Polymer films simulations

A. Milchev, K. Binder. Dewetting of thin polymer films adsorbed on solid substrates A Monte Carlo simulation of the early stages. J Chem Phys 705 1978-1989, 1997. 

The model for a filled system is different. The filler is, as before, represented by a cube with side a. The cube is coated with a polymer film of thickness d it is assumed that d is independent of the filler concentration. The filler modulus is much higher than that of the d-thick coat. A third layer of thickness c overlies the previous one and simulates the polymeric matrix. The characteristics of the layers d and c are prescribed as before, and the calculation is carried out in two steps at first, the characteristics of the filler (a) - interphase (d) system are calculated then this system is treated as an integral whole and, again, as part of the two component system (filler + interphase) — matrix. From geometric... 

A correlation can be made between the measured magnitude of the waveguide signals and the vapor pressures of the condensed vapors sensed. Three of the five polymer films tested showed extremely large responses to the simulant dimethyl methyl phosphonate (DUMP), and one of these films could detect DUMP vapor concentrations below the 20 ppm level. 

S. Izumisawa and M. S. Jhon, Molecular simulation of thin polymer films with functional endgroups, J. Chem. Phys. 117(8), 3972-3977 (2002). 

Metallized polypropylene (PP) is used today in many different fields such as automotive, decoration, electrical. In order to obtain a good adhesion between the aluminium and the polymer a pretreatment of the film prior to the metallization is necessary. Indeed, the very extreme surface of the polymer has to be modified in order to prepare it to a good adhesion with the metal. Thus the polymer is placed in a low pressure plasma of nitrogen with a corona discharge configuration of electrodes, and the metallization is carried out in situ after the pretreatment in nitrogen. This process, which simulates an industrial polymer film treatment has proven a great efficiency for very short treatment times (23 ms) (1).However, the mechanisms responsible for the improvement of adhesion are not totally explained yet. 

REID R. c., siDMAN K. R., SCHWOPE A. D. and TILL D. E., 1980, Loss of adjuvants from polymer films to foods or food simulants, effect of the external phase. Ind. Eng. Chem. Prod. Res. Dev. 19, 580-587. 

Summarizing, two conditions must be fulfilled in order to obtain from the simulations a confinement-induced and thickness-dependent distribution of the end-to-end distance for terminal subchains. First, a chain should be in contact with both interfaces. This happens only when the film thickness becomes comparable to the size of the chains and, obviously, explains why the confinement-induced mode does not exist in the bulk. Second, the interactions at the interfaces should be asymmetric One interface should immobilize the polymer chains, while the second one should only reflect them. This asymmetry could be induced by the nonequivalent preparation of the electrodes in the experiment While one interface is prepared by spin-coating, the other one is prepared by evaporation of aluminium on top of the polymer film (see Section II for details). A similar picture of asymmetry was found in studies on thin PS films, with a preparation procedure identical with ours. For thin PS films capped between two aluminum electrodes a three-layer model was proposed, in which, in addition to a middle-layer having bulk properties, a dead (immobilized) layer and a liquid-like layer were assumed to be present at the interfaces. 

From the foregoing analysis (Fig. 7) of simulation and experimental data we infer that the size scaling relation A7 oc Lr (where Lc Rq for clusters and nearly spherical confined spaces and L r for cylinders) is obeyed over a wide size domain of L 14 00 A (i.e., N = 14-4 x 10 for clusters and nearly spherical confined spaces), and of L 150-1000 A for cyhndrical channels. This broad range of size domain with the proper critical v 2/3 exponent indicates that it is unnecessary to replace 7 by a size-independent reference temperature, as proposed [158] to account for a lower scaling component reported for ( He) confined in polymer films over a narrow size domain [157, 192]. 

Fujiwara et al [51] have used molecular dynamics simulations to interpret the images obtained from STM experiments. The combined use of these two techniques is proving to be a very powerful tool for understanding the conformation of polymer films on surfaces. They showed that the individual polyimide strands observed were aligned parallel to the deposition direction of the Langmuir-Blodgett film. 

Peerce, P. J., Bard, A. J. (1980). Polymer films on electrodes m. Digital simulation model for cyclic voltammetry of electroactive polymer film and electrochemistry of poly(vinylferrocene) on platinum. J Electroanal Chem 114, 89-115. 

Fig. 11 Model of polymer film used in the present work. The system consists of 100 chains each consisting of 100 beads. The size of the simulation box is 32 T X 32 T X 32(7...

Fig. 6.4 Three simulations of how substrate surface chemistry influence polymer film dewetting. The left column indicates the surface chemistry of more wettable regions (white) and less wettable regions (black). The following columns indicate the evolution of an overlaying polymer fihn in time as the film is annealed. The difference between the three rows is the spacing of the wettable lines from 0.75Ah (a, top row), 1.00.lh (b, middle row), and (c, bottom row). Reprinted with permission [11]...

Numerical Simulation Methods Applied to Electroactive Polymer Films... 

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