Thermal weight loss of silica-poly(vinyl acetate) (PVAc) sol-gel composites

Beaudry, Christopher L.; Klein, Lisa C.; McCauley, Ronald A.

doi:10.1007/bf01979947

Cited by 12 publications

(2 citation statements)

References 19 publications

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“…This lowered mobility was due to hydrogen bonding between the carbonyl groups of PVAc and the hydroxyl groups of silica particles, resulting in the T g shift to higher temperatures. The presence of hydrogen bonds between the silanol groups on the silica particles and carbonyl groups of polymers such as PVAc, ,, PMMA, , and other methacrylate polymers has been reported using FTIR.…”

Section: Discussionmentioning

confidence: 99%

Structure of the Interfacial Region in Adsorbed Poly(vinyl acetate) on Silica

2015

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We performed a combined calorimetric and molecular modeling investigation of poly(vinyl acetate) (PVAc) on silica to characterize the intermolecular interactions and the behavior of the adsorbed polymer. From temperature-modulated differential scanning calorimetry experiments, different regions of thermal activity suggested a gradient of mobility in the adsorbed polymer. Polymer segments in more direct contact with silica (tightly bound) showed a significantly elevated and broadened glass transition relative to the bulk polymer, while polymer further away (loosely bound) showed only a slightly elevated transition relative to the bulk polymer. A thermal transition for PVAc at the air interface (more-mobile) was also observed and was at lower temperatures than the bulk polymer. Density profiles from molecular dynamics studies suggested a structure of the adsorbed polymer similar to that experimentally observed. These studies were consistent with the presence of a motional gradient in the polymer segments, and concomitant glass transition changes from the silica to the air interfaces. These results also demonstrate that hydrogen-bonding interactions, at the PVAc/silica interface, are critical to the high-temperature shifts in the glass transition. ■ INTRODUCTIONAdsorbed polymer−substrate interactions usually lead to differences in properties of bulk and adsorbed polymers. 1−10 Interactions between adsorbed polymers and solid surfaces have been shown to provide advantageous physical, mechanical, and thermal properties, making these materials suitable as lubricants, adhesives, coatings, and corrosion-resistant agents. 11−17 These properties are closely related to those that determine the glass transition, which for small amounts of adsorbed polymers depend on film thickness, polymer molecular mass, intermolecular interactions, and the mobility of macromolecular chains. 18−20 For example, the T g will be elevated if the interactions between the polymers and the substrate are attractive and strong. 21 Strong attractive interactions, covalent or hydrogen bonding, between polymer segments and the substrate can potentially reduce the mobility of the adsorbed polymer segments. This reduction in mobility due to restrictions from attachment points has been proposed as the main reason for T g elevation. 22−24 Differential scanning calorimetry (DSC) is the most common technique used to investigate thermal characteristics of bulk polymers and composites. 25−27 Temperature-modulated DSC (TMDSC) is a variant of DSC that, in addition to providing the same information as conventional DSC, provides additional insight into the thermal behavior of materials by separating the heat flow data into reversing and nonreversing events. 28,29 TMDSC and its derivatives have been used to resolve both weak and multicomponent transitions that would be difficult to distinguish in a conventional DSC scan. 30−34 Molecular dynamics (MD) simulations have also been used to investigate the dynamics and thermodynamics of thin-film polymer coatings. 35−5...

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Section: Discussionmentioning

confidence: 99%

Structure of the Interfacial Region in Adsorbed Poly(vinyl acetate) on Silica

2015

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“…These polymers are poly(N,N-dimethacrylamide), poly(2-methyl-2-oxazoline), poly(methyl methacrylate) (PMMA), polyvinylpyrrolidone (PVP), poly(acrylic acid) (PAA) and its copolymers, poly(vinyl acetate) (PVAc), and poly(vinyl alcohol) (PVA). [40][41][42][43] In detail, the properties of the hybrids are functions of the relative fractions of the polymer and TEOS in the sol-gel formulation, along with the chemistry and length of the polymer chain. When TEOS is polymerized in the presence of the polymer, the glass transition (T g ) of the polymer increases or becomes undetectable.…”

Section: Sequential Organic/inorganic Interpenetrating Networkmentioning

confidence: 99%

Transparent Organic/Inorganic Hybrid Gels: A Classification Scheme

Wójcik

Klein

1997

Appl. Organometal. Chem.

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Organo‐Silica Sol–Gel Materials

Avnir

Klein

Lévy

et al. 2009

Patai's Chemistry of Functional Groups

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Introduction The Silica Sol–Gel Process and Silica Sol–Gel Materials Direct Entrapment of Organic and Bioorganic Molecules in Sol–Gel Matrices Covalent Entrapment of Organic Functional Groups Organic/Inorganic Sol–Gel Copolymerizations Photochemistry, Photophysics and Optics of Doped Sol–Gel Materials Concluding Remark Acknowledgments

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Thermal weight loss of silica-poly(vinyl acetate) (PVAc) sol-gel composites

Cited by 12 publications

References 19 publications

Structure of the Interfacial Region in Adsorbed Poly(vinyl acetate) on Silica

Structure of the Interfacial Region in Adsorbed Poly(vinyl acetate) on Silica

Transparent Organic/Inorganic Hybrid Gels: A Classification Scheme

Organo‐Silica Sol–Gel Materials

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