Tailored hydrocarbon polymer

For the stabilization of various insoluble hydrocarbon polymers in carbon dioxide, it has been found that no one surfactant works well for all systems. Therefore it has become necessary to tailor the surfactants to the specific polymerization reaction. Through variation of not only the composition of the surfactants, but also their architectures, surfactants have been molecularly-engineered to be surface active—partitioning at the interface between the growing polymer particle and the CO2 continuous phase. The surfactants utilized to date include poly(FOA) homopolymer, poly(dimethylsiloxane) homopolymer with a polymerizable endgroup, poly(styrene-b-FOA), and poly(styrene-b-dimethylsiloxane). Through the utilization of these surfactants, the successful dispersion polymerization of methyl methacrylate (MMA), styrene, and 2,6-dimethylphenol in CO2 has been demonstrated. 

Dais membranes are reported to be much less expensive to produce than Nation they are also reported to exhibit a rich array of microphase-separated morphologies because of the ability to tailor the block length and composition of the unsulfonated starting polymer. The main drawback of employing hydrocarbon-based materials is their much... 

A hydrocarbon prepolymer containing terminal carboxyl groups (28) is available to the propellant chemist. These polymers were synthesized to eliminate some of the variables found in the copolymers. The carboxyl groups can be made of the same types with like reactivity. These linear non-branched polymers impart greater extensibility to elastomeric formulations. The chemistry in propellants is similar to the random functionality polymer. As 20 years of the chemistry of crosslinked propellant binders is reviewed, one familiar with the art cannot fail to predict solid propellant formulations using these polymers tailored to the specific requirements of the solid rocket design with the confidence that any discipline of science can be practiced. 

Examples of catalytic reactions and processes relevant to hydrocarbon chemistry are numerous. The technologies of the oil refinery with extremely low (<0.1) E factors are excellent examples demonstrating the possibilities that can be achieved by the development of selective catalytic methods, particularly by the use of various solid acids (see detailed discussions in Chapter 2). Further examples of commercially highly successful processes are the oxidation catalyst TS-1 developed by Enichem researchers160 161 (see Sections 9.1.1, 9.2.1, and 9.4.1), the homogeneous aqueous-phase Rh-catalyzed hydroformylation (see Sections 7.1.3 and 7.4.1), and single-site metallocene polymerization catalysts, which allow the preparation of tailored polymers with new properties (see Sections 13.3.2).162-164... 

Nowadays, a great number of different monomers are known that form conducting polymers upon chemical or electrochemical preparation techniques. Such starting systems include substituted derivatives of the already mentioned hydrocarbons and heterocycles as well as specially tailored novel compounds, such as for the generation of small band-gap polymers with high transparency in the conducting state (Fig. 1). 

This situation changed when a new breed of homogeneous catalysts, based on metallocenes and methylalumoxane (MAO) as co-catalyst, which are 10-100 times more active than common heterogeneous ones, found great industrial and scientific interest [15,16]. The metallocene and the MAO, as well as the active complex, are soluble in hydrocarbons. Using these catalysts it became possible to tailor the microstructures of the polymers by tuning the ligands. Table 1 reviews the efficiency of the zirconocene/methylalumoxane catalysts. 

PAOs are synthetic lubricant bases, sometimes referred to as synthetic hydrocarbons, produced by a chemical polymerisation process, typically of 1-decene, Chapter 2. The resulting polymer chain lengths can be tailored to provide the fluid with the physical characteristics required ... 

Plasticizers are most commonly liquid esters of low volatUity, which are blended into rigid thermoplastic polymers to make them soft and flexible. Most are esters of phthatic, phosphoric, and adipic acids. Major use is in polyvinyl chloride (PVC) elastoplastics. Another major use, rarely mentioned in the literature, is the addition of hydrocarbon oils to rubber to improve processability. Plasticizers are also used to improve melt processabUity and toughness of rigid plastics such as cellulose esters and ethers, and they are used in a variety of specialized apphcations. In some cases, they perform dual functions such as thermal stabilization or flame retardance. This gives the individual processor the ability to tailor properties for each produet. 

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