QandeValues for Free Radical Copolymerizations of Vinyl Monomers and Telogens

Greenley, Robert Z.

doi:10.1002/0471532053.bra008

Cited by 10 publications

(9 citation statements)

References 4 publications

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“…The reliability of the parameters is dependent not only on the theory used to obtain these relationships and the computational approach but also on the reliability of the experimental values of the Q − e parameters used in the calibration. The most popular experimental Q and e values in use are those listed by Greenley in the “Polymer Handbook” . Laurier et al have pointed out the deficiencies in the calculation and listing procedure used by Greenley and proposed an approach to determine Q and e values by using a statistically correct process.…”

Section: Resultsmentioning

confidence: 99%

A Density Functional Theory Approach to the Development of Q−e Parameters for the Prediction of Reactivity in Free-Radical Copolymerizations

Chen

Dixon

2002

J. Phys. Chem. A

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The Q − e scheme was developed for the interpretation of the reactivity of a monomer containing a double bond in free-radical copolymerizations. This empirical scheme has proven to be remarkably useful and continues to be the only general reactivity scheme in use today. To develop a reliable computational approach for the theoretical prediction of the Q and e values of molecules whose experimental Q and e values have not been established, we have analyzed the Q−e approach to develop a computational approach to their prediction. We then performed density-functional theory (DFT) calculations on molecules whose experimental Q and e values are available to develop a set of correlation parameters for monomers without experimental values. It has been demonstrated that for a general choice of the Q and e values of the reference monomer that both parameters Q and e should be dependent on the energetic properties of the free-radical reaction and the polar properties of the monomer and radical. To correlate the Q and e parameters with these properties, the overall quality of the calibrated correlation relationships should not be affected by the choice of the reference Q and e values. Satisfactory relationships have been found for the correlations of the Q−e parameters with DFT-calculated electronegativities and reaction free energies, suggesting that the electronegativity and reaction free energy determined by the DFT calculations reasonably reflect the polar and energetic properties, respectively, needed for Q−e parameter development. With the particular choice of the popularly used reference values of Q = 1.0 and e = −0.8 for styrene, the parameter e is dependent only on the calculated electronegativity, and the parameter Q is dominated by the calculated reaction free energy of the process of adding a radical to a CC double bond. The explicit relationships obtained in this work can be used to predict unknown Q and e parameters based on DFT calculations.

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Section: Resultsmentioning

confidence: 99%

A Density Functional Theory Approach to the Development of Q−e Parameters for the Prediction of Reactivity in Free-Radical Copolymerizations

Chen

Dixon

2002

J. Phys. Chem. A

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“…Much more confused is the case of the calculation of Q − e values, which was already discussed by many authors. − Taking into consideration the copolymerization parameters with some reference monomers (styrene, ethylene, TFE, and VDF), the Q and e values of which are reported in the literature, ,,,,,,,− the Q − e values of FAc were calculated from the Alfrey−Price scheme, compared with those of other VDF−comonomer systems (Table ). But we have to claim that they were determined from a set of experiments for a single copolymer system, taking into account the values of similar monomers.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Polymerization of Fluorinated Monomers Bearing a Reactive Lateral Group. 9. Bulk Copolymerization of Vinylidene Fluoride with 4,5,5-Trifluoro-4-ene Pentyl Acetate

et al. 1999

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Bulk copolymerization of vinylidene fluoride (or 1,1-difluoroethylene (VDF)) with 4,5,5-trifluoro-4-ene pentyl acetate (FAc) initiated by di-tert-butyl peroxide is presented. A series of nine copolymerization reactions was investigated from initial [VDF] 0/[FAc]0 molar ratios ranging from 32/68 to 95/5. Both these comonomers copolymerized in this range of copolymerization. Moreover, these comonomers homopolymerized separately in these conditions. The copolymer compositions of these randomtype copolymers were calculated by means of 1 H and 19 F NMR spectroscopies and allowed one to quantify the respective amount of each monomeric unit in the copolymer. From the Tidwell and Mortimer method, the reactivity ratios, ri, of both comonomers were determined showing a higher incorporation of FAc in the copolymer (rFAc ) 3.26 ( 1.49 and rVDF ) 0.17 ( 0.10 at 120°C). Alfrey-Price's Q and e values of trifluorovinyl acetoxy monomer FAc were calculated to be 0.060 (from QVDF ) 0.008) or 0.040 (from QVDF ) 0.015) and +1.14 (vs eVDF ) 0.40) or +1.23 (vs eVDF ) 0.50), respectively, indicating that FAc is an electron-accepting monomer. The normalized monomer-diad and -triad fractions as a function of the polymer composition were obtained from the comonomer sequence distribution theory and this was evidenced by 19 F NMR analysis.

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“…The tendency to alternation in these copolymers can be explained by the Q and e values of both comonomers. The literature reports that these pairs are (0.008, 0.40), (0.015, 0.50), and (0.036, 1.20) 68 for VDF while for MTFA they are (0.035, 2.37), (0.048, 1.20), , (0.15, 1.7), and (0.05, 2.4) . Besides, according to the Alfrey and Price 71 equation and considering average values of Q MTFA = 0.04, e MTFA = 1.8, Q VDF = 0.015, and e VDF = 0.5, such values should lead to r VDF = 0.7, while r MTFA = 0, which are rather close to the experimental values.…”

Section: Resultsmentioning

confidence: 95%

“…However, a recent program for the assessment of the reactivity ratio values, using a nonlinear method, could be useful and deserves deeper investigation. Taking into account compilation of Q and e values for fluoromonomers, , the general tendency is such that the higher the number of fluorine atoms on the double bond, the greater the e value. In most cases, Q values are very small except for those of styrenic and acrylic monomers.…”

Section: Resultsmentioning

confidence: 99%

Unexpected Alternating Copolymerization of Vinylidene Fluoride Incorporating Methyl Trifluoroacrylate

et al. 2003

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The radical copolymerization of methyl trifluoroacrylate (MTFA) with vinylidene fluoride (or 1,1-difluoroethylene, VDF), initiated by tert-butyl 2,2-dimethylperoxypropanoate, is presented. The kinetics of copolymerization was investigated in a series of eight reactions for which the initial [VDF] 0/ [MTFA]0 molar ratios ranged between 14.5/85.5 and 88.7/11.3. The composition of copolymers, i.e., the molar ratios of VDF and MTFA monomeric units in the copolymers, was determined by 19 F NMR spectroscopy mainly. The reactivity ratios, ri, determined according to the Tidwell and Mortimer law, were assessed to be: rVDF ) 0.30 ( 0.03 and rMTFA ) 0 at 50 °C, which clearly shows tendency of the copolymerization system toward alternation copolymerization. Copolymerizations at high monomer conversions were also attempted and showed a good incorporation of MTFA and rather high molecular weights (up to 26000).

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QandeValues for Free Radical Copolymerizations of Vinyl Monomers and Telogens

Cited by 10 publications

References 4 publications

A Density Functional Theory Approach to the Development of Q−e Parameters for the Prediction of Reactivity in Free-Radical Copolymerizations

A Density Functional Theory Approach to the Development of Q−e Parameters for the Prediction of Reactivity in Free-Radical Copolymerizations

Synthesis and Polymerization of Fluorinated Monomers Bearing a Reactive Lateral Group. 9. Bulk Copolymerization of Vinylidene Fluoride with 4,5,5-Trifluoro-4-ene Pentyl Acetate

Unexpected Alternating Copolymerization of Vinylidene Fluoride Incorporating Methyl Trifluoroacrylate

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