NMR Studies of Organic Thin films

Blum, Frank D.

doi:10.1016/s0066-4103(08)60094-0

Cited by 26 publications

(29 citation statements)

References 187 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The properties of polymers at interfaces are usually different from the properties of bulk polymers. − In the presence of air, small amounts of adsorbed polymers on solid substrates may be affected by both polymer/substrate and polymer/air interfaces. Previous studies of adsorbed polymers have shown a motional heterogeneity for polymers at interfaces with attractive interactions with substrates. − This heterogeneity may include more-mobile segments at the air interface, less-mobile segments , referred to as tightly bound , near the substrate, and bulk-like segments between them. As an example, it has been shown that there were three different regions of thermal activity corresponding to interfacial layers for adsorbed high molecular mass poly(vinyl acetate) (PVAc) on silica. , Hydrogen bonding between the polymer side-chain carbonyl groups and hydroxyl groups of the silica surface has been identified as a strong contributing factor in the reduction of mobility and the elevation of glass transition temperature ( T g ). − …”

Section: Introductionmentioning

confidence: 99%

Surface Bonding Is Stronger for Poly(methyl methacrylate) than for Poly(vinyl acetate)

2016

View full text Add to dashboard Cite

Polymer−substrate interactions can directly affect the thermal properties of adsorbed polymers, such as the glass transition temperature. Using temperature-modulated differential scanning calorimetry (TMDSC) and molecular modeling, we performed direct comparisons of the thermal properties and intermolecular interactions of adsorbed poly-(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA) with similar molecular masses and adsorbed amounts on silica. Compared to their bulk counterparts, adsorbed PMMA showed a larger change in glass transition and a larger amount of tightly bound polymer compared to adsorbed PVAc. These observations suggested that the interactions between PMMA and silica were stronger than those between PVAc and silica. Molecular modeling of these surface-adsorbed polymers showed that PMMA associates more strongly with silica than does PVAc through additional hydrogen-bonding interactions. Additionally, simulations show that the polymer−polymer interactions are stronger in PMMA than PVAc, helping explain why a PMMA mobile component is not observed in TMDSC thermograms.

show abstract

Section: Introductionmentioning

confidence: 99%

Surface Bonding Is Stronger for Poly(methyl methacrylate) than for Poly(vinyl acetate)

2016

View full text Add to dashboard Cite

show abstract

“…Solid-state NMR has progressed to the point where high-resolution spectra of strongly dipolar-coupled protons are obtainable, even for thin surface layers. 13,14 Magic-angle spinning (MAS) at rates up to 35 kHz is capable of averaging to zero most of the dipolar couplings that normally broaden 1 H NMR spectra beyond usefulness. Additionally, the observation of protons eliminates the reliance on the isotopic enrichment that facilitates the observation of heteronuclei.…”

Section: Introductionmentioning

confidence: 99%

NMR Studies of the Effect of Adsorbed Water on Polyelectrolyte Multilayer Films in the Solid State

et al. 2003

View full text Add to dashboard Cite

Fast-MAS 1 H NMR is used to probe the structure and dynamics of the adsorbed water and polymer components in polyelectrolyte multilayer (PEM) films and the bulk polyelectrolyte complex (PEC). The films, ranging in size from a single layer to 5 bilayers, consist of poly(diallyl dimethylammonium chloride), PDADMAC, and poly(sodium-4-styrenesulfonate), PSS, adsorbed onto colloidal silica. Relaxation and line width measurements show that the adsorbed water is less mobile in the films than in the analogous PEC. The environment of the water throughout the film is found to be affected by the nature of the outer layer with the water displaying a higher mobility and chemical shift when PDADMAC forms the outer layer. Relaxation measurements, together with 1 H double-quantum (DQ) NMR experiments, reveal that polymer dynamics in the PEMs are strongly influenced by the layer number and water content. 2D spin diffusion and DQ NMR are used to detect polymer-polymer and water-polymer association. The results support the diffuse interpenetrating model of the different layers and a partitioning of the water to the PSS component and to the surface layer.

show abstract

“…It is well-known that the line shape of a deuterium solidecho spectrum is governed by molecular motions. [20][21][22][23][24][25] * To whom correspondence should be addressed at the University of MissourisRolla. E-mail: fblum@umr.edu.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the Interface in Polymer−Silica Composites Containing an Acrylic Silane Coupling Agent

and

Blum

1999

Chem. Mater.

View full text Add to dashboard Cite

Microscopic dynamics of the interfacial layer and macroscopic mechanical properties of [3-(acryloxy)propyl]trimethoxysilane (APMS) at a polymer-silica interface were studied using NMR and three-point bending tests. Wide-line deuterium NMR studies of deuterium-enriched [3-(acryloxy)propyl]trimethoxysilane-d (APMS-d), showed that when chemically bonded to silica, the acrylic group of APMS moved rapidly at the interface with air, more slowly when coated with a poly(methyl methacrylate) (PMMA) overlayer, and slowest when copolymerized with methyl methacrylate. A two-component line shape was found for the coated composite and these were assigned to relative immobile and mobile surface groups. From three-point bend tests, the PMMA/glass-fiber composite, made from glass laminates treated with APMS, had almost two times the flexural strength of a composite made from glass laminates not treated with APMS. Electron micrographs of the fracture surfaces revealed that the untreated fibers were smooth, while those from the APMS-treated glass were rougher, indicating the presence of polymer at the interface.

show abstract

NMR Studies of Organic Thin films

Cited by 26 publications

References 187 publications

Surface Bonding Is Stronger for Poly(methyl methacrylate) than for Poly(vinyl acetate)

Surface Bonding Is Stronger for Poly(methyl methacrylate) than for Poly(vinyl acetate)

NMR Studies of the Effect of Adsorbed Water on Polyelectrolyte Multilayer Films in the Solid State

Characterization of the Interface in Polymer−Silica Composites Containing an Acrylic Silane Coupling Agent

Contact Info

Product

Resources

About