Polymer science molecular model

This review has shown that the analogy between P=C and C=C bonds can indeed be extended to polymer chemistry. Two of the most common uses for C=C bonds in polymer science have successfully been applied to P=C bonds. In particular, the addition polymerization of phosphaalkenes affords functional poly(methylenephosphine)s the first examples of macromolecules with alternating phosphorus and carbon atoms. The chemical functionality of the phosphine center may lead to applications in areas such as polymer-supported catalysis. In addition, the first n-conjugated phosphorus analogs of poly(p-phenylenevinylene) have been prepared. Comparison of the electronic properties of the polymers with molecular model compounds is consistent with some degree of n-conjugation in the polymer backbone. 

Advanced adhesives are composite liquids that can be used, for example, to join aircraft parts, thus avoiding the use of some 30,000 rivets that are heavy, are labor-intensive to install, and pose quality-control problems. Adhesives research has not involved many chemical engineers, but the generic problems include surface science, polymer rheology and thermodynamics, and molecular modeling of materials... 

Crystallization in polymers has long been one of the most difficult problems in polymer science. It was to our great surprise that the computer simulations proved very useful in studying this historical problem, if we properly devised the molecular models and the crystallization conditions. But I am aware that there are many problems in the present simulation. Major criticisms will be why the crystallization is so fast, what kind of relevance the present model has to real polymer systems, and how we can bridge the space and time gaps between the present model and real polymers. 

Figure 14.4 Primary sequence and molecular model of a coiled coil dimer and self-assembled polymer with the hydrophobic interface highhghted. The final bundle fiber structure is shown at the bottom. Reprinted from Wagner et al. (2005). Copyright 2005 National Academy of Sciences.

The application of porous media mechanics which traditionally was mostly focussed upon geomechanics, has spread to a vast area of science. This area includes polymer science, biomechanics, biomaterials, ceramics. Many of these areas of application require the integration of many physical phenomena into one single porous media model. Electrochemistry, statistical physics, fluid mechanics, molecular biology and electromagnetism are just a few examples of these. 

In mechanistic models these interactions can be directly simulated. Thus the issue of kinetic coupling (molecular interactions) may well be somewhat artificial and only introduced by analysis at the less detailed molecular or global levels. Likewise, the intrusions of diffusion may also be somewhat artificial and a result of modelling at the molecular or global level. That is, mechanistic simulations can now account for the movement as well as reaction of molecules and active centers (54). This becomes especially convenient when the device of a percolation lattice is used. Molecules can then be assembled, moved and reacted on the lattice which, in addition to allowing for simulation of the mechanism of diffusion in reaction, can also provide information about global product fractions, such as polymer gel fraction and cross-link density. The literature of polymer science is rich in these types of applications. 

Molecular modeling has reached into many domains of science and technology. One area that has a rich history of applied theory is polymer science. Indeed, many aspects of statistical thermodynamics were developed in an attempt to understand polymer systems. Unfortunately, many theories provide only macroscopic views of polymer systems and are sometimes out of date. 

Polymer science has undergone a transition recently. Many of the traditional computational tools used for atomistic molecular modeling are now being used in polymer science. In Chapter 3, Professor Vassilios Galiatsatos provides an account of how these modern computational methods are being implemented and refined by polymer scientists to complement existing theories developed by Flory, DeGennes, and others. The focus here is on homopolymers. 

Suknuntha, K., Tantishaiyakul, V., Vao-Soongnem, V., Espidel, Y., and Gosgrove, T. 2008. Molecular modeling simulation and experimental measurements to characterize chitosan and poly(vinyl pyrrolidone) blend interactions. Journal of Polymer Science Part B Polymer Physics 46 1258-1264. 

Pollock, M. J., MacGregor, J. F., and Hamielec, A. E. (1981) Continuous poly (vinyl acetate) emulsion polymerization reactors dynamic modeling of molecular weight and particle size development and application to optimal multiple reactor system design. Computer Applications in Applied Polymer Science, (ed. T. Provder), ACS, Washington, pp. 209-20. 

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