Crystallization in thin films

There has been very little work in this area to date. The structure of thin crystallized films of a diblock or a triblock copolymer deposited on silicon has been 

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In the early work of Rigby and Roe (370) it was shown that a imited atom model of PE would spontaneously pass from an isotropic to a nematic phase on lowering the temperature. More recently, the same model potential has been applied by Koyama and co-workers (460), who found a Tg at about 230 K, with significant ordering of the chains occurring between 300 and 330 K. The latter is taken to indicate incipient crystallization. The work on a polymer film by Ito and co-workers (340) used the same model, and found a crystalline structure below and at 300 K. Thus, if the simulation times are sufficiently long relative to the relaxation time of the modeled chains, it is possible to observe at least the onset of crystallization in a condensed phase. The timescale for crystallization in thin films may be shorter than in the bulk Ito and co-workers (340) have shown that their PE film forms... 

Padden, R J. Keith, H. D. Crystallization in thin films of isotactic polypropylene. J. Appl. Phys. 1966, 37, 4013-4020. 

Brinkhuis RHR, Schouten AJ. Thin-fikn behavior of poly (methyl methacrylates). 3. Epitaxial crystallization in thin films of isotactic poly(methyl methacrylate) using crystalline Langmuir-Blodgett layers. Macromolecules 1992 25 2717-2724. 

Taguchi K, Miyaji H, Izumi K, Hoshimo A, Miyamoto Y, Kokawa R. Growth shape of isotactic polystyrene crystals in thin films. Polymer 2001 42 7443-7447. 

The overall crystallization kinetics of polymers is governed by nucleation and growth of crystalline aggregates, and is influenced by the thermomechanical crystallization conditions and history, including temperature field, pressure, and effects of flow. Also, dimensionality of the process plays an important role. Usually, crystallization in thin films is slower than in polymer bulk, although the nucleation on film surfaces might markedly accelerate the crystallization. In addition, internal interfaces, for instance, in fiber-reinforced composites or in polymer blends, also influence the overall crystallization kinetics. 

Figure 13.8 Consecutive stages of isothermal crystallization in thin film of nanocomposite iPP/PP-g-MA/o-MMT (87 10 3 by weight), between glass sUdes, at 128°C. Reprinted from Nowacki, R., et al. Spherulite nucleation in isotactic polypropylene based nanocomposites with montmoriUonite under shear. Polymer 2004,45,4877-4892, with kind permission from Elsevier, Copyright 2004.

Hong S., MacKnight W. J., Russell T. P., and Gido S. P. (2001a) Orientationally registered crystals in thin film crystalline/amorphous block copolymers. Macromolecules 34 2398-2399. 

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