Polydiacetylene films

We first discuss the materials research which includes monomer synthesis, growth of monomer crystalline structures and polymerization in the solid state, yielding the requisite polymer structures. Next, the nonlinear optical experimental research is discussed which includes a novel experimental technique to measure x (w). Linear and nonlinear optical data obtained for the polydiacetylene films is subsequently presented. Detailed theoretical analysis relating the data to x (< >) and subsequently to its molecular basis will be discussed in a later publication. 

Figure 4. Absorption spectrum in the visible region of the multilayer polydiacetylene film deposited on a quartz substrate. Note the sharp absorption edge.

We assume that the chains were oriented parallel to the film plane but the chain direction were distributed randomly in the film plane. In this case, the correction factor for the chain orientation, , is 3/8. Consequently, the xSx value of the PTV cast film was calculated to be 1.2 x 10 9 esu, which is comparable to that of the highly oriented vacuum-deposited polydiacetylene film at the resonance with the exciton absorption. 

Carpick RW, Sasaki DY, Marcus MS, Eriksson MA, Bums AR. Polydiacetylene films a review of recent investigations into chromogenic transitions and nanomechanical properties. J Phys Condens Matter 2004 16 R679-R697. 

Scindia Y, Silbert L, Volinsky R, Kolusheva S, Jelinek R. Colorimetric detection and fingerprinting of bacteria by glass-supported lipid/polydiacetylene films. Langmuir 2007 23 4682-4687. 

Figure 7.33 Langmuir-Blodgett film formed by polydiacetylene (a) schematic diagram of Langmuir trough and (b) structure of a typical polydiacetylene film. (After Williams, 1983.)... 

Fig. 21. Absorption spectra of the monoerystal polydiacetylene film with R = CH 3-C6H4-S03-(CH 2)4-for the light polarized parallel (a) and perpendicular ( >) to the macromolecule chain [141]...

Although there has been a lot of interest in the PDAs due to their unique chemical, optical, and electronic properties, no method is available yet that is generally applicable to the formation of polydiacetylene films possessing suf-ficiendy high quality for technological applications, i.e., electronic and photonic devices, due to the insolubility of many polydiacetylenes. There is a continuous search for techniques to increase the processibility and quality of PDA film. Paley et al. reported a novel technique to obtain high-quality thin PDA films. They used photodeposition technique from monomer solutions onto UV trans-... 

Horvath, A., G. Weiser, G.L. Baker, and S. Etemad. 1995. Influence of disorder on the field-modulated spectra of polydiacetylene films. Phys Rev B 51 2751-2758. 

Chain Packing and Crystal Structures. The chain packing and the suhmolecular arrangement of repeat units and pendant side groups of macromolecules in crystalline domains of polymers can be visualized using contact mode SFM. The resolution is in most cases not true resolution, since the area of the contact area (1 — few nm ) exceeds the molecular scale and must be considered lattice resolution instead. The first example of molecularly resolved structures of a polymer dates back to 1988, when Marti and co-workers reported on an SFM study on a polydiacetylene film (128). Examples for resolved chain packing and polymer crystal structure determination at the surface of semicrystalline polymers include poly(tetrafiuoroethylene) (PTFE) (129,130), polyethylene (PE) (131-133), polypropylene (PP) (134,135), poly(ethylene oxide) (PEO) (136), aramids (137,138), and poly(oxy methylene) (POM) (139). 

Figure 2. Change in the visible absorption spectrum for thin polydiacetylene films exposed to deep-UV radiation.

Growth Kinetics of Polydiacetylene Films Prepared in Microgravity... 

DAMNA) (Figure 1). Frazier et al (6,7) reported the surface polymerization of polydiacetylene films from the photopolymerization of DAMt A monomer solutions. This unique photopolymerization process produces amorphous thin films of polydiacetylene, which can be used in the fabrication of waveguides and photonic devices. However films formed on earth are low quality and have defects that appear to be the result of buoyancy-driven convection. Microgravity experiments on the same system produced very high quality optical films. The lack of in-situ measurements limited the analysis of the effect of gravitational forces on the development of defects in the poyldiacetylene films. 

ELECTRIC FIELD INDUCED OPTICAL SECOND HARMONIC GENERATION AND POLARIZATION EFFECTS IN POLYDIACETYLENE FILMS... 

Results of electric-field induced second harmonic generation measurements on thin polydiacetylene films performed at 1 064 ym and 1.907 ym are reported At 1 064 m one observes large internal polarization fields depending on the polymer thin film morphology No such polarization effects are observed at 1 907 ym. 

Hattori, T. and Kobayashi, T., Femtosecond dephasing in a polydiacetylene film measured by degenerate four-wave mixing with an incoherent nanosecond laser, Chem. Phys. Lett., 133, 230, 1987. 

Induced Optical Second Harmonic Generation and Polarization Effects in Polydiacetylene Films D. Bloor and R.R. Chance eds., NATO ASI Series, E102, 317-324. 

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