Study of the acetoxy‐hydroxide transformation in ethylene‐vinyl acetate copolymers

Fonseca, C.; Fatou, J. G.; Pereña, José M.

doi:10.1002/apmc.1991.051900109

Cited by 11 publications

(2 citation statements)

References 23 publications

(2 reference statements)

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“…EVA polymer (Fig. 4(b)) is characterized by a strong band from the carbonyl group (CO) at 1720–1740 cm −1 and bands associated with CO at 1240 and 1010 cm −1 2, 12, 13 from poly(vinyl acetate), PVAc, sequences. CH x vibrations were also identified as indicated in the spectrum.…”

Section: Resultsmentioning

confidence: 99%

“…It should be emphasized that in EVA mortar systems, the presence of hydroxyl groups in EVA polymer is still more expressively associated with the hydrolysis of vinyl acetate sequences in the high pH medium characteristic of cement mortar 1, 2, 12, 13. Due to saponification, acetate groups from PVAc are partially or completely replaced by hydroxyls, thus resulting in poly(vinyl alcohol) sequences with pendantOH groups with the polyethylene sequences, remaining unaltered 13. Because of the attachment of OH groups to the EVA chain, the copolymer is thereby converted into a terpolymer (ethylene‐ter‐vinyl acetate‐ter‐vinyl alcohol), in turn increasing the polarity and the hydrophilicity of the latex (Fig.…”

Section: Resultsmentioning

confidence: 99%

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A Total Synthesis of Spirastrellolide A Methyl Ester

Andrejew

Benson

Schulthoff

et al. 2013

Chemistry A European J

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A concise total synthesis of spirastrellolide A methyl ester (1 a, R(1) =Me) as the parent compound of a series of highly cytotoxic marine macrolides is disclosed, which exploits and expands the flexibility of a synthesis plan previously developed by our group en route to the sister compound spirastrellolide F methyl ester (6 a, R(1) =Me). Key to success was the masking of the signature Δ(15,16) -bond of 1 a as a C16-carbonyl group until after the stereogenic center at C24 had been properly set by a highly selective hydrogenation of the C24 exo-methylene precursor 66. Conformational control over the macrocyclic frame allowed the proper stereochemical course to be dialed into this reduction process. The elaboration of the C16 ketone to the C15-C16 double bond was accomplished by a chemoselective alkenyl triflate formation followed by a palladium-catalyzed hydride delivery. The role of the ketone at C16 as a strategic design element is also evident up-stream of the key intermediate 66, the assembly of which hinged upon the addition of the polyfunctionalized dithiane 37 to the similarly elaborate aldehyde fragment 46. Other crucial steps of the total synthesis were an alkyl-Suzuki coupling and a Yamaguchi lactonization that allowed the Northern and the Southern sector of the target to be stitched together and the macrocyclic perimeter to be forged. The lateral chain comprising the remote C46 stereocenter was finally attached to the core region by a modified Julia-Kocienski olefination. The preparation of the individual building blocks led to some methodological spin-offs, amongst which the improved procedure for the N-O-bond cleavage of isoxazolines by zero-valent molybdenum and the ozonolysis of a double bond in the presence of other oxidation-prone functionality are most noteworthy. Preliminary biological data suggest that the entire carbon framework, that is the macrocyclic core plus the lateral chain, might be necessary for high cytotoxicity.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

A Total Synthesis of Spirastrellolide A Methyl Ester

Andrejew

Benson

Schulthoff

et al. 2013

Chemistry A European J

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Polyethylene graft copolymers with a liquid crystalline component in the side chains

Pinto¹,

Gomes²,

Soares³

1996

Macro Chemistry & Physics

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An ethylene-vinyl acetate copolymer (EVA) was chemically modified by the introduction of pendent thiol groups (EVA-SH) suitable for chain transfer. The resulting copolymer was grafted with 4-phenylazophenyl4-(4-acryloyloxybutoxy)benzoate, a liquid crystalline monomer (LCM), initiated by AIBN. Grafting was performed at LCMEVA-SH mass ratios of 10, 5, 2 and 1 in the feed. The grafting degree, i.e., the fraction of LC polymer in the graft copolymer, ranged from ca. 5-30 wt.-%. The thermal transitions were investigated by DSC, pointing at marked microphase separation between LC and polyethylene moieties. The anisotropic properties of the graft copolymers were confirmed by cross-polarized light microscopy. All the samples showed birefringence at 140"C, some only on shearing however.

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Porcelain tile surface modification with isocyanate coupling agent: interactions between EVA modified mortar and silane improving adherence

Nascimento

Oréfice

Mansur

2011

Surface & Interface Analysis

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Adhesion between tiles and mortar is of paramount importance to the overall stability of ceramic tile systems. The interfaces between ceramic tiles and polymer-modified Portland cement mortar are derived from several physical and chemical phenomena that take place during their formation. From the chemical perspective, weak forces are expected to occur preferably at the tiles and polymer-modified Portland cement mortar interfaces. Therefore, the purpose of this study was to promote a new chemical functionalization of ceramic tile surfaces by modifying with isocyanate-trialkoxysilane coupling agent in order to enhance the interfacial adhesion with poly (ethylene-co-vinyl acetate), EVA, polymer-modified mortar. Pull-off tests and Fourier Transformed Infrared Spectroscopy (FTIR), using the Attenuated Total Reflectance method, were carried out in order to characterize the system. The bond strength results have provided evidence toward improvements in adherence at the tile-polymer modified mortar interface, thus reflecting the development of urethane linkages between silane and EVA polymer, as detected by FTIR.

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Study of the acetoxy‐hydroxide transformation in ethylene‐vinyl acetate copolymers

Cited by 11 publications

References 23 publications

A Total Synthesis of Spirastrellolide A Methyl Ester

A Total Synthesis of Spirastrellolide A Methyl Ester

Polyethylene graft copolymers with a liquid crystalline component in the side chains

Porcelain tile surface modification with isocyanate coupling agent: interactions between EVA modified mortar and silane improving adherence

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