Polymer condensation-type

In addition to the solvent soluble toners, alkah water-soluble toners have been produced. These types include WST produced by Day-Glo and Aquabest produced by Radiant Color. These toners are dissolved ia water which contains a portion of ammonia and, if necessary, some isopropyl alcohol. These toners can be used as binders or additional binders and other additives can be added to give the ink the desired properties. These toners are condensation-type polymers other than the formaldehyde types. 

The first strategies to random hyperbranched polymers involved exclusively step-growth polymerizations. This limited the potential applications for these architectures to areas where only condensation-type polymers are acceptable. Frechet et al. [21] presented the first example of a hyperbranched vinyl polymerization in 1995, ] initiating the birth of a second generation of hyperbranched... 

Properties and Uses of Some Important Synthetic Condensation-Type Polymers... 

Liquid crystallinity can be attained in polymers of various polymer architectures, allowing the chemist to combine properties of macromolecules with the anisotropic properties of LC-phases. Mesogenic imits can be introduced into a polymer chain in different ways, as outhned in Fig. 1. For thermotropic LC systems, the LC-active units can be connected directly to each other in a condensation-type polymer to form the main chain ( main chain liquid crystalline polymers , MCLCPs) or they can be attached to the main chain as side chains ( side chain liquid crystalline polymers , SCLCPs). Calamitic (rod-Uke) as well as discotic mesogens have successfully been incorporated into polymers. Lyotropic LC-systems can also be formed by macromolecides. Amphiphihc block copolymers show this behavior when they have well-defined block structures with narrow molecular weight distributions. 

Law and Johnson (22, 29) published the most detailed analysis of the role of the polymer chemical and physical properties on the sensitivity and performance of dye-polymer solutions. Their key results are collected and summarized in Table 7.3. They investigated addition- and condensation-type polymers and probed the effect of physical properties such as glass transition... 

Not all of the approaches discussed in this section are equally developed. The priority is given to the reduction techniques. The role of the dispersive phase is mostly played by carbon-chain polymers and less often, by condensation-type polymers. The immobilization of nanoparticles is nearly always accompanied by chemical interactions of the particles formed with the matrix, in contrast to mechanical mixtures of metals with polymers. Further developments in the preparation of polymer-immobilized nanoparticles have been documented. 

Self-Condensing Vinyl Polymerization. The first hyperhranched vinyl polymer was presented in 1995 (48) and this marked the birth of the second generation of hyperhranched polymers. Hitherto, exclusively step-growth polymerization had been utilized to accomplish hyperhranched pol5miers. This had, of course, also limited the potential applications to areas where condensation-type polymers are acceptable. 

Thermally-assisted hydrolysis and methylation (THM) using organic alkaline reagents is widely utilised for reliable and informative characterisation of various condensation-type polymers that are often intractable for the conventional pyrolysis techniques [619]. Wang [618] has extended the derivatisation concept and distinguishes pre-pyrolysis and post-pyrolysis (i.e. pre-column ) derivatisation reactions. The purpose of pre-pyrolysis derivatisation is to secure a favourable thermal degradation pathway during pyrolysis. 

Polyamide (substrate) A condensation-type polymer. Polyamides can retain large amounts of water. Example Nylon M. 

By means of a ring-opening polymerization of the condensation type Vlasov et al. [50] synthesized polypeptide based MAIs with azo groups in the polymeric backbone. The method is based on the reaction of a hydracide derivative of AIBN and a N-carboxy anhydride. Containing one central azo group in the polymer main chain, the polymeric azo initiator was used for initiating block copolymerizations of styrene and various methacrylamides. 

Since Carothers introduced the distinction between condensation and addition polymers based on the composition relationship between monomer and structural unit, a number of examples of polymerization processes have been found which formally resemble the condensation type but which proceed without evolution of a by-product. For example, a glycol and a diisocyanate react intermolecularly as follows ... 

Several combinatorial approaches to the discovery of transition metal based catalysts for olefin polymerization have been described. In one study Brookhart-type polymer-bound Ni- and Pd-(l,2-diimine) complexes were prepared and used in ethylene polymerization (Scheme 3).60,61 A resin-bound diketone was condensed with 48 commercially available aminoarenes having different steric properties. The library was then split into 48 nickel and 48 palladium complexes by reaction with [NiBr2(dme)] and [PdClMe(COD)], respectively, all 96 pre-catalysts being spatially addressable. 

Although the first examples of hyperbranched polymers proposed by Flory involved condensation-type polymerization strategies, the first well-characterized hyperbranched example involved the ring-opening polymerization of 2-carboxylic-2-oxazoline derivatives. As early as 1988, Odian and Tomalia [2] reported the ring-opening polymerization of these derivatives to form random... 

Nearly all synthetic polymers are synthesized by the polymerization or copolymerization of different "monomers." The chain growth process may involve the addition chain reactions of unsaturated small molecules, condensation reactions, or ringopening chain-coupling processes. In conventional polymer chemistry, the synthesis of a new polymer requires the use of a new monomer. This approach is often unsatisfactory for Inorganic systems, where relatively few monomers or cyclic oligomers can be Induced to polymerize, at least under conditions that have been studied to date. The main exception to this rule is the condensation-type growth that occurs with inorganic dl-hydroxy acids. 

While condensation polymers account for only a modest fraction of all synthetic polymers, most natural polymers are of the condensation type. The first all-synthetic polymer, Bakelite, was produced by the stepwise polycondensation of phenol and formaldehyde. 

Further intramolecular reaction of the poly(phenylene)-type polymer leads to more condensed polymers. Tour synthesized polymer 84 bearing a carbonyl moiety and a protected amino group in the phenylene rings by the reaction of boronate 83 and a dibromobenzene monomer. The polymerization takes place in the presence of a palladium catalyst in DME-H2O at 85 °C to give 84 that showed 3/n = 9850-28400 = 1.85-3.70) in 63-97% yields. The resulting polymer 84 is... 

According to these earlier studies, a reaction mechanism involving diradical intermediates of the type (SiF2) (where n = 1, 2, 3, etc.) was established (70, 73, 80). This idea is particularly attractive if one considers the facts that in co-condensation reactions polymers are the major products obtained, and that volatile products of co-condensation reactions often contain (SiF2) units with n > 1. The earlier ESR study also supported this idea (52). 

More specifically, the acyclic alkenes is defined gation, condensation-type polymerization, where the term condensation-type arises from the liberation of a by-product that advances the reaction. The other possibility for step polymerization is addition-type, where the resulting polymer linkage is an adduct of the two monomers, and no atoms are lost (e g. polyurethanes). 

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