Lateral order

Monolayers of alkanetliiols adsorbed on gold, prepared by immersing tire substrate into solution, have been characterized by a large number of different surface analytical teclmiques. The lateral order in such layers has been investigated using electron [1431, helium [144, 1451 and x-ray [146, 1471 diffraction, as well as witli scanning probe microscopies [122, 1481. Infonnation about tire orientation of tire alkyl chains has been obtained by ellipsometry [149], infrared (IR) spectroscopy [150, 151] and NEXAFS [152]. 

Differently from the cases of ETFE, PTFE, 1,4-trans-polybutadiene, and PE, in the mesomorphic form of i-PP it is believed that there is a nearly complete conformational order, in the chains packed with parallel axes, (intrachain long range 3-D order) and only short-range lateral order in the positioning of the chain axes [60, 61]. 

The third category, shown in Fig. 2d, results when all of the long molecules or microcrystallites are aligned along the fiber axis, but they aggregate with little lateral ordering. This assembly, called an oriented fiber, diffracts to produce a series of layer lines that are perpendicular to the fiber axis. The intensity is nonuni-... 

In addition to the surface/interface selectivity, IR-Visible SFG spectroscopy provides a number of attractive features since it is a coherent process (i) Detection efficiency is very high because the angle of emission of SFG light is strictly determined by the momentum conservation of the two incident beams, together with the fact that SFG can be detected by a photomultiplier (PMT) or CCD, which are the most efficient light detectors, because the SFG beam is in the visible region, (ii) The polarization feature that NLO intrinsically provides enables us to obtain information about a conformational and lateral order of adsorbed molecules on a flat surface, which cannot be obtained by traditional vibrational spectroscopy [29-32]. (iii) A pump and SFG probe measurement can be used for an ultra-fast dynamics study with a time-resolution determined by the incident laser pulses [33-37]. (iv) As a photon-in/photon-out method, SFG is applicable to essentially any system as long as one side of the interface is optically transparent. 

The technique of fluorescence spectral measurements has become very sensitive over the past decade. In order to obtain more information on the surface monolayers, a new method based on fluorescence was developed. It consisted of placing the monolayer trough on the stage of an epifluorescence microscope, with doped low concentration of fluorescent lipid probe. Later, ordered solid-liquid coexistence at the water-air interface and on solid substrates were reported. The theory of domain shapes has been extensively described by this method. 

The use of Cl to represent the percentage of the crystalline component is unjustified among such a diversity of cellulosic materials, whose lignin components vary from 0 to about 30%. Cl, as used here, is not intended to represent the proportion of the crystalline component. Rather, Cl provides a means of quantifying the characteristics of the x-ray diffraction patterns. When applied to a set of similar samples, Cl is a convenient measure of the degree of lateral order. 

Thus, further experiments were performed with two hydrolytically degraded linters powders subsequently disintegrated to different particle sizes (Filtrak, FNA and FND, VEB Spezialpapierfabrik Niederschlag, GDR), the lateral order of these samples being varied by liquid ammonia treatment or by mercerization with 18% aqueous NaOH. A posthydrolysis of these samples with aqueous acid (5% HC1, 2 hr, 100°C) resulted in changes in DP and in residue as indicated in Table IX and as to be expected from previous publications (11,16). 

A common feature of vapor-phase thermohydrolysis, liquid-phase acid hydrolysis, and enzymatic hydrolysis of cellulose is a significant influence of lateral order on the rate of chain cleavage, the DP finally reached, and weight loss. But with regard to this influence of the physical structure of cellulose, there also exist remarkable differences between these three modes of hydrolytic degradation. 

Weisel, J. W. (1986a). The electron microscope band pattern of human fibrin Various stains, lateral order, and carbohydrate localization. /. Utirastruct. Mol. Struct. Res. 96, 176-188. 

The outlined problems correspond to the most typical system where three phases, e.g. liquid, gas and solid, are brought in contact. Additional wetting geometries can occur when the liquid phase consists of two subphases, e.g. mixture of incompatible polymer liquids, and/or the substrate surface exhibits variations in chemical composition. In these cases, the interfacial interactions will strongly interfere with the phase separation inside the film. Laterally ordered polymer films might be formed due to the preferential wetting of the patterned substrate by one of the liquid phases. 

Recently, chemically patterned surfaces have attracted a lot of attention due to their potential use as templates for lateral ordering of polymer films. On a micrometer scale, liquid dewets such surfaces and segregates on surface areas which exhibit preferential interaction with the liquid [360,361 ]. A few successful attempts have been made to transfer a lateral variation in surface energy into a composition pattern in the polymer film [16,362,363]. Figure 39a shows a laterally patterned structure which consist of periodic stripes of alternating PVP and PS domains. One of the domains, e.g. PVP, could be removed by dissolution in a... 

Figure 17. (a) Squares 29a deposited onto the anion-covered surface. Quite many oligomer chains can be seen due to the acidic conditions of sample preparation 20.5 nm x 20.5 nm. (b) Lateral ordering of squares 29a, 7.6 nm x 7.6 nm.(c) Long-range order of squares 29a to yield large perfect domains under optimized sample preparation conditions (see text) 35.6 nm x 35.6 nm. 

Coleman, L.B. Fiske, T.G. Stroeve, P. Coelho, M.A.N. Dong, S. Ringsdorf, H. Schneider, J. Thin Solid Films. 1989,178. 227. Swalen, J.D. Rabolt, J.F. Characterization of Orientation and Lateral Order in Thin Films by Fourier Transform Infrared Spectroscopy , in Fourier Transform Infrared Spectroscopy. 1905,4,283. 

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