Side vinyl group

Concentrations are expressed in moles of olefin groups per liter and absorptivities in liters per mole-cm. The concentration of the side vinyl group in the sodium polymer is cvi and for the trans-vinylene group, 15.3 — Cvi similarly for the emulsion polymer, cv> is vinyl, and 15.8 — cv2 is trans concentration. Solving these equations gave molar absorptivities and concentrations from which calibration curves were constructed, relating corrected absorbance at 910 and 967 cm."1 to concentration of side vinyl and trans groups, respectively. 

Composition and microstructure determination of polybutadiene (BR) and natural rubber (NR) can be done by infrared spectra. Three different base units are possible for linear addition polymers of 1,3 butadiene units with cis or trans internal double bands from 1,4 addition and units with side vinyl groups from 1,2 addition (see Scheme 3.1a). 

Homqpolymerization of these MOl is rather conplicated but they can be cqpolymerized with MMA, styrene and other traditional monomers. This is also true of metalloporphyrin monomers with one or two side vinyl groups (43, 44). 

The data in Table XV illustrate the problems encountered in such copolymerizations, since the use of polar solvents to assure a random styrene-diene copolymer of desired composition will, at the same time, lead to an increase in side vinyl groups (1,2 or 3,4) in the diene units (see Table XIV). This is of course quite undesirable, since such chain structures result in an increase in the glass transition temperature (Tg) and therefore to a loss of good rubbery properties. Hence, two methods are actually used to circumvent this problem (1) the use of limited amounts of polar additives such as tetrahydrofuran to... 

Copolymer of olefins with carbon oxide and an unsaturated grignard compound followed by hydrolysis allows one to obtain a co-oUgomer with side vinyl groups wherein the chain is made up of structures of the type —CH2—CH(R)—... 

Dienes with isolated double bonds can polymerize with the formation of cross-linked polymers, because the two double bonds present in the molecule can react independently of each other. However, in some cases in addition reactions both double bonds of monomer molecules can take part, leading to the formation of cyclic polymers. This reaction occurs particularly when it leads to the formation of rings with five or six-members. During the cyclization reaction side vinyl groups are formed, which pol3mierize with formation of cyclic polymers. 

Dienes with tt electron conjugated double bonds, such as 1,3- butadiene and its derivatives undergo an addition process in both positions 1.2 and 1.4. As a result of the polymerization process of 1.2 type a polymer containing side vinyl groups is formed, while 1.4 addition reaction leads to a polymer with double bond in the chain. In that case both configurations cis and trans are equally possible. 

Another approach to the fabrication of LB films from prefonned polymers is to fonn a hydrophobic main chain by reacting monomers tenninated by a vinyl group [102, 103, 104, 105 and 106]. The side groups studied also included perfluorinated hydrocarbon chains, which tilt with respect to the nonnal to the plane of the film, whereas the analogous ordinary hydrocarbon chains do not [105]. 

Hydrogenation of polybutadiene converts both cis and trans isomers to the same linear structure and vinyl groups to ethyl branches. A polybutadiene sample of molecular weight 168,000 was found by infrared spectroscopy to contain double bonds consisting of 47.2% cis, 44.9% trans, and 7.9% vinyl. After hydrogenation, what is the average number of backbone carbon atoms between ethyl side chains ... 

Polyester composition can be determined by hydrolytic depolymerization followed by gas chromatography (28) to analyze for monomers, comonomers, oligomers, and other components including side-reaction products (ie, DEG, vinyl groups, aldehydes), plasticizers, and finishes. Mass spectroscopy and infrared spectroscopy can provide valuable composition information, including end group analysis (47,101,102). X-ray fluorescence is commonly used to determine metals content of polymers, from sources including catalysts, delusterants, or tracer materials added for fiber identification purposes (28,102,103). 

Conformation. The exact conformation of the isoprene molecule is stiU in doubt. It is generally accepted that rotation is restricted around the central C—C single bond. Isoprene may be considered as an equiHbrium of two conformations, namely a cisoid s-cis) conformation in which both vinyl groups are located on the same side of the C—C bond, and a transoid s-trans) one with the vinyl groups located on the opposite sides of the bond. The predominance of the trans-planar or nonplanar configuration has been supported by experimental data (10—14). 

The simplest linear-chain polymer is polyethylene (Fig. 22.3a). By replacing one H atom of the monomer by a side-group or radical R (sausages on Fig. 22.3b, c, d) we obtain the vinyl group of polymers R = Cl gives polyvinyl chloride R = CIT3 gives... 

The additional coupling (9.8 Hz) of the cyclopropane proton A at <5// = 1.60 is the result of a vicinal H atom in the side-chain. This contains a methyl group B, a vinyl group C and an additional substituted ethenyl group D, as may be seen from the one dimensional H and C NMR spectra and from the CH COSY diagram. 

Introduction of some vinyl groups in a side chain enables vulcanisation to take place. It is claimed that when stabilised with ferric oxide the materials may be used operationally to 250°C and the possibility of short-term use up to 400°C has... 

The relative orientation of the substituent and the side-chain— in terms of the benzene ortho, meta, para scheme—is an added complication. Following the practice first established by Hammett in treating the furoic acids, it is customary to treat the heteroatom QNH, S, O) as if it had replaced a vinyl group (—CH=CH—) in benzene. Thus, the 4-R-2-Y and 5-R-3-Y relationships become meta, and 5-R-2-Y becomes para. 

As this takes place, the inhibitor molecule is regenerated, and side methyl group is substituted by end vinyl [41]. 

To form the desired vinyl group, the methoxyethyl-substituted porphycene 9, has to be converted into its nickel complex. In the nickel porphycene the methoxyethyl side chain is... 

When the compound to be alkylated is a nonsymmetrical ketone, the question arises as to which side will be alkylated. If an a phenyl or a vinylic group is present on one side, alkylation goes predominantly on that side. When only alkyl groups are present, the reaction is generally not regioselective mixtures are obtained in which sometimes the more alkylated and sometimes the less alkylated side is predomi-... 

A series of theoretical studies of the SCV(C)P have been reported [38,40,70-74], which give valuable information on the kinetics, the molecular weights, the MWD, and the DB of the polymers obtained. Table 2 summarizes the calculated MWD and DB of hyperbranched polymers obtained by SCVP and SCVCP under various conditions. All calculations were conducted, assuming an ideal case, no cyclization (i.e., intramolecular reaction of the vinyl group with an active center), no excluded volume effects (i.e., rate constants are independent of the location of the active center or vinyl group in the macromolecule), and no side reactions (e.g., transfer or termination). 

Ando and co-workers have reported the synthesis of a silyl-carborane hybrid diethynylbenzene-silylene polymer (108) (Fig. 66) possessing high thermal stability.136 The polymer contained Si and —C=C— group in the main chain and m-carborane and vinyl groups in the side chain. The 5% weight-loss temperature of the cured polymer in air was over 1000°C as determined by thermogravimetric analysis. 

The addition of a large excess of bis(cj-alkenyl)zinc compounds to the TiC -catalyzed polymerization of propene resulted in an increased polymer yield, but a reduction in the molecular weights of the polymers.64 This suggests that the diorganozinc compounds are both co-catalysts and chain-transfer agents in this polymerization. The catalyst activity decreased in the order bis(3-butenyl)zinc < bis(7-octenyl)zinc < chlorodiethylaluminum. Bis(7-octenyl)zinc was co-polymerized with propene to afford hexylzinc side chains, whose zinc-carbon moieties were converted to vinyl groups by the addition of allyl bromide. 

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