Organic polymers studies

The results of this study clearly show the complex dependence of the flocculation process on polymer dosage and charge density. It is seen that the form of dependence varies markedly among the responses monitored. In addition to the factors studied here, it can also be expected to depend upon several other physicochemical conditions of the system, including the type of mixing. The final state of flocculation achieved by a mineral/polymer system will depend upon many interactions in the system as determined by various chemical and hydrodynamic properties of the particles, polymer, dissolved organics and the fluids. 

The periodontal pocket is another site for drug delivery in the oral cavity. Needleman et al. [46] investigated three mucoadhesive polymers (cationic chitosan, anionic xanthan gum, neutral polyethylene oxide) in vitro, using organ cultures, and in vivo in patients on their periodontal and oral mucosa. Of the polymers studied, chitosan displayed the longest adhesion in vitro and on the periodontal pockets, and the shortest adhesion on oral mucosa. 

In the following section, we will show how radiation chemical reactions are useful for the molecular design of functional organic materials by taking our recent studies on next-generation resist polymers and organic semiconductors as examples. 

Recently most of the polymer studies, not only ionic but radical polymerization, too, have been carried out in organic media. However, polymer chemists engaging in electropolymeiization have come upon many difficult problems when they introduced the electrolytic processes to their own field of chemistry, because there has been little knowledge of the electrochemistry in organic media free from water. The problems were how to choose organic solvents and supporting electrolytes which would not affect the polymerization, electrodes and cells to be used in the electropolymerization. 

Whether or not the stereogenic tertiary carbon atoms in isotactic and syndiotactic polypropylene are chirotopic depends on the model chosen for their representation [16]. Stereochemical analysis, which followed Natta s discovery, involved two models of the polymer chain. Stereoregular polymers were considered, on the one hand, as the extrapolation towards high molecular weights of well-studied organic molecules, e.g. such as trihydroxyglutaric acid ... 

Using Near-Edge Soft X-ray Absorption Spectroscopy To Study Organic Polymers and Metal—Polymer Interactions... 

As Th-FFF is the technique of choice for synthetic polymers in organic solvents, there are many studies reported in the literature. Th-FFF has been found applicable to virtually every type of lipophilic polymer in the range M=104-107 g/mol using AT-10-100 K,but only to a very limited amount of hydrophilic polymers where Fl-FFF has its traditional strengths. Exceptions include polyfvinyl pyrro-lidone) and polyfethylene glycol) [222]. 

The above-mentioned reactions have not been sufficiently studied so far, although they are of considerable interest, as they could yield thermostable polymers or organic semiconductors. With radical initiators, only oligomers are always formed, with a large content of cycles. Most authors assume that the reluctance of acetylenes to yield long chains is connected with the attenuation of centre reactivity, i.e. with inter- and intramolecular delocalization of the unpaired electron in the growing macroradical [79]. 

The polarities of binary solvent mixtures with limited mutual miscibility such as zz-BuOH/H20 and c-CeH /DMF [191] as well as of solid polymer mixtures (organic glasses) [195] have also been studied using solvatochromic probes such as the betaine dye (44). 

The development of the sources led to studies in polymers, solids, organic systems, which were too numerous to mention. One only needs to look at the chapters by Dole, Willard and others in the book on the history of radiation chemistry to find the wide range of chemical systems that could be studied. ... 

Hugi-Cleary D, Helm L, Merbach AE (1985) Variable temperature and variable pressure NMR study of water exchange of hexaquaaluminum(III). Helv Chim Acta 68 545-554 Hunter D, Ross DS (1991) Evidence for a phytotoxic hydroxy-aluminum polymer in organic soil horizons. Science 251 1056-1058... 

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