Some biopolymers

Crosslinking using reactions of multifunctional reagents with side groups of polymers is most frequently applied to PVA, some biopolymers containing OH-groups, partly hydrolyzed PAAm, polyamines, and other polymers. These reactions are reviewed in Ref. [52],... 

Owing to the above reasons, some biopolymers have been used directly or after modification, to replace the conventional fillers leading to partial biodegradation. A number of studies have been carried out with an aim to maximize the proportion of renewable resources used while retaining acceptable material properties. 

Molecules can be small, like CH4, large, or very large, like some biopolymers with molecular weights of millions of daltons. They can be organic, inorganic, polar, apolar, etc. Mass spectrometry can study all of them. However, one ionization technique cannot ionize all kinds of molecules but different ionization techniques are now available. Their choice is based on the chemico-physical properties of the molecule, such as molecular weight, polarity, thermal stability, etc. 

Most polymers are nontoxic under the normal and intended use. (Some biopolymers, such as snake venom, should not be dealt with except under very controlled conditions.) Most of the additives employed are also relatively nontoxic. Even so, care should be exercised when dealing with many of the monomers of synthetic polymers and when dealing with polymeric materials under extreme conditions such as in commercial and domestic fires. 

It is probable that a similar pathway of PolyP synthesis which is related to the biosynthesis of some biopolymers may exist in bacteria. Undecaprenyl diphosphate, which could be involved in this pathway, is found in bacteria. 

To obtain other pHs, a listing of common buffers used in my laboratory is given in Table 1. Phosphate is an excellent buffer over a wide range of pHs. It binds to the capillary wall and generally produces reproducible electroosmotic flow. Should phosphate bind to the solute, a wall effect is produced that lowers efficiency [12], This tends to occur with some biopolymers. If the effect is noted, select an alternative buffer. 

For small neutral organic compounds, reversed-phase chromatography usually provides much better efficiency than lEC. However, a mixed-mode separation mechanism on ion-exchange columns can offer a unique selectivity for the separation of some biopolymers such as peptides or proteins [73). 

Table 1-2 Examples of Magnitudes of Intrinsic Viscosity [ij] and Average Molecular Weight (A/) of Some Biopolymers...

The modification and general improvement of properties caused by the addition of such compounds is a very interesting issue to be studied with a wide range of analytical techniques. Their identification and eventual determination is usually carried out by chromatographic techniques coupled to a variety of detection systems, most often mass spectrometry (MS). This powerful hyphenated technique, extensively used in many different analyses, combines the separation capabilities of chromatographic techniques with the potential use of MS to elucidate complicated structures and to identify many chemical compounds with low limits of detection and high sensitivities. The use of MS also permits the simultaneous detection and determination of several of those additives in a single analysis. This is especially valuable when only a small quantity of material is available, which is the usual case in some biopolymer formulations. 

Soft ionization methods produce few fragments under relatively mild conditions. The ionization method that has received the most attention in terms of its applicability to protein and DNA analysis is the electrospray ionization (ES) technique. This is a soft method that is capable of generating molecular ions from biological macromolecules present in solution. Table 12.3 gives examples of the charge and m/z ranges that have been observed with some biopolymer species in electrospray ionization mass spectrometers. 

FIGURE 9. Average elemental composition of humic acids and stable residues from marine and terrestrial organic matter, compared to average elemental composition of some biopolymers. 

The AFM method was used to study some biopolymers, such as DNA on mica, etc. however, the resolution of AFM is known to be limited by the sharpness of the tip, and interpretation of the image has been related to the geometry of the tips. For example, due to the finite radius of the tip, AFM images of DNA are on average seven times broader than the known 2-nm (20 A) width of DNA. This kind of result requires the description of the resolution of AFM images, especially when comparing images of AFM with electron microscopy. 

Radiation-induced crosslinking of acetylene impregnated polymers — Enhanced crosslinking and reduction in chain scission are found in the amorphous regions of polycrystalline polyesters, when they are irradiated in the presence of acetylene [7], Similar effects have been observed in the crosslinking of some biopolymers which are otherwise radiation degradable. 

Synthetic macromolecules do not in general exhibit relatively fixed conformations as do some biopolymers. Rather, each polymer molecule in solution is bombarded by the solvent molecules and, as a result of the rotations about bonds, scans through the huge range of accessible conformations. The chains assume neither their fully extended nor their fully compressed conformations since these are both highly ordered microstates. Instead, they adopt on average an intermediate conformation, usually referred to as a random coil 62... 

The porphyrin skeleton is essentially hydrophobic this feature may be an important factor affecting the preferential acciunulation in cellular hydrophobic loci since such molecules must be able to get into cells by crossing Upid membranes. That brings insolubility in physiological fluids to overcome this fact adequate formulations have to be used, such as incorporation into hpo-somes, biopolymers and cyclodextrins [43-45]. 

Table 6.6 Potential applications of some biopolymers to cotton textiles for flame retardancy... 

Piezoelectricity, pyroelectricity, and ferroelectricity is hardly confined to synthetic polymers. Some biopolymers also possess these properties, and scientists study them to understand how nature exploits these properties. The earliest studies of biopolymer piezoelectricity, for example, go back to 1960s when Morris Shamos and Leroy Lavine (with Michael Morris) studied bone piezoelectricity [39] and later postulated piezoelectricity as a fundamental property of tissues of biological origins [40], In 1968, RNA ferroelectricity was demonstrated by Stanford and Lorey [41]. However, the scientific interest in these properties of biological molecules was dwarfed by the interest in other materials. In 1999 Sidney Lang [42] indicated that compared to thousands of publications on piezoelectric, pyroelectric, and ferroelectric materials, only less than 100 of them were biologically related. 

Ferroelectricity is a requirement for some biopolymers for their biological function. Microtubules which hold the cell structurally intact are a good example. These biostructures consist of identical a and (3 tubulin proteins which have permanent dipole moments. Since cells utilize microtubules... 

When all the polymer molecules have the same degree of polymerization or, in other words, when all polymer molecules contain equal numbers of monomers, the system is called homodisperse or monodisperse. When the degree of polymerization varies among the polymer population, it is called heterodisperse or polydis-perse. Synthetic polymers and some biopolymers (e.g., most polysaccharides) are more often than not heterodisperse, whereas other biopolymers such as proteins and nucleic acids are usually homodisperse. 

There are various ways to classify polymers. A simple way is to distinguish polymers with respect to their origin in synthetic and natural polymers. Natural polymeric materials such as shellac, cellulose, and natural rubber have been used for centuries. Natural polymers are a class of polymers derived from renewable biomass sources, such as plants, vegetable oil, com starch, pea starch. Generally, natural polymers (or biopolymers) are used after modification reactions. Some biopolymers are designed to biodegrade. Table 2.1.1 and Fig. 2.1.1 give examples of natural polymers and modified natural polymers. 

In this section we outline the publications and selected features of neutral thermoresponsive homopolymers exhibiting the LCST phase separation in aqueous media, see Tables 2 and 3, and also those whose properties drastically change upon cooling, see Table 4. We will utilize the definitions for transition temperatures used by the authors. Due to the huge number of polymers of this type, some biopolymers such as polysaccharides will not be described here. 

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