo method allows directly simulating such dynamic processes.