Analysis of the sequence distribution of 1,2 units in polybutadiene by an ozonolysis-GPC method

Tanaka, Yasuyuki; Kawahara, Seiichi; Ikeda, Tomoyuki; Tamai, Hironori

doi:10.1021/ma00071a042

Cited by 9 publications

(9 citation statements)

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“…The diad sequence distribution and isomeric unit (microstructure) contents, estimated from the intensity ratios, are tabulated in Table III, together with the content of 1,2 unit determined by 1 H NMR spectroscopy. The diad sequence distribution of trans-1,4, cis-1,4, and 1,2 units for PB, prepared by anionic polymerization using n-butyllithium, was random, as reported in our previous work, 28,29 The content of 1,2 unit for PB determined by 13 C NMR measurement was similar to that determined by 1 H NMR measurement. Consequently, the PB used in the present study was confirmed to have the same 1,2 unit content as one used in our previous work.…”

Section: Characterization Of Nr-sol Nr-gel and Pbsupporting

confidence: 83%

Lower Critical Solution Temperature Phase Behavior of Natural Rubber/Polybutadiene Blend

Kawahara

Asada

Isono

et al. 2002

Polym J

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ABSTRACT:The lower critical solution temperature (LCST) phase behavior of the blend of natural rubber (NR) with polybutadiene (PB) having 32.3% 1,2 unit was investigated by measuring T g through DSC after annealing the blend. NR was separated with toluene into branched polymer and crosslinked one as a soluble fraction (NR-sol) and gel fraction (NR-gel), respectively, followed by mixing with PB. Coexistence composition of NR-sol/PB and NR-gel/PB blends was determined by a method proposed in this work using DSC. The LCST of the NR-sol/PB blend was 328 K, being identical to the reported LCST of synthetic cis-1,4-polyisoprene/PB blend in our previous paper. The LCST of NR-gel/PB blend was quite similar to that of NR-sol/PB blend despite that NR-gel was crosslinked rubber (ν = 1.5 × 10 −6 ). Molecular weight was proved to produce no effect on the LCST phase behavior for high molecular weight polymer-polymer blend, i.e., NR/PB blend. KEY WORDS Natural Rubber / cis-1,4-polyisoprene / Polybutadiene / Blend / Miscibility / Lower Critical Solution Temperature (LCST) Phase Behavior / Miscibility and phase behavior of a pair of polymers, composed of carbon and hydrogen, is one of the most important phenomena to study the attractive forces 1-3 between dissimilar polymer chains, except for hydrogen bonding and charge transfer formations. To study these experimentally, a prudent selection of model polymers is important, because most high molecular weight hydrocarbons undergo crystallization or vitrification near ambient temperature, at which most experiments are carried out. We have investigated the miscibility and phase behavior for a blend of cis-1,4-polyisoprene (cis-1,4-PI) and polybutadiene (PB), which is regarded as liquid-like polymers, due to their low T g and T m 0 , i.e., below room temperature. In the previous study, 4 we found that PB with low 1,2 unit content was immiscible with cis-1,4-PI, whereas the reverse is found for PB with higher 1,2 unit content. The phase boundary between the miscible and immiscible state was at 32.3% 1,2 unit content, where the lower critical-solution-temperature (LCST) was observed to be 333 K for the blend. This phase transition was confirmed to take place reversibly and the mass transfer was proportional to the thermodynamic driving force, 5 T − T s , where T is the annealing temperature and T s is the spinodal temperature. Moreover, the extremely large negative excess volume on mixing 6 and free volume fraction apart from additive rule 7 were observed as well as a conformational change on mixing estimated from spin-lattice relaxation time measured by pulsed NMR spectroscopy. 8 These were proved positively by Roland, 9 Hasegawa, 10 Launger, 11 Bahani,12 and Roovers, 13 using various techniques respectively. However, the relationship between LCST and 1,2 unit content of PB, thus reported, was exclusively dependent upon the researchers. This was inferred to be due to the difference in molecular weight of the polymers, 12 despite that cis-1,4-PI and PB used in the previous works were hi...

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Section: Characterization Of Nr-sol Nr-gel and Pbsupporting

confidence: 83%

Lower Critical Solution Temperature Phase Behavior of Natural Rubber/Polybutadiene Blend

Kawahara

Asada

Isono

et al. 2002

Polym J

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“…Sample 7 was ozonized and reduced according to a literature procedure 17) . The following distribution of the styrene homosequences was obtained: 1S (6.0); 2S (2.…”

Section: Ozonolysis Of Samplementioning

confidence: 99%

Syndiotactic styrene-butadiene block copolymers synthesized with CpTiX3/MAO (Cp = C5H5, X = Cl, F; Cp = C5Me5, X = Me) and TiXn/MAO (n = 3, X = acac; n = 4, X = O-tert-Bu)

Zambelli¹,

Caprio

Grassi

et al. 2000

Macromol. Chem. Phys.

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“…12,13 The method was applied to the analysis of the sequence distribution of 1,2 units in polybutadiene by GPC measurement of ozonolysis products, which were transformed into trifluoroacetates after reductive degradation of the ozonide with LiAlH 4 . 14 A commercial polybutadiene showed GPC peaks corresponding to 1,4-1,4 and 1,4-(1,2) n -1,4 sequences from n ) 1 to 9 using a refractive index (RI) detector. However, the quantitative measurement of sequence distribution was not made due to the lack of information on the relative RI for each GPC peak.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Analysis of Sequence Length Distribution of 1,2 Units in Polybutadienes by Ozonolysis−GPC Method

et al. 1999

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The sequence distribution of 1,2 units in commercial and laboratory produced polybutadienes, containing 1,2 units from 0.5 to 87%, was analyzed by an ozonolysis−GPC method. Ozonides from polybutadiene were converted to trifluoroacetates by reduction with LiAlH4, followed by esterification with trifluoroacetic anhydride. The trifluoroacetates derived from 1,4−1,4 and 1,4−(1,2) n −1,4 sequences, from n = 1 to 7, were observed as respective GPC peaks using an refractive index detector. The relative intensities of these peaks were converted to the concentration of each sequence by using correction factors determined with model compounds and by direct weighing of each peak. Polybutadienes prepared by anionic polymerization showed a sequence distribution of 1,2 and 1,4 units corresponding to Bernoulian statistics, whereas the 1,4−(1,2)2−1,4 sequence was significantly higher than the theoretical value for 1,2 units in cis-1,4 polybutadiene.

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Analysis of the sequence distribution of 1,2 units in polybutadiene by an ozonolysis-GPC method

Cited by 9 publications

References 1 publication

Lower Critical Solution Temperature Phase Behavior of Natural Rubber/Polybutadiene Blend

Lower Critical Solution Temperature Phase Behavior of Natural Rubber/Polybutadiene Blend

Syndiotactic styrene-butadiene block copolymers synthesized with CpTiX3/MAO (Cp = C5H5, X = Cl, F; Cp = C5Me5, X = Me) and TiXn/MAO (n = 3, X = acac; n = 4, X = O-tert-Bu)

Quantitative Analysis of Sequence Length Distribution of 1,2 Units in Polybutadienes by Ozonolysis−GPC Method

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