Polymer surface, chemical modification

The conventional spectrometer with a dispersive prism or grating has been largely superseded by the Fourier transform (FTIR) technique. This uses a moving mirror in an interferometer to produce an optical transform of the infrared signal. Numerical Fourier analysis gives the relation of intensity and frequency, that is, the IR spectrum. FTIR can be used to analyze gases, liquids and solids with minimal preparation in short times. FTIR has been applied to the study of many systems, including adsorption on polymer surfaces, chemical modification and irradiation of polymers and oxidation of rubbers [36]. The application of infrared spectroscopy to the study of polymers has been reviewed by Bower and Maddams [35]. 

Figure 3. Functionalization of CNTs (a) non-covalent interacions with polymers and biomolecules (b) covalent surface chemical modification (end-functionalization and side-wall functionalization).

Polymer surface modifications are omnipresent in applications where the surface properties of materials with favorable bulk properties are insufficient. By altering the surface characteristics using physical or chemical modification the desired surface properties may be achieved. Such treatments are required e.g. to enhance printability of films, the adhesion of paints, metal or other coatings, biocompatibility, protein resistances/reduced biofouling, etc. The diverse approaches met in practice include, among others, wet chemical and gas phase chemistry, plasma or corona, UV/ozone and flame treatments. In most cases surface chemical modification reactions take place that alter the surface energy in a desired way. For example,... 

In many applications and formulations, WSPs with surface-active properties are desirable. These properties are imparted to a polymer by chemical modification of the hydrophilic WSP with appropriate hydrophobic substituents. Examples of commercially available surface-active WSPs based on cellulose include its methyl, hydroxypropyl, and methylhydroxypropyl derivatives. 

As effective as these surface modification processes might be, they present limitations in terms of the extent to which the surfaces of polymers can be modified. Plasma-induced grafting offers another method by which chemical functional groups can be incorporated. In this process, free radicals are generated on the surface of a polymer through the use of an inert gas plasma. Because of the nonreactive nature of the inert gas plasma, surface chemical modification of the polymer does not occur. If the polymer surface that has been... 

The modification of polymer surfaces both in terms of structure and functionality is a subject that has been evidenced to be of theoretical and practical interest [ 1,2]. In this sense, a large amount of literature has been published describing a wide variety of surface chemical modification approaches such as flame or corona treatments, chemical reactions (in solution), plasma or UV treatments or the application of polymer coatings among others [3-11],... 

Excluding the use of an aqueous polymer dispersion, or latex, an alternative way to process nonpolar polymer nanocomposites reinforced with cellulose nanocrystals consists of their dispersion in an adequate (with regard to matrix) organic medium. Coating with a surfactant or a surface chemical modification of the nanoparticles can be considered. The global objective is to reduce their surface energy in order to improve their dispersibUity/compatibility with nonpolar media. 

To improve the adhesion between natural fiber and polymer matrix, chemical modification of natural fibers was investigated by a number of researchers. The mechanism and utilization of selected chemical treatments is discussed in this section. There are many different methods to improve the interfacial adhesion between fiber and matrix by modifying fiber surface such as acetylation, benzoyla-tion, acrylation, permanganate, and isocyanate treatment. These treatments are described in detail by Kalia et al. [69]. 

In this contribution, we intend to introduce recent work dedicated to polymer-clay nanocomposites based on sepiolite and palygorskite fibrous silicates. We will consider as a priority the role of the interface between the mineral surface and the polymer matrix. In fact, this type of clay is markedly hydrophilic because their surface is covered by hydroxyl groups, mainly silanol groups (=Si-OH) [17, 22], and therefore they are compatible with many polar polymers. However, chemical modification of the silicate surface could be necessary for adjusting their... 

First, the stability of these polymer materials is very important for their practical use and processing. Assessment of surface chemical modification of rubber after aging treatment is, by example, primordial for pneumatic manufacturing. Similar to conventional methods, LA-MS is allowed to evaluate and follow the oxidation effects on model polymers such as polybutadiene (PB), polystyrene (PS), and styrene butadiene rubber (SBR) by both detection and identification of the degradation products. The thermooxidative stability of SBR has been then investigated. 

Lee, S., Spencer, NT). Aqueous lubrication of polymers influence of surface chemical modification. Tribol. hit. 38, 922-930 (2005)... 

The fundamental modification of polymer surface chemical nature that suffered friction was experimentally established by NMR and IR spectroscopy. Thus, in the case of polyethylene, natural rub-... 

In modem theory of friction, 90% of the total friction is believed to come from interatomic adhesion between two surfaces [8], If the interatomic adhesion is weakened, the friction force could be reduced. If water, the most abundant fluid in the body, easily wets the polymer surface and creates a thin layer between two surfaces to eliminate soUd/solid contact, the friction force could be significantly reduced. Therefore, a general approach of friction reduction is to increase the surface hydrophiUcity of polyurethane by coating or by surface chemical modification [9-22]. 

When using nonaqueous systems, the processes of nonpolar polymer nanocomposites reinforced with polysaccharide nanoparticles involve dispersion in the organic medium of nanoparticles, coating with a surfactant, or surface chemical modification of the nanoparticles to reduce their surface energy and to increase dispersibility in nonpolar media. The decrease of surface energy ensures dispersion of nanoparticles in organic liquids with low polarity. 

The characteristics of composite membranes depend not only on the type of metal oxide, but also on surface area, size, concentration and surface chemical modification of the metal oxide, and on the type of polymer matrix. The primary method for characterising membranes is to compare the current-voltage response of the cell as a function of membrane chemical characteristics and cell humidity/temperature. 

Additives. Because of their versatility, imparted via chemical modification, the appHcations of ethyleneimine encompass the entire additive sector. The addition of PEI to PVC plastisols increases the adhesion of the coatings by selective adsorption at the substrate surface (410). PEI derivatives are also used as adhesion promoters in paper coating (411). The adducts formed from fatty alcohol epoxides and PEI are used as dispersants and emulsifiers (412). They are able to control the viscosity of dispersions, and thus faciHtate transport in pipe systems (413). Eatty acid derivatives of PEI are even able to control the viscosity of pigment dispersions (414). The high nitrogen content of PEIs has a flame-retardant effect. This property is used, in combination with phosphoms compounds, for providing wood panels (415), ceUulose (416), or polymer blends (417,418) with a flame-retardant finish. 

Chemically modified polymers have been used to determine polar compounds in water samples (37, 71). Chemical modification involves introducing a polar group into polymeric resins. These give higher recoveries than their unmodified analogues for polar analytes. This is due to an increase in surface polarity which enables the aqueous sample to make better contact with the surface of the resin (35). 

UV irradiation on a polymer surface produces chemical modification as well as wettability and bondability improvement. It causes chain scission and oxidation on polymer surfaces. -iven in the presence of an inert gas [45]. Carbonyls are found to be introduced onto polyethylenes on UV irradiation. Sivram et al. [46] have used photochemical treatments for surface modification of polymers. They have generated surfaces of vaying surface energies by simple organic reactions. 

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