Molar mass conversions with

Fig. 7-3 Additional Conversions. Moles of a gas may be determined from other data, such as moles of another reagent in a chemical reaction or mass and molar mass. Conversely, these values may be determined from gas data by working in the opposite direction on the figure. Again, start with the data provided and work toward the answer required. (Remember the boy scouts.)... 

Already before reporting this combined inifer and living polymerization approach, Kennedy and coworkers developed a controlled isobutene polymerization method based on cumyl ester initiators (Scheme 8.6) with boron trichloride as activator and incremental monomer addition [28], The livingness of the polymerization was demonstrated by the linear increase of number-average molar mass and the constant number of polymer chains (A) with the amount of PIB obtained (wp, as measure for conversion) as well as the narrowing of the molar mass distribution with conversion (Fig. 8.1) [28]. 

Polymers with metals in the side groups can be produced by polymerization of the corresponding monomers or by polymer analog conversion. For example, vinyl ferrocene copolymerizes to high-molar-mass products with, for example, styrene under the influence of nonoxidizing free radical initiators such as AIBN. BPO oxidizes the iron. 

To obtain a high molar mass product, the mixture must be stoichiometric on the other hand, controlled deviations from stoichiometry can be used to lower the molar mass. In contrast with chain polymerization, where high molar mass molecules are formed right from the start, molar mass increases with the degree of conversion and large molecules are only formed at very high conversion. A consequence of this is that step polymers tend to have lower masses and narrower mass distributions than chain polymers. 

Mechanistic studies on the formation of PPS from polymerization of copper(I) 4-bromobenzenethiolate in quinoline under inert atmosphere at 200°C have been pubUshed (91). PPS synthesized by this synthetic procedure is characterized by high molar mass at low conversions and esr signals consistent with a single-electron-transfer mechanism, the Sj l-type mechanism described earlier (22). 

This dicarboxy-terminated oligomer is prepared by reacting excess adipic acid with 1,2-edianediol in die bulk until hydroxyl group conversion is complete (Scheme 2.47). The molar mass of final polymer depends on the initial molar ratio of monomers (procedure similar to that described in ref. 401). 

An enzyme obtained from human plasma by conversion of profibrinolysin with streptokinase to fibrinolysin. Proteolytic enzyme of unknown structure molar mass = 75000. 

In all calculations the molar masses given in the top of Table I were used. First of all, the effects of variations in the concentration of trifunctional monomers were determined, as exemplified by the nine formulations of Table I and the resulting prepolymer characteristics after full conversion given in Table II. Formulations FIO to F40 result in branched prepolymers, which are cured in the third stage by difunctional monomers. On the other hand, formulations FOO to F04 result in the same linear prepolymer, which is subsequently cured with various mixtures of di- and trifunctional monomers. The number average functionalities of PI (and P2) and of the mixtures of E and F monomers are varied systematically between 2.0 and 2.4. Therefore, the only difference between formulations FjO and FOj is the stage in which the branching units are added. 

Figures 2 and 5 show the increase of the mass average molar mass, R i, with conversion for the systems with branched and linear prepolymers, respectively. These results indicate that addition of the branching monomer in the first stage yields much higher values of R, and the gel point is reached at lower conversion than addition in the third stage. Translated into practical properties this means that the processing and application qualities (e.g. flow) of a paint based on formulation F40 will be inferior to those of one on the basis of for-...

As with all calculations of chemical amounts, we must work with moles. Because grams are asked for, we must do a mole-mass conversion this requires the molar mass of the substance, which in turn requires that we know the chemical formula. 

In 1994, we reported the dispersion polymerization of MM A in supercritical C02 [103]. This work represents the first successful dispersion polymerization of a lipophilic monomer in a supercritical fluid continuous phase. In these experiments, we took advantage of the amphiphilic nature of the homopolymer PFOA to effect the polymerization of MMA to high conversions (>90%) and high degrees of polymerization (> 3000) in supercritical C02. These polymerizations were conducted in C02 at 65 °C and 207 bar, and AIBN or a fluorinated derivative of AIBN were employed as the initiators. The results from the AIBN initiated polymerizations are shown in Table 3. The spherical polymer particles which resulted from these dispersion polymerizations were isolated by simply venting the C02 from the reaction mixture. Scanning electron microscopy showed that the product consisted of spheres in the pm size range with a narrow particle size distribution (see Fig. 7). In contrast, reactions which were performed in the absence of PFOA resulted in relatively low conversion and molar masses. Moreover, the polymer which resulted from these precipitation... 

It is well-known that the coil density of macromolecules decreases with increasing molar mass. Due to cyclization this decrease in density becomes less or even disappears because the macromolecules of higher molar mass are more strongly contracted than those of lower molar mass. After a certain conversion of pendant vinyl groups, the influence of the intermolecular reaction on [r ]... 

Fig. 40. A Relation between [-r ] and Mw during crosslinking of PVS. B Increase of Mw with the conversion of pendant vinyl groups during crosslinking of PVS. Molar mass of starting PVS, Mw0 = 135000 g/mol. Temperature = 70 °C. The PVS concentrations are shown in the figures [217].

Copper bromide and pentakis-A-(heptadecafluoroundecyl)-l,4,7-triazeheptane (1 in Figure 10.9), along with an initiator, ethyl-2-bromoisobutyrate (2 in Figure 10.9), in a perfluoromethylcyclohexane-toluene biphase efficiently catalyse the polymerization of methyl methacrylate, with a conversion of 76 % in 5 h at 90 °C. The resultant polymer has a Mn = 11100 and a molar mass distribution of 1.30. After polymerization, the reaction was cooled to ambient temperature, the organic layer removed and found to contain a copper level of 0.088 % (as opposed to 1.5% if all the catalyst were to have remained in the polymer). A further toluene solution of monomer and 2 could be added,... 

The product was identified by comparison of its retention time and mass spectrum with those of a commercial standard substance. Under the given conditions, the final molar conversion yield was 37.5 %. 

At Coventry we have electropolymerised styrene in the presence and absence of ultrasound (38 kHz) at 0°C and at two different currents (100 mA and 400 mA). We used bright platinum electrodes, dichloromethane as solvent and tetrabutyl ammonium boron hexafluoride (TBABF5) as the electrolyte. At 400 mA we obtained complete conversion in 150 min vhth a resultant molar mass of 100000 compared with 70% conversion and a molar mass of 314000 in the absence of ultrasound. 

The ruthenium-triphenylphosphine system was also tested under very mild conditions [66]. At room temperature, quantitative monomer conversion was achieved within only 24 h. At 40 °C, polymers with well-controlled molar masses... 

The mechanism and kinetics of RAFT-SIP were studied by Fukuda et al. [326]. Besides the expected linear increase of the molecular weight of the surface grafted polymer with the monomer conversion, they observed the appearance of a prominent low molar mass fraction which was attributed to a combination reaction of the propagating active chains. 

Fig. 5 Semilogarithmic kinetic plot of Amor top left), molar mass and PDl value vs conversion plots for Amor (top right), iV,iV-dimethyl acrylamide (DMA) (bottom left), and 2-hydoxypropyl acrylate (HPA) (bottom right). (Reprinted with permission from [50]. Copyright (2008) American Chemical Society)...

Fig. 8 Semilogarithmic kinetic plot of the anionic polymerization of St (left) and molar mass and PDI values vs conversion plot (right). (Reprinted with permission from [55]. Copyright (2005) John WUey Sons, Inc.)...

Fig. 15 Number average molar masses (Mn opc) and PDI values obtained for the first blocks and for the final copolymers of PMA, PnBA, PMMA, or PDMAEMA (25 units) with PEEA (25, 50, 75, and 100 units for 100% conversion). AH Mn pc values are calculated against PMMA standards. SEC eluent CHClsiNEtsii-PrOH. (Reprinted with permission from [87]. Copyright (2005) American Chemical Society)...

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