Proton NMR of polybutadiene at 300 MHz: cis‐1,4‐trans‐1,4 linkages

Santee, E. R.; Mochel, V. D.; Morton, Maurice

doi:10.1002/pol.1973.130110705

Cited by 42 publications

(22 citation statements)

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“…Geminal and vicinal interactions with SSC constants achieving 16 Hz in modulus complicate the spectra, whereas allyl and homoallyl SSCs (1-2 Hz) broaden lines. To reduce undesirable consequences of SSCs in the 1 H NMR spectroscopy of diene polymers, the selective deuterosubstitution of protons of certain groups of the sample [28,30,33] and spin decoupling [22,[25][26][27] were used. However, the employment of these techniques is unpractical.…”

Section: Resultsmentioning

confidence: 99%

Determination of configurational isomers in polybutadienes by 1H and 13C NMR spectroscopy

Makhiyanov

2012

Polym. Sci. Ser. A

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In the polymerization of 1,3 butadiene, chain growth occurs via addition of the monomer at 1,2 or 1,4 positions; in the latter case, cis 1,4 and trans 1,4 configurations can form.It is well known [1,2] that the configurational-iso metric composition (c, t, v) along with other micro structure parameters (monomer unit distributions in a chain, average length of monomer block sequences, specific content of possible combinations of units, etc.) exert the decisive effect on the properties of PB. The relationship between the parameters (c, t, v) and properties of PB is still at the focus of researchers' attention [3][4][5][6][7]. In this case, the question arises as to whether the determination of the above parameters is correct [6].The structure of PB is investigated with the use of such nondestructive methods as vibrational spectros copy (IR and Raman) [8][9][10][11][12][13][14][15] and high resolution NMR . In research and industrial laborato ries, IR spectroscopy is the most popular method owing to its accessibility and simplicity. However, for quantitative measurements, this method requires cali bration [13] and is inferior to NMR spectroscopy in informative value. Over the past half century, the structure of PB has been intensively studied with the use of NMR spectroscopy: high resolution 1 H [16-36] and 13 C [33, 37-73] NMR spectroscopy of liquid (dissolved) samples, solid state 13 C NMR spectros copy [74][75][76], and two dimensional spectroscopy [73,[77][78][79]. Despite the considerable progress of mag netic resonance techniques, solid state and multidi mensional variants are still inferior to "classical" (i.e., liquid one dimensional) NMR for solving quantita tive problems. Therefore, our study concerns only the potential of the latter method for estimating the values of c, t, and v for polybutadiene.The use of NMR spectroscopy for the quantitative analysis of the structure of PB was discussed in [11,17,30,51,59,60]. However, this problem is still topical. First, the requirements imposed on the informative level and accuracy of the NMR method [80-82], including those for the study of polymers [83], are increasing steadily. Second, a widespread opinion about the completeness of assignment and easy analy sis of the spectra of PB as the simplest diene polymer is contrary to reality [6, 71-73, 79, 84].The goal of this study is to solve a complex of meth odological problems arising during determination of the isomeric composition of PB with the use of NMR spectroscopy. EXPERIMENTALCommercial PBs (DOW SE BR 1202D, BUNA CB 530T, DOW SE PB 5800, SKDN and SKD L rubbers manufactured by OAO Nizhnekam skneftekhim, and SKB and SKD 2 manufactured by the Kazan and Efremov synthetic rubber plants, respectively) and laboratory samples PB 11, PB 15, PB 35, PB 38, PB 55, and PB 67 were used in this study. Laboratory samples were synthesized with the use of a lithium containing initiation system, as described in [84]. The PB samples were dissolved in chloroform d and benzene d 6 (the solution concen tration was 1 wt %) when th...

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Section: Resultsmentioning

confidence: 99%

Determination of configurational isomers in polybutadienes by 1H and 13C NMR spectroscopy

Makhiyanov

2012

Polym. Sci. Ser. A

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“…Polybutadienes prepared using alkyl lithium initiators in hydrocarbon solvents have also been shown to have random distributions of 1,4-cis and 1,4-trans units [20,23,71,90].…”

Section: 4-cis/l4-trans Polydienesmentioning

confidence: 97%

“…Such polymers can be considered to be stereoregular copolymers, and their nmr spectra can be analyzed to obtain information about the relative amounts of cis and trans units present and their arrangement along the polymer chain. The structures of polymers derived from cyclopentene [87][88][89], cyclooctadiene [71,90] and bicyclo-2,2-1-octene [89,91] have been studied by nmr spectroscopy, for example. The relative amounts of cis and trans units present vary with reaction conditions, but the cis and trans units are generally distributed randomly along the polymer chains.…”

Section: Polymers From Cyclic Olefinsmentioning

confidence: 99%

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NMR Analysis of Stereo Regular Copolymers

Harwood

1979

Preparation and Properties of Stereoregular Polymers

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Stereoregular copolymers are formed by the chemical modification of stereoregular polymers, by copolymerizations of ~-olefins in the presence of stereoregulating catalysts and by ring opening copolymerizations of chiral monomers. Also appropriate for consideration are polydienes containing cis-l,4-and trans-l,4-units as well as those containing 1,2-{or 3,4-) and 1,4-units. Analysis of such copolymers by NMR spectroscopy provides information about their compositions and the arrangement of monomer units along their chains. Such information is valuable for understanding the chemical behavior of stereoregular polymers and the mechanisms of stereoregular polymerization processes. STRUCTURAL FEATURES PRESENT IN STEREOREGULAR COPOLYMERSIf a stereoregular copolymer containing A and B monomer units is considered, then some of its structural features that can be measured by NMR spectroscopy can be listed as follows.

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“…It will vary with the particular system being studied and the relationship of the measurement temperature to its T g • Moreover, linewidths vary considerably with the amount of filler present,88.97 and presumably also with cross-link density. Thus, linewidths vary from a few hertz for unfilled simple systems such as polybutadiene or polyisoprene to 70 Hz or more for a heavily black filled vulcanised rubber. 88 ,98 In general, if the material is soluble, then superior detail will be seen in solution, but we have found that useful information on the identification and gross stereochemical features of most cross-linked rubbers, even when they contain appreciable amounts of filler, can be obtained.…”

Section: C Nmr Of Solidsmentioning

confidence: 98%