Poly Langmuir-Blodgett films

To fit the experimental results, it is necessary to fix the overall phase. This can be done, for example, by defining h as a real quantity (/ / = 0). The values found for the coefficients /, g, and h can then subsequently be used to calculate the values of the components of the second-order susceptibility, X(2). This is done in detail for a Langmuir-Blodgett film of a poly(isocyanide) in the following section. Note that both phase and magnitude of all tensor components are relative values. The absolute phase cannot be determined... 

The material system is a Langmuir-Blodgett film of the S enantiomer of a chiral polymer deposited on a glass substrate. The polymer is a poly(isocyanide)30 functionalized with a nonlinear optical chromophore (see Figure 9.14). In this particular system the optical nonlinearity and chirality are present on two different levels of the molecular structure. The chirality of the polymer is located in the helical backbone whereas the nonlinearity is present in the attached chromophores. Hence, this opens the possibility to optimize both properties independently. 

A Marietta, D Gongalvcz, ON Oliveira Jr., RM Faria, and FEG Guimaraes, Circular dichroism and circularly polarized luminescence of highly oriented Langmuir-Blodgett films of poly(/j-phenylene vinylene), Synth. Met., 119 207-208, 2001. 

Su A, Tan S, Thapa P, Flanders BN, Ford WT. Highly ordered Langmuir-Blodgett films of amphiphilic poly(propylene imine) dendrimers. J Phys Chem C 2007 111 4695 -4701. 

Circular surface micelles have also been observed for non-ionic block copolymers. Li et at. (1993) reported TEM and AFM of starfish micelles formed by PS-poly(n-butyl methacrylate), PS-poIy(rm-butyl methacrylate) and poly(fer<-butyl acrylate) diblock copolymers. Plateaus observed in surface/area isotherms of the Langmuir-Blodgett films at the air-water interface were consistent with the formation of surface micelles. 

The results illustrated above show that the CFT method is suitable for making chemical-sensor measurements using both bulk polymers and, in particular, thin film materials that are intrinsically weak conductors. Therefore, the CFT looks premising for such materials as poly(phenylacetylene) derivatives 24., for which carefully shielded electrometer measurements have been required in the past because of current levels at the threshold of detectability. Furthermore, the fact that the CFT always makes AC measurements reduces the problem of DC polarization of electrodes. In addition, the CFT approach should be suitable for other "chemiresistor" applications, such as the metal-substituted phthalocyanines proposed by Jarvis et. al. 2 and for Langmuir—Blodgett films 26. which, because they are so thin, may prove impossible to use in parallel-plate form, but which can be routinely used with the high-sensitivity interdigi-tated-electrode approach provided by the CFT. 

S.K. Sharma, R. Singhal, B.D. Malhotra, N. Sehgal and A. Kumar, Lactose biosensor based on Langmuir-Blodgett films of poly(3-hexyl thiophene), Biosens. Bioelectron., 20(3) (2004a) 651-657. 

Scheme 11 Chemical structure of hairy rod" poly(L-glutamate)s used to obtain photochromic monolayers and Langmuir-Blodgett films. 81,85-91 ...

Poly(3-hexylthiophene)-based Langmuir-Blodgett film 7 x 10-7... 

Section II of this paper contains a description of the mechanism of NEXAFS spectroscopy, experimental setup and the types of information that can be obtained. Section III presents examples of work by others which serve as an important basis for the interpretation of our studies, and also several experiments on oriented polymer films and Langmuir-Blodgett films. Section IV describes a study of the chemical interaction that takes place when chromium metal is evaporated onto spun polymers, including polyimide. Section V describes the results of a study of poly(amic acid) films grown by epitaxy on clean surfaces of copper and chromium, and the effect of annealing to induce imidization. 

Tedeschi, C., Fontana, M. P., Pieroni, O., Dei, L., Wilde, J., Pearson, C., Petty, M. C., and Tanner, B. K., Deposition and Characterisation of Langmuir-Blodgett Films of an Azobenzene-containing Poly-L-lysine. Thin Solid Films 335,197 (1998). 

Hirata, Y, Nukanobu, K, Hara, M. (1992). Preparation of stable Langmuir-Blodgett film of photosynthetic bacterial reaction center from Rhodopseudomonas viridis using poly-L-lysine. Chem. Lett., 227-230. 

Pal, A.J. et ah. Polymeric light-emitting diodes from molecularly thin poly(3-hexy-Ithiophene) Langmuir-Blodgett films. A/)/)/. Phys. Lett. 69, 1137-1139, 1996. 

Systems that employed HREELS for interfacial-composition determinations included poly(ethylene oxide)-polystyrene diblock copolymer on Si wafers formaldehyde poly(oxymethylene) films on Cu(lOO) and Langmuir-Blodgett films of 4,4 -oxydianiline-pyromellitic dianhydride polyimide on Au and on highly ordered pyrolytic graphite. 

Ram M. K., Paddeu S., Carrara S., Maccioni E., and Nicolini C., Poly (ortho-anisidine) Langmuir-Blodgett films Fabrication and characterization, Langmuir, 13(10), 2760-2765, 1997. 

Stumpe J, Fischer T, Menzel H. 1996. Langmuir Blodgett films of photochromic poly glutamates, relation between photochemical modification and thermotropic properties. 

Note AFM measurements of electrostatic double-layer forces in aqueous electrolyte. Force measurements between surfactant layers are not included. They are discussed in the text. PEEK Poly(etheretherketone) EBfilm Langmuir-Blodgett film. 

Mattoso L. H. C., Mello S. V., Riul A Jn, Oliverira 0. N. Jn, and Faria R. M., nthesis and characterization of poly[o-phenetidineJ for the lubrication of Langmuir and Langmuir-Blodgett films. Thin Solid Films, 1994,244,714-717. 

Figure 13.4 Pressure-area isotherm of an Langmuir-Blodgett film of poly( 3-hexylthiophene)...

Recently, ultrathin films of poly(o-anisidine) and poly(ethoxyaniline) have been fabricated for application in nanotechnology [64-66]. Matsura and co-workers [67] have fabricated monolayers of 3-carotene using a Langmuir-Blodgett film technique together with the flow-orientation method. They have utilised XRD, UV-visible and FTIR techniques to elucidate the film-structure of P-carotene indicating that P-carotene orients perpendicular to the air-water interface. It was found that the films are, however, well-ordered both in the stacking direction and the in-plane direction. 

---