Polyaddition method

Chemical syntheses of structures of 7 and 2, based on the polyaddition method, were elaborated by Michelson ° and Baddiley et al. 2), respectively. 

In conclusion, furan and 2-alkylfurans can be polymerized only by acidic initiators or by y-radiation because the other standard methods of polyaddition fail to induce a chain-propagation reaction. 

More recently, Mullen et al., have worked out very efficient methods for generating highly arylated, branched oligophenylene- and related oligoarylene derivatives, following different synthetic procedures based on polyaddition reactions in the key step. 

The method of migration polymerization (polyaddition reaction) finds extensive application in the production of silicon-, germanium- and tin-containing hetero-organic polymers 97). 

Next we consider the dispersion polymerization by polyaddition. In a typical method to prepare polyimide particles, polyamic acid solution is first obtained by coupling of pyromellitic dianhydride and oxy-dianiline, and then by heating the solution. The condensation reaction on heating causes crystallization of polyimide in a spherical form (Fig. 11.2.5, left) (33). However, on the contrary to this conventional method, polyamic acid microspheres could be obtained by dispersion polymerization if an appropriate medium is chosen (34). When a solvent that has a solubility parameter around 17 Mpa is used, submicrometer-sized monodisperse polyamic acid parti-... 

Michelson first applied polycondensation (polyaddition) to prepare the TA-like backbones 1). This method introduces the reactive pyrophosphate intermediate ... 

The ROP of lactones, cyclic diesters (lactides and glycolides), and cyclic ket-ene acetals is an alternative method, which has been successfully employed to yield high molecular mass polymers under relatively mild conditions. This polyaddition reaction can be carried out with no or very limited side-reactions, and this makes it possible to control properties like molecular weight and molecular weight distribution (MWD). Both polycondensation and ROP have been reported in the literature for the synthesis of polyesters. 

A recently developed application of this method in the field of polymers involves the synthesis of three geometrical isomers by polyaddition of diethynyl compounds, based on transition-metal-catalyzed dimerization of arylacetylenes [5], This reaction goes highly regio- and stereoselectively and is controlled by appropriate choice of the catalyst, affording polymers with ( )-, (Z)- and gem-vinylene linkages with selectivity over 92 %, as illustrated in Scheme 12. 

Reviewed in this paper is synthesis of cyclolinear carbosiloxane copolymers with regular disposition of mono-, bi- and tricyclic fragments in dimethylsiloxane backbone using hydride polyaddition reaction as the method for synthesis of polymers. 

Synthesis of carboorganosiloxane copolymers and polymers is based on hydride polyaddition of organohydrosiloxanes to organoalkenyl silanes [69], Recently, this reaction is of great interest in the field of obtaining complex monomers [70], as well as in the field of study of addition mechanisms on various Pt, Pd, Co and metal carbonyl catalysts [71-74] and specificity of actions of one or other catalytic systems [75], Besides carboorganosiloxane oligomers and linear polymers, other compo-unds were also synthesized by this method [76 -78],... 

The borderline between chain and step polyadditions has never been strictly defined. In fact it is mobile, and if the molar mass change with time is accepted as a criterion, this borderline is expected to change with the development of experimental methods. Polymerizations proceeding on the multiple bonds of monomers or by opening of their rings need not be classified in this way ... 

In addition to the repeat unit sequence, another area of current interest in polymer structural control (Fig. 1) may be the spatial or three-dimensional shapes of macromolecules. In fact, the recent development of star [181-184] and graft [185] polymers, as well as starburst dendrimers [126], arborols [186,187], and related multibranched or multiarmed polymers of unique and controlled topology, has been eliciting active interest among polymer scientists. In this section, let us consider the following macromolecules of unique topology for which living cationic polymerizations offers convenient synthetic methods that differ from the stepwise syntheses (polycondensation and polyaddition) [126,186,187]. 

Tn addition, there ore nde-reactions, for example, the formation of oL gozners hy polyaddition on the ionixed oarboxyl group of the car-huxyethylatiou product, and possibly decomposition of the lactone by the solvent. NeTOithdess, the carboxyethylatioti reaction is of interest as there ore no other practical methods "available for the preparation of some of tlie derivatives obtained ... 

Before going into the methods for radical reactions it most be said tlmt polycondensation or polyaddition have led to more industrial preparation. In this connection epoxy resins, the polyurethanes obtained from prepolymers and, more recently, more specialized polymers such as the PEB AC (ATOCHEM), amid-ether or polyimids (KHERIMIDE from RHONE POULENC must be mentioned). Moreover, it is interesting to note that the ionic methods (cationic or anionic ones) have not produced industrial products (except dihydroxy poly (dimethyl siloxanes), poly (tetrahydro-furanes)) but they have facilitated theoretical studies both on the analytical aspects and the materials we can obtain. 

The properties of polyaddition materials SIEL and STYK were analyzed by methods of longterm isothermal aging, DSK, TGA, and DTA (for example DTA and TGA curves of SIEL with methylphenylsiloxy units are presented) and radiography within a wide temperature range (Figs. 3-5). 

In fact, Bayer invented a new method for the synthesis of macromolecular compounds the polyaddition reaction, which is a special case of polycondensation, with the difference that the reaction product is exclusively the polymer. In the classical polycondensation reactions, the products are the polycondensation polymer and a low molecular weight (MW) compound (water, alcohols, and so on). The fact that in the polyaddition reactions... 

As with the inorganic fillers, the organic polymers can be successfully used as fillers. The preferred method is the synthesis of polymeric filler in situ, by radical polymerisation, polycondensation or polyaddition processes, developed in liquid polyether media [1-10]. 

The development of group transfer polymerization was followed shortly by the formation of macromonomers prepared by this technique. The method involves a nucleophilic polyaddition of trialkylsilyl vinyl ether monomers using an aldehyde as initiator in presence of a Lewis acid which acts as a catalyst [217]. The most common method for the preparation of macromonomers by this technique is the use of aldehydes having functional groups (functional initiation). 

In 1920 German scientist Hermann Staudinger published his theories on polyaddition polymerization, the formation of long-chain molecules. (Previously, the manner in which long-chain molecules were formed was unexplained.) Nine years later, in a publication that detailed the polymerization of styrene, this method of chain formation would be laid out. During this time period Staudinger developed polystyrene into a commercial product. A division of the German chemical company IG Earben, known as Badische Anilin- und Soda-Fabrik, or BASF, produced polystyrene in 1930. The Dow Chemical Company introduced the American public to polystyrene in 1937. 

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