Functional groups, distribution

Noy, A., Frisbie, C.D., Rozsnyai, L.F., Wrighton, M.S. and Lieber, C.M., Chemical force microscopy — exploiting chemically modified tips to quantify adhesion, friction, and functional-group distributions in molecular assemblies. J. Am. Chem. Soc., 117(30), 7943-7951 (1995). 

The XAD-8 resin separation of hydrophobic and hydrophilic components of WSOM was also employed by Sannigrahi et al. (2006). The 13C-NMR results indicated that WSOM in urban atmospheric particles is mostly aliphatic in nature (-95% C mass) with major contributions from alkyl and oxygenated alkyls (-80%), carboxylic acid (-10%), and aromatic functional groups (-4%). The authors also found that urban aerosol WSOC are only qualitatively similar to aqueous humic material in terms of functional group distribution. 

This paper reports a study to verify the relationship between functional group distribution and thermal decomposition behavior. A Fourier transform infrared spectrometer (FTIR) has been employed to obtain quantitative infrared spectra of the coals, chars, and tars produced in the devolatilization experiments. The spectra have been deconvoluted by using a computerized spectral synthesis routine to obtain functional group distributions, which are compared to the model parameters. 

Up to now a broad variety of common organic and inorganic polymer systems have been used as a solid support for immobilized metal complex catalysts. During the first period of the development work the need for a tailor- made support to meet the requirements of this application became apparent, e. g., with respect to general and structural stability, nature and degree of functionalization, functional group distribution and density, and accessibility of the functional sites [17]. 

Compositional contrast, as well as modulus, can also be assessed by laterally resolved imaging of normal or lateral forces in the contact mode AFM. In the corresponding mapping [121] (see also Chap. 4), force-displacement curves are recorded for each pixel. Subsequently, the pull-off forces, as a measure for adhesion, and the indentation part of the loading curves, to extract/fit the elastic modulus, are evaluated for each pixel. In particular for adhesion mapping, the use of chemically functionalized AFM probe tips [122], has been shown to be a suitable approach to map chemical composition and functional group distributions down to the sub-50 nm scale [123]. The mapping of adhesion, friction, and surface mechanical properties will be treated in more detail in Chap. 4. 

Chap. 2, altered surface tensions of surface-treated polymers are directly accessible. In addition, laterally resolved maps of adhesive interactions are useful to investigate heterogeneous samples, such as multicomponent systems, or to record local functional group distributions. For quantitative AFM work, calibration procedures for the cantilever spring constant and the AFM detection system become important. In addition, the use of modified tips will be discussed as a means to enhance the applicability of AFM for chemically sensitive imaging. 

The measurement of friction forces, in particular on multicomponent systems, may provide a rapid, qualitative insight into the distribution of the components and may be useful to map local functional group distributions. For quantitative friction mode AFM work, calibration procedures for the lateral spring constant and the AFM detection system become crucial. These calibration approaches are more demanding than the one described in Sect. 4.1, but because of recent progress in calibration standard development can be successfully tackled. 

The properties of filled materials are eritieally dependent on the interphase between the filler and the matrix polymer. The type of interphase depends on the character of the interaction which may be either a physical force or a chemical reaction. Both types of interaction contribute to the reinforcement of polymeric materials. Formation of chemical bonds in filled materials generates much of their physical properties. An interfacial bond improves interlaminar adhesion, delamination resistance, fatigue resistance, and corrosion resistance. These properties must be considered in the design of filled materials, composites, and in tailoring the properties of the final product. Other consequences of filler reactivity can be explained based on the properties of monodisperse inorganic materials having small particle sizes. The controlled shape, size and functional group distribution of these materials develop a controlled, ordered structure in the material. The filler surface acts as a template for interface formation which allows the reactivity of the filler surface to come into play. Here are examples ... 

Fig. 7. Two primary modes of organic (functional) group distribution in mesoporous frameworks. ...

Mezey PG, Fukui K, Arimoto S, Taylor K. Polyhedral shapes of functional group distributions in biomolecules and related similarity measures. Int J Quantum Chem 1998 66 99-105. 

A prerequisite for building up cyclic carbosilanes with functional groups is the preparation of linear carbosilanes with more than two functional groups distributed in the desired way on different Si atoms. A trisilacyclo-hexane with two Si functional groups has been prepared according to the scheme on page 382 (42). 

Free-radical grafting is a preferred way to add functionality to polyolefins, e.g. reaction with maleic anhy de. Amine functionalized polymers can be obtained by further derivatization of carboxylic anhydride functionalized polyolefin with amines. Polymeric materials containing amino groups are important because of the chemical versatility of the amino function. Although such procedures are useful, they lack control over molecular weight and functional-group distribution in the polymer. 

Extensive works conducted by different authors utilizing GC and GC/MS sometimes lead to different results which indicate tfui difficulties of carrying out accurate detailed analysis of the chemical constitupyrolysis oils. Examples of incomplete or even contradictory results can be found in the literature (3 4) and this paper in the analysis of vacuum pyrolysis oils. Other researchers have studied the functional group distribution in l>yrolysis oil (8), Althoiigh those techniques are long and tedious, they will lead to useful information about wood oil chemistry. 

As described in Chap. 10, the preparation of porous films by using this approach is simple, fast, and does not require the removal of any template. In addition, this technique can be used with different materials [10, 98,106] including mixtures of polymers [107-110] and can produce films with controlled pore dimensions [101, 111-114] and precise functional group distribution [107, 114-120]. Recent reviews have been published on this topic [9, 10, 103, 121, 122]. 

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