Transformation reactions polymerization

Hydroboration of a,C0-dienes with monoalkylboranes gives reactive organoboron polymers which can be transformed into polymeric alcohols or polyketones by carbonylation, cyanidation, or the DOME reaction followed by oxidation (446—448). 

The synthetic methods of macromolecules having an active pendant group include (1) the transformation reactions of polymer and copolymers, and (2) polymerization and copolymerization of functional monomers having active pendant groups. The macromolecules, either in the shape of film or microbeads, can be used as the substrate. As we have mentioned previously, the rate of polymerization initiated with the Ce(IV) ion redox system is much faster than that initiated by Ce(l V) ion alone, as expressed in / r 1. Therefore, the graft... 

These techniques help in providing the following information specific heat, enthalpy changes, heat of transformation, crystallinity, melting behavior, evaporation, sublimation, glass transition, thermal decomposition, depolymerization, thermal stability, content analysis, chemical reactions/polymerization linear expansion, coefficient, and Young s modulus, etc. 

Many block and graft copolymer syntheses involving transformation reactions have been described. These involve preparation of polymeric species by a mechanism that leaves a terminal functionality that allows polymerization to be continued by another mechanism. Such processes are discussed in Section 7.6.2 for cases where one of the steps involves conventional radical polymerization. In this section, we consider cases where at least one of the steps involves living radical polymerization. Numerous examples of converting a preformed end-functional polymer to a macroinitiator for NMP or ATRP or a macro-RAFT agent have been reported.554 The overall process, when it involves RAFT polymerization, is shown in Scheme 9.60. 

Polymer properties, influence of ions, 258 Polymer surface reactions, kinetics, 322-323 Polymer transformation reactions configurational effect, 38 conformational effects, 38 hydrolysis of polyfmethyl methacrylate), 38 neighboring groups, 37-38 quaternization of poly(4-vinyl pyridine), 37-38 Polymerization, siloxanes, 239... 

The preparation of a functional segmented block copolymer was also investigated (scheme ll).15 First hydroboration polymerization of the oligomer using thexylborane was carried out. Then the obtained organoboron polymer was subjected to a chain-transformation reaction (DCME rearrangement). DCME and lithium alkoxide of 3-ethyl-3-pentanol in hexane was added to a THF solution of the polymer at 0°C. 

The transformation of the chain end active center from one type to another is usually achieved through the successful and efficient end-functionalization reaction of the polymer chain. This end-functionalized polymer can be considered as a macroinitiator capable of initiating the polymerization of another monomer by a different synthetic method. Using a semitelechelic macroinitiator an AB block copolymer is obtained, while with a telechelic macroinitiator an ABA triblock copolymer is provided. The key step of this methodology relies on the success of the transformation reaction. The functionalization process must be 100% efficient, since the presence of unfunctionalized chains leads to a mixture of the desired block copolymer and the unfunctionalized homopolymer. In such a case, control over the molecular characteristics cannot be obtained and an additional purification step is needed. 

Billions of pounds of polyolefins are produced annually in the world [1], Through simple insertion reactions, inexpensive and abundant olefins are transformed into polymeric materials for a wide range of applications including plastics, fibers, and elastomers. Despite its long history, the polyolefin industry continues to grow steadily and remains technologically driven because of continuous discovery of... 

The catalytic transformation of olefins by transition metal complexes has received a great deal of attention during the past two decades. These catalytic reactions are important, especially industrially, because they represent some of the most economical ways to synthesize olefinic monomers or polymers. The more common types of these transformation reactions are (a) dimerization or polymerization of a-olefins (b) dimerization, oligomerization, cyclooligomerization, or polymerization of con-... 

Abiotic organic reactions, such as hydrolysis, elimination, substitution, redox, and polymerization reactions, can be influenced by surfaces of clay and primary minerals, and of metal oxides. This influence is due to adsorption of the reactants to surface Lewis and Br nsted sites. Temperature and moisture content are the most important environmental variables. Under ambient environmental temperatures, some reactions are extremely slow. However, even extremely slow transformation reactions may be important from environmental and geochemical viewpoints. 

Another approach to block copolymers involves changing the type of propagating center part way through the synthesis via a transformation reaction [Burgess et al., 1977 Richards, 1980 Souel et al., 1977 Tung et al., 1985]. For example, after completion of the living anionic polymerization of monomer A, the carbanion centers are transformed into carbocations... 

Most of the methods for synthesizing block copolymers were described previously. Block copolymers are obtained by step copolymerization of polymers with functional end groups capable of reacting with each other (Sec. 2-13c-2). Sequential polymerization methods by living radical, anionic, cationic, and group transfer propagation were described in Secs. 3-15b-4, 5-4a, and 7-12e. The use of telechelic polymers, coupling and transformations reactions were described in Secs. 5-4b, 5-4c, and 5-4d. A few methods not previously described are considered here. 

The synthesis of poly(MMA-fr-IB-fr-MMA) triblock copolymers has also been reported using the site-transformation method, where a,site-transformation technique provides a useful alternative for the synthesis of block copolymers consisting of two monomers that are polymerized only by two different mechanisms. In this method, the propagating active center is transformed to a different kind of active center and a second monomer is subsequently polymerized by a mechanism different from the preceding one. The key process in this method is the precocious control of a or co-end functionality, capable of initiating the second monomer. Recently a novel site-transformation reaction, the quantitative metalation of DPE-capped PIB carrying methoxy or olefin functional groups, has been reported [90]. This method has been successfully employed in the synthesis of poly(IB-fr-fBMA) diblock and poly (MMA-fc-IB-fo-MMA) triblock copolymers [91]. 

Supercritical carbon dioxide (SCCO2) has been shown to be a promising alternative solvent medium for organic transformations and polymerization reactions. This stems from a list of advantages ranging from solvent properties to practical, environmental, and economic considerations. Moreover, no residual solvent remains in the polymer product. Additionally carbon dioxide is inexpensive, readily available and nonflammable. 

Fig. 15. Optical addition polymerization of the AC series b to g upon 364 nm irradiation of the TS-6 crystal. The initial spectrum at 0 min corresponds to the final spectrum of Fig. 6. In addition transformation reactions to the y, 8-series are observed...

The synthesis of boron-capped clathrochelate iron(II) tris-dioximates has been realized for wide range of substituents at the boron atom. The attempts to obtain analogous trialkyl- and triaryl-tin-capped iron(II) compounds have not been successful. In the some cases, polymeric clathrochelate compounds have been formed, especially when reactions proceed under basic conditions. With tin(IV) iodide, the primarily formed soluble green complexes also readily transform into polymeric red compounds that are presumably associated with the detachment of iodide ions because of steric hindrance between substituents in dioxime fragments and the bulky iodide atoms of capping groups [70],... 

The second route (87, 98) to block copolymers is the anion to Zie-gler-Natta transformation reaction. Living anionic polymerizations (polymerizations that do not terminate) of styrene and isoprene are treated with... 

The Durham route to polyacetylene 103, 104) involves the metathesis polymerization of 1 to give a soluble but thermally unstable high polymer (Scheme 5.2). Slowly at room temperature, or more rapidly at 80 °C, the polymer undergoes a retro-Diels-Alder reaction. This reaction results in elimination of a substituted benzene and formation of amorphous polyacetylene. An enormous weight loss accompanies the conversion, but high-density films were produced with no apparent voids. The kinetics of the transformation reaction were extensively studied (JOS). 

From a view point of reaction time, the typical preparation of mesoporous material can be divided three main steps (1) interaction between surfactant and silica (or other inorganic) species in solution and the formation of ordered mesostmcture (2) the further reaction (polymerization or condensation for silica) at a certain temperature for a time period. A possible phase transformation may occur (3) recovery of solid product by filtration, washing, and drying. The phase transformation may also occur in this step (4) removal of template from the solid product by calcination or extraction with solvent. The phase transformation is also possible even in this step. 

Nonequilibrium behavior during solute transport in soil may also result from time-dependent chemical and biological transformation reactions. Consideration of chemical fixation, dissolution, hydrolysis, and polymerization reactions in mathematical models are often necessary to correctly describe the transport of certain solutes in soil. Time-dependent biological reactions that transform solutes into a variety of chemical species may also need consideration during solute transport in some soils. 

The following transformation reactions Involving the ring opening polymerization of THF have been examined. 

There have been numerous examples of transformation reactions that combine either preformed macroinitiators or different polymerization techniques with the CRP of various monomers reported in the literature. 

Siloxanes are another class of cyclic monomers that have been incorporated into CRP copolymers via a transformation reaction. Miller and Matyjaszewski used n-butyllithium to initiate the ROP of hexamethylcyclotrisiloxane (D3), then terminated the polymerization with chlorodimethylsilane [234]. Allyl 2-bromoi-sobutyrate was then incorporated via a hydrosilylation reaction using Karstedt s catalyst. This reaction did not achieve a high end-functionality, but use of 3-butenyl 2-bromoisobutyrate, and the addition of 0.2 mol% of 2-methyl-l,4-... 

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