Molecular polymers

The emulsion polymerization of acrylamide yields a high-molecular polymer (with the molecular weight reaching 2.5-10 ), which can be easily dispersed in water to obtain water-in-oil type latex (containing 30-60% polymer). On prolonged storage, the emulsion exhibits lamination, but subsequent stirring allows easy redispersal of the product. 

Molecular Polymer Imprints (University of Texas) -DNA-Based Identification... 

The basic modem data describing the atomic stmcture of matter have been obtained by the using of diffraction methods - X-ray, neutron and electron diffraction. All three radiations are used not only for the stmcture analysis of various natural and synthetic crystals - inorganic, metallic, organic, biological crystals but also for the analysis of other condensed states of matter - quasicrystals, incommensurate phases, and partly disordered system, namely, for high-molecular polymers, liquid crystals, amorphous substances and liquids, and isolated molecules in vapours or gases. This tremendous... 

Polymerization, or conjugation, is the process in which toxic organic molecules undergo microbially mediated transformation by oxidative coupling reactions. In this case, a contaminant or its intermediate product(s) combines with itself or other organic molecules (e.g., xenobiotic residues, naturally occurring compounds) to form larger molecular polymers that can be incorporated in subsurface humic substances. 

As the laser beam can be focused to a small diameter, the Raman technique can be used to analyze materials as small as one micron in diameter. This technique has been often used with high performance fibers for composite applications in recent years. This technique is proven to be a powerful tool to probe the deformation behavior of high molecular polymer fibers (e.g. aramid and polyphenylene benzobisthiazole (PBT) fibers) at the molecular level (Robinson et al., 1986 Day et al., 1987). This work stems from the principle established earlier by Tuinstra and Koenig (1970) that the peak frequencies of the Raman-active bands of certain fibers are sensitive to the level of applied stress or strain. The rate of frequency shift is found to be proportional to the fiber modulus, which is a direct reflection of the high degree of stress experienced by the longitudinally oriented polymer chains in the stiff fibers. 

In contrast to the relatively slow step-reaction polymerizations discussed in Chapter 4, chain polymerizations are usually rapid, and the initiation species continues to propagate until termination. Thus, in the extreme case, a single initiation species could produce one high-molecular chain, leaving all of the other monomer molecules unchanged. In any case, the concentration of monomer, which is often a substituted vinyl compound, decreases continuously throughout the reaction. In contrast to stepwise polymerization, the first species produced in chain polymerizations is a high-molecular polymer. 

Loveless DM, Jeon SL, Craig SL. Chemoresponsive viscosity switching of a metaUo-supra-molecular polymer network near the percolation threshold. J Mater Chem 2007 17 56-61. 

Lohmeijer BGG, Schubert US. Water-soluble building blocks for terpyridine-containing supra-molecular polymers synthesis, complexation, and pH stability studies of poly(ethylene oxide) moieties. Macromol Chem Phys 2003 204 1072-1078. 

The mass spectroscopy clearly demonstrated that the oligomer molecule contained one butyl isopropenyl ketone unit at the chain end. The possibility that the ketone unit locates at the chain end of the polymer may be rejected because the low molecular polymer obtained in the lOmin polymerization also contained one ketone unit similarly to the high polymer. 

The AB monomer in structure 13 was polymerized in CHP in the presence of sodium hydride to yield low molecular polymer [50]. The rigid backbone apparently led to poor solubility and the polymer precipitated before high... 

Recall from Chapter 12 that polymers are large molecules made of repeating monomer units. Monosaccharides are the monomers that link to form the bio-molecular polymers called polysaccharides, which contain hundreds to thousands of monosaccharide units. Polysaccharides can be built from any type of mono-... 

Polynuclear inorganic compounds exist in a bewildering array of structural types, such as ionic solids, molecular polymers, extended assemblies of oxounions both of metals and nonmeinis, nonmetal chains and rings, bridged melui complexes, and homo- and hetero-nuclcar clusters. This section treats primarily the nomenclature of bridged metal complexes and homo- and hetero-nuclear dusters. 

The activated monomer should then initiate the polymerisation leading to the high molecular polymer containing no radio-activity. 

The synthesis of telechelic oligomers by oxidative cleavage has been extensively studied by numerous authors and Cheradame [117] reviewed the main reactions leading to telechelic polymers starting from high molecular polymers. As he showed, ozonolysis remains one of the preferred method in addition to Ruthenium tetroxide oxidation to obtain a-co functional oligomers. 

W. Trabesinger, A. Renn, B. Hecht, U. P. Wild, A. Montali, P. Smith and C. Weder, Single-molecule imaging revealing the deformation-induced formation of a molecular polymer blend, J. Phys. Chem. B 104, 5221 (2000). 

The flushed silanol is sampled to determine the solid residue, which should be 15-24%, and the gelatinisation time at 200 2 °C (the standard value is 0.5-60 minutes). After that, silanol is sent with vacuum through nutsch filter 8 into tank 9, which is an enameled apparatus with an agitator and a water vapour jacket, to distil the solvents. Before the distillation the product of hydrolytic condensation is held at 20-25 °C to eliminate traces of moisture. The distillation is conducted at 45-50 °C and a residual pressure of 105-80 GPa until the solid residue is 40-55%. Then the jacket of the tank is filled with water and the varnish is cooled to 20-25 °C. During the distillation of the solvents, the product of hydrolytic condensation is further condensed to form a higher-molecular polymer. 

Consequently, a molecular polymer chain bends forming coils and curves (see Figure 2.41), where neighboring chains interlace and entangle. The massive entanglement of the chain molecules in elastic materials is the origin of the big expansion exhibited by elastic materials [8],... 

In the case of the screw shearing element (Fig. 12.33), melt is drawn into shear gaps integrated at regular intervals in the screw tip, where it is subjected to a defined shearing field in which the higher-molecular polymer components are broken down. 

Yano K, Karubel (1999) Molecularly polymers for biosensor applications. Trends in Analytical Chemistry 18(3) 199-204... 

As a result of anionic polymerization of co-hydrolysis products at equimolar ratio of diorga-osiloxane and organosilsesquioxane units, 3D-polymers were synthesized. Polymerization of bicyc-lodimethylsiloxanes with various lengths of dimethylsiloxane chain between two cyclotetrasiloxane rings has given spatially cross-linked polymers [10] copolymerization of octamethylcyclotetra-siloxane with polyphenylsilsesquioxane leads to formation of soluble low-molecular polymers [11],... 

Thus, synthesis of cyclolinear organosiloxane and carbosiloxane copolymers with monocyclic frag-ments in the backbone, obtained in HFC, hydride polyaddition and polymerization reactions, are considered in this review. The above-shown data on high-molecular polymers with regular dispo-sition of cyclic fragment in the backbone are mainly synthesized by HFC and hydride polyaddition reactions. As for polymerization of bicyclosiloxanes, they are almost useless for high polymer syn-thesis. 

Olefin metathesis has become one of the most important large-scale technical processes for the manufacture of olefins in the petrochemical industry [123]. When cyclic olefins are used as substrates, high-molecular polymers, which are formed by the so-called ring-opening metathesis (ROM), have found applications as elastomers and plastics. Gas-phase studies on the mechanism of olefin metathesis had been confined to simple metal carbenes, for example [Mn=CH2]+, [Fe=CH2]+,and [Co=CH2]+ [124-127]. Most of the metatheses have been observed with deuterated ethylene. 

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