Depth Profiling Study of Effect of Annealing Temperature on Polymer/Polymer Interfaces in Laminates Using Confocal Raman Microspectroscopy

1997 ◽  
Vol 51 (12) ◽  
pp. 1784-1790 ◽  
Author(s):  
Sohail Hajatdoost ◽  
Maurien Olsthoorn ◽  
Jack Yarwood
Keyword(s):  
Hydrogen Bonding ◽  
Annealing Temperature ◽  
Depth Profiling ◽  
Raman Microspectroscopy ◽  
Interfacial Region ◽  
Hydrogen Bonding Interaction ◽  
Bonding Interaction ◽  
Confocal Raman Microspectroscopy ◽  
Confocal Raman ◽  
Poly Acrylonitrile

The effect of annealing temperature on molecular interactions at the interface of polymer laminates is reported. Depth profiling has been carried out by using confocal Raman microspectroscopy to study poly(acrylonitrile)/poly(vinyl alcohol) (PAN/PVOH) and poly(acrylonitrile)/poly(acrylic acid) (PAN/PAA) laminates. The laminates have been annealed at 65, 75, and 90 °C. It is demonstrated that the degree of hydrogen-bonding interaction between the nitrile and alcohol groups near the interfacial region changes between laminates annealed at different temperatures. Increasing the annealing temperature up to near the glass transition temperature, Tg, of both polymers facilitates hydrogen bonding. However, above Tg, as a result of molecular flexibility, weakening of such interactions begins. Due to the lower molecular weight of PAA, and thus greater mobility in comparison with PVOH, the interfacial region of a PAN/PAA laminate is broader than that of a PAN/PVOH laminate. Hydrogen-bonding interaction between PAN and PAA was not observed. This result is rationalized by the hypothesis that, as a result of intramolecular interaction between the carbonyl and hydroxyl groups of PAA, formation of intermolecular hydrogen bonding has been hindered. In addition, the variations in the full width at half-height (FWHH) of the v(C≡N) band of a PAN–PVOH blend has been mapped by using the same technique.

Depth Profiling of Poly(Methyl Methacrylate), Poly(Vinyl Alcohol) Laminates by Confocal Raman Microspectroscopy

1996 ◽  
Vol 50 (5) ◽  
pp. 558-564 ◽  
Author(s):  
Sohail Hajatdoost ◽  
Jack Yarwood
Keyword(s):  
Depth Profiling ◽  
Raman Microspectroscopy ◽  
Poly Vinyl Alcohol ◽  
Interfacial Region ◽  
Hydrogen Bonding Interaction ◽  
Molecular Weights ◽  
Bonding Interaction ◽  
Molecular Depth Profiling ◽  
Confocal Raman Microspectroscopy ◽  
Confocal Raman

We report a molecular depth profiling study of a PMMA/PVOH laminate on quartz using confocal Raman microspectroscopy. It is demonstrated that this technique can be successfully employed to study the hydrogen-bonding interaction between the ester and alcohol groups near the interfacial region. The carbonyl, v(C=O), band of PMMA shows significant broadening in the interfacial region. Various PMMA/PVOH laminates with different PMMA molecular weights have been studied, and it is demonstrated that the PMMA layers with lower molecular weight show a greater degree of interpenetration for a given annealing time.

Correction of optical distortions in dry depth profiling with confocal Raman microspectroscopy

2011 ◽  
Vol 42 (6) ◽  
pp. 1330-1334 ◽  
Author(s):  
J. Pablo Tomba ◽  
María de la Paz Miguel ◽  
Claudio J. Perez
Keyword(s):  
Depth Profiling ◽  
Raman Microspectroscopy ◽  
Confocal Raman Microspectroscopy ◽  
Confocal Raman

Depth profiling of modified PVC surfaces using confocal Raman microspectroscopy

2000 ◽  
Vol 21 (13) ◽  
pp. 894-896 ◽  
Author(s):  
Javier Sacristán ◽  
Carmen Mijangos ◽  
Helmut Reinecke ◽  
Stephen Spells ◽  
Jack Yarwood
Keyword(s):  
Depth Profiling ◽  
Raman Microspectroscopy ◽  
Confocal Raman Microspectroscopy ◽  
Confocal Raman

Analysis of Depth Profiling Data Obtained by Confocal Raman Microspectroscopy

2003 ◽  
Vol 57 (9) ◽  
pp. 1123-1128 ◽  
Author(s):  
J. Vyörykkä ◽  
J. Paaso ◽  
M. Tenhunen ◽  
J. Tenhunen ◽  
H. Iitti ◽  
...  
Keyword(s):  
Depth Profiling ◽  
Raman Microspectroscopy ◽  
Confocal Raman Microspectroscopy ◽  
Confocal Raman

Radical Enzymes Control the Chemistry of Their Highly Reactive Intermediates Using the Quantum Coulombic Effect

2020 ◽  
Author(s):  
Hossein Khalilian ◽  
Gino A. DiLabio
Keyword(s):  
Hydrogen Bonding ◽  
Molecular Orbital ◽  
Reactive Intermediates ◽  
Hydrogen Bonding Interaction ◽  
Orbital Ordering ◽  
Dynamic Nature ◽  
Radical Intermediate ◽  
Highest Occupied Molecular Orbital ◽  
Bonding Interaction ◽  
Close Proximity

Here, we report an exquisite strategy that the B12 enzymes exploit to manipulate the reactivity of their radical intermediate (Adenosyl radical). Based on the quantum-mechanic calculations, these enzymes utilize a little known long-ranged through space quantum Coulombic effect (QCE). The QCE causes the radical to acquire an electronic structure that contradicts the Aufbau Principle: The singly-occupied molecular orbital (SOMO) is no longer the highest-occupied molecular orbital (HOMO) and the radical is unable to react with neighbouring substrates. The dynamic nature of the enzyme and its structure is expected to be such that the reactivity of the radical is not restored until it is moved into close proximity of the target substrate. We found that the hydrogen bonding interaction between the nearby conserved glutamate residue and the ribose ring of Adenosyl radical plays a crucial role in manipulating the orbital ordering

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