Self-association through hydrogen bonding and sequence distribution in poly(vinyl acetate-co-vinyl alcohol) copolymers

Garnaik, Baijayantimala; Thombre, Sunita M.

doi:10.1002/(sici)1097-4628(19990404)72:1<123::aid-app13>3.0.co;2-n

Cited by 11 publications

(5 citation statements)

References 21 publications

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“…Nuclear Magnetic Resonance. 1 H and 13 C NMR spectra were recorded on a Bruker ARX300 spectrometer using CDCl3 and DMSO solvent for the pure PAS and PVPh-co-PAS copolymers, respectively. Gel Permeation Chromatography (GPC).…”

Section: Methodsmentioning

confidence: 87%

“…Earlier studies [7][8][9][10][11][12][13] have found that the copolymers of vinyl alcohol and vinyl acetate (PVA-co-PVAc) prepared from the acidic hydrolysis tend to be more randomly distributed than those obtained from basic solution, suggesting that kinetics of basic hydrolysis of the PVAc is a neighboring group catalytic process superimposed on a general electrostatic effect. Therefore, the probability of hydrolyzing neighboring acetyl groups in basic conditions is significantly higher.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Hydrolysis on the Strength of Hydrogen Bonds and T_g of Poly(vinylphenol-co-acetoxystyrene)

2003

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A series of poly(vinylphenol-co-acetoxystyrene) (PVPh-co-PAS) copolymers were prepared by partial hydrolyses of poly(acetoxystyrene) (PAS) in acidic and basic solutions. Higher glass transition temperature, higher fraction of hydrogen-bonded carbonyl group, and higher interassociation equilibrium constant were observed for copolymers with same composition prepared from the acidic hydrolysis than from the basic hydrolysis because the sequence distribution of the former is relatively more random than the latter. Infrared spectra provide positive evidence in terms of sequence distribution, glass transition temperature, and hydrogen-bonding strength in poly(vinylphenol-co-acetoxystyrene) by prepared these two hydrolysis methods.

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Section: Methodsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Effect of Hydrolysis on the Strength of Hydrogen Bonds and T_g of Poly(vinylphenol-co-acetoxystyrene)

2003

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“…Therefore, H-bonds are formed not only between two or more hydroxyl groups but also between an OH group of VA unit and an oxygen atom of VAc unit, in agreement with the literature data. 55,56 From our data, it is not possible to conclude, which of two oxygen atoms in acetyloxy group is preferentially involved into H-bonding and quantum chemistry calculations should be applied here. In any case, if VAc and VA units are chain neighbors, then they can form a hydrogen bond leading to a thermally stable 6-or 8-member ring.…”

Section: ■ Introductionmentioning

confidence: 57%

Effect of Chain Structure on the Rheological Properties of Vinyl Acetate–Vinyl Alcohol Copolymers in Solution and Bulk

et al. 2014

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Bulk and solution studies revealed a strongly pronounced effect of chain structure on the rheological and relaxation behavior of wellcharacterized vinyl acetate−vinyl alcohol copolymers of similar composition and polymerization degree. The frequency−temperature superposition principle is fully applicable to the random copolymers, which demonstrate all expected relaxation states, whereas a divergence of the reduced dynamic moduli−frequency dependences is observed for the multiblock copolymers. In the latter case, the terminal zone is sensitive to the self-assembling of vinyl alcohol blocks into (depending on the copolymer composition) crystalline or amorphous microstructures. The monomer unit distribution particularly affects properties of the copolymer solutions in N,Ndimethylformamide (DMF). 5% solutions behave as simple viscoelastic liquids at 20°C and show viscoplastic behavior at −20°C, where more blocky chains are characterized by up to 4 orders of magnitude higher yield stress values. The multiblock copolymer solutions demonstrate a pronounced viscosity hysteresis in the heating−cooling cycle, being absent in the random copolymers. 10% solutions of multiblock copolymers are practically gelatinous even at room temperature. The observed effects are explained by examining the peculiarities of hydrogen bonding in vinyl acetate−vinyl alcohol copolymers using FTIR spectroscopy. The multiblock copolymers are characterized by stronger hydroxyl−hydroxyl H-bonds and greater fraction of interchain hydroxyl−acetyloxy H-bonds providing aggregation of chains and high viscosity of the corresponding samples, whereas the random copolymers more strongly interact with the residual solvent. Dynamic light scattering studies prove that the relaxation of concentration fluctuations is completely diffusive, being bimodal in the random copolymers and trimodal in the multiblock ones. The fast mode in the latter case demonstrates anomalous concentration behavior. In the dilute regime, up to very low concentrations, multiblock copolymer chains form stable aggregates, and this fact correlates with an unusual growth of the reduced viscosity in the corresponding rheological experiments.

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“…This composition is the most tensile resistant with a force of 182 N and a maximum stress of 73.16 MPa, the most exible (E = 955 MPa) and the most ductile (εr = 768 %). From these results, it can be deduced that the incorporation of the clay into the PVAc matrix, with different percentages, has signi cantly improved all of its tensile properties [48].…”

Section: Mechanical Properties Of Polymermentioning

confidence: 93%

Green Anionic polymerization of vinyl acetate using Maghnite-Na + (Algerian MMT): Synthesis characterization and reactional mechanism

Cherifi¹,

Belbachir²,

Rahmouni³

2021

Preprint

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In this work, the green polymerization of vinyl acetate is carried out by a new method which consists in the use of clay called Maghnite-Na + as an ecological catalyst, non-toxic, inexpensive and recyclable by simple filtration. X-ray diffraction (XRD) showed that Maghnite-Na + is successfully obtained after cationic treatment (sodium) on raw Maghnite. It is an effective alternative to replace toxic catalysts such as benzoyl peroxide (BPO) and Azobisisobutyronitrile (AIBN) which are mostly used during the synthesis of polyvinyl acetate (PVAc) making the polymerization reaction less problematic for the environment. The synthesis reaction is less energetic by the use of recycled polyurethane as container for the reaction mixture and which is considered as a renewable material and a good thermal insulator which maintains the temperature at 0°C for 6h. The reaction in bulk is also preferred to avoid the use of a solvent and therefore to stay in the context of green chemistry. In these conditions, the structure of obtained polymer is established by Nuclear Magnetic Resonance Spectroscopy 1H NMR and 13C NMR. Infrared spectroscopy (FT-IR) is also used to confirm the structure of PVAc. Thermogravimetric analysis (TGA) showed that it is thermally stable and it starts to degrade from 330°C while Differential Scanning calorimetry (DSC) shows that this polymer has a glass transition temperature (Tg = 50°C). The composition in PVAc/maghnite-Na+ (7wt% of catalyst) is the most tensile resistant with a force of 182 N and a maximum stress of 73.16 MPa, the most flexible (E = 955 MPa) and the most ductile (εr = 768 %)

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Self-association through hydrogen bonding and sequence distribution in poly(vinyl acetate-co-vinyl alcohol) copolymers

Cited by 11 publications

References 21 publications

Effect of Hydrolysis on the Strength of Hydrogen Bonds and T_g of Poly(vinylphenol-co-acetoxystyrene)

Effect of Hydrolysis on the Strength of Hydrogen Bonds and T_g of Poly(vinylphenol-co-acetoxystyrene)

Effect of Chain Structure on the Rheological Properties of Vinyl Acetate–Vinyl Alcohol Copolymers in Solution and Bulk

Green Anionic polymerization of vinyl acetate using Maghnite-Na + (Algerian MMT): Synthesis characterization and reactional mechanism

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Self-association through hydrogen bonding and sequence distribution in poly(vinyl acetate-co-vinyl alcohol) copolymers

Cited by 11 publications

References 21 publications

Effect of Hydrolysis on the Strength of Hydrogen Bonds and Tg of Poly(vinylphenol-co-acetoxystyrene)

Effect of Hydrolysis on the Strength of Hydrogen Bonds and Tg of Poly(vinylphenol-co-acetoxystyrene)

Effect of Chain Structure on the Rheological Properties of Vinyl Acetate–Vinyl Alcohol Copolymers in Solution and Bulk

Green Anionic polymerization of vinyl acetate using Maghnite-Na + (Algerian MMT): Synthesis characterization and reactional mechanism

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Effect of Hydrolysis on the Strength of Hydrogen Bonds and T_g of Poly(vinylphenol-co-acetoxystyrene)

Effect of Hydrolysis on the Strength of Hydrogen Bonds and T_g of Poly(vinylphenol-co-acetoxystyrene)