Quantitative Determination of Ethylene Epoxide, Propylene Epoxide, and Higher Molecular Weight Epoxides Using Dodecanethiol

Gudzinowicz, B. J.

doi:10.1021/ac60167a039

Cited by 15 publications

(3 citation statements)

References 15 publications

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“…The two signals at 1665 (II) and 1635 cm -1 (III), evident in scan set (b) and very strong in spectrum (c), can be assigned to 2,4,4-trimethylpentanal-1 (TMPA-1) and TMPA-1 complexed with TiCl 4 (TMPA-1→TiCl 4 ), respectively. The isomerization of epoxides by Lewis acids is a well-known reaction, , while complexation with TiCl 4 was shown to shift the carbonyl stretch of aldehydes (1765−1645 cm -1 ) to lower wavenumbers. , The broad band at 1100 cm -1 (IV) that appears in spectrum (c) is typical of polyethers, forming by self-polymerization of the TMPO-1 and which is considered to be a side reaction in terms of the proposed mechanism (Scheme ). These reactions proceeded simultaneously and none proceeded to completion, most likely due to the limited amount of TiCl 4 available.…”

Section: Resultsmentioning

confidence: 99%

Real-Time Mid-IR Monitoring of the Initiation and Propagation in Epoxi-Initiated Living Isobutylene Polymerizations

2000

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The initiation and propagation of isobutylene (IB) polymerization initiated by 1,2-epoxi-2,4,4-trimethylpentane (TMPO-1)/TiCl 4 was monitored by a new fiber-optic transmission mid-IR probe. The real-time IR data provided insight into the initiation mechanism. Polyether formation, isomerization of the TMPO-1 into 2,4,4-trimethylpentanal, and its complexation by TiCl4 were observed, which occurred simultaneously with initiation of IB polymerization. The proposed initiating mechanism involves the formation of tertiary carbocations, which has been claimed to occur in the cationic polymerization of epoxides by the SN1 mechanism. On the basis of our results, the competitive occurrence of both SN1 and SN2 pathways is proposed. Interestingly, ketone/TiCl4 systems were found to initiate IB polymerization, albeit with very low efficiency. IR monitoring of these systems gave additional insight into the initiating mechanism. IB polymerization was monitored by following the disappearance of the second overtone of the C-H wag in the dCH2 group in IB at 1780 cm -1 and the CdC stretch at 1655 cm -1 . The linearity of first-order monomer consumption plots and the production of nearly uniform polyisobutylenes (PIBs) (Mw/Mn ) 1.06-1.13) indicated living conditions.

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Section: Resultsmentioning

confidence: 99%

Real-Time Mid-IR Monitoring of the Initiation and Propagation in Epoxi-Initiated Living Isobutylene Polymerizations

2000

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“…The solvent was evaporated at 25 °C for 24 h (1 atm). It is worth noting that DT does not react to DGEBA at room temperature due to the absence of a strong base capable of abstracting the proton − SH from DT 34 (pK a values for DT = 11; AEP = 9.5; m-XDA = 9). The final stage of drying was at 25 °C for 2 h under vacuum (∼1.10 −3 Torr) to evaporate DT 35 (vapor pressure of 2.5 Torr at 25 °C).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

High-Energy Dissipation Performance in Epoxy Coatings by the Synergistic Effect of Carbon Nanotube/Block Copolymer Conjugates

Garate

Bianchi

Pietrasanta

et al. 2016

ACS Appl. Mater. Interfaces

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Hierarchical assembly of hard/soft nanoparticles holds great potential as reinforcements for polymer nanocomposites with tailored properties. Here, we present a facile strategy to integrate polystyrene-grafted carbon nanotubes (PSgCNT) (0.05-0.3 wt %) and poly(styrene-b-[isoprene-ran-epoxyisoprene]-b-styrene) block copolymer (10 wt %) into epoxy coatings using an ultrasound-assisted noncovalent functionalization process. The method leads to cured nanocomposites with core-shell block copolymer (BCP) nanodomains which are associated with carbon nanotubes (CNT) giving rise to CNT-BCP hybrid structures. Nanocomposite energy dissipation and reduced Young's Modulus (E*) is determined from force-distance curves by atomic force microscopy operating in the PeakForce QNM imaging mode and compared to thermosets modified with BCP and purified carbon nanotubes (pCNT). Remarkably, nanocomposites bearing PSgCNT-BCP conjugates display an increase in energy dissipation of up to 7.1-fold with respect to neat epoxy and 53% more than materials prepared with pCNT and BCP at the same CNT load (0.3 wt %), while reduced Young's Modulus shows no significant change with CNT type and increases up to 25% compared to neat epoxy E* at a CNT load of 0.3 wt %. The energy dissipation performance of nanocomposites is also reflected by the lower wear coefficients of materials with PSgCNT and BCP compared to those with pCNT and BCP, as determined by abrasion tests. Furthermore, scanning electron microscopy (SEM) images taken on wear surfaces show that materials incorporating PSgCNT and BCP exhibit much more surface deformation under shear forces in agreement with their higher ability to dissipate more energy before particle release. We propose that the synergistic effect observed in energy dissipation arises from hierarchical assembly of PSgCNT and BCP within the epoxy matrix and provides clues that the CNT-BCP interface has a significant role in the mechanisms of energy dissipation of epoxy coating modified by CNT-BCP conjugates. These findings provide a means to design epoxy-based coatings with high-energy dissipation performance.

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“…(3) The difficulties encountered with oxirans which rearrange to carbonyl compounds in acidic medium have been described in Chapter 2. Gudzinowicz (4) reported satisfactory results when his "dodecanethiol" method was used with styrene oxide, which is notorious for its tendency to undergo rearrangements, and Sully developed a "sodium thiosulphate" method for the analysis of the same epoxide. (5) Such methods are unlikely to be very useful with less reactive highly substituted epoxides such as l,2-epoxy-2,4,4trimethylpentane, however; for these, a "rearrangement" method seems preferable.…”

Section: General Commentsmentioning

confidence: 99%

Other Methods for Epoxide Determination

Dobinson¹,

Hofmann²,

Stark³

1969

The Determination of Epoxide Groups

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Quantitative Determination of Ethylene Epoxide, Propylene Epoxide, and Higher Molecular Weight Epoxides Using Dodecanethiol

Cited by 15 publications

References 15 publications

Real-Time Mid-IR Monitoring of the Initiation and Propagation in Epoxi-Initiated Living Isobutylene Polymerizations

Real-Time Mid-IR Monitoring of the Initiation and Propagation in Epoxi-Initiated Living Isobutylene Polymerizations

High-Energy Dissipation Performance in Epoxy Coatings by the Synergistic Effect of Carbon Nanotube/Block Copolymer Conjugates

Other Methods for Epoxide Determination

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