Related Experiment Video
Updated: Jul 20, 2026
11:49
Synthesis of Soft Polysiloxane-urea Elastomers for Intraocular Lens Application
Published on: March 8, 2019
Humidity-dependent dynamic infrared linear dichroism study of a poly(ester urethane)
Jon R Schoonover1, Warren P Steckle, Jonathan D Cox
1Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA. schoons@lanl.gov
Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
|September 5, 2006
Summary
Humidity significantly impacts poly(ester urethane) by altering hydrogen bonding and functional group orientation. Water absorption changes the polymer
Area of Science:
- Polymer Science
- Materials Science
- Spectroscopy
Background:
- Poly(ester urethane) is a widely used material susceptible to environmental changes.
- Understanding humidity's effects is crucial for predicting material performance and longevity.
- Water absorption can alter polymer structure and properties.
Purpose of the Study:
- To investigate the impact of humidity and water absorption on poly(ester urethane).
- To analyze changes in hydrogen bonding and functional group orientation under varying humidity levels.
- To elucidate the relationship between water content and polymer micro-environments.
Main Methods:
- Utilized Fourier transform infrared (FTIR) techniques, including infrared difference spectroscopy.
- Employed dynamic infrared linear dichroism (DIRLD) in tensile deformation mode.
- Measured infrared spectra and weight changes using an environmental infrared microbalance cell during absorption-desorption cycles.
Main Results:
- Infrared difference spectroscopy revealed that humidity affects hydrogen-bonding interactions within the polymer.
- DIRLD studies demonstrated that water content influences the orientational response of functional groups.
- Complex humidity-dependent behavior was observed for hydrogen-bonding functional groups, indicating altered micro-environments.
Conclusions:
- Humidity and water absorption significantly modify the hydrogen bonding network and molecular orientation in poly(ester urethane).
- The study provides insights into the micro-environmental changes induced by water within the polymer matrix.
- These findings are essential for material design and application in humid environments.
Related Concept Videos
01:29UV–Vis Spectroscopy: Woodward–Fieser Rules
UV–Visible absorption spectra of conjugated dienes arise from the lowest energy π → π* transitions. The light-absorbing part of the molecule is called the chromophore, and the substituents directly attached to the chromophore are called auxochromes. A strong correlation exists between the absorption maxima, λmax, and the structure of a conjugated π system. The Woodward–Fieser rules predict the value of λmax for a given structure by adding the contributions...
01:28IR and UV–Vis Spectroscopy of Carboxylic Acids
In IR spectroscopy of carboxylic acids, the C=O bond shows a characteristic band between 1710 and 1760 cm⁻¹, and the O–H bond exhibits a broad band between 2500 and 3300 cm⁻¹.
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
01:28Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
01:29IR and UV–Vis Spectroscopy of Aldehydes and Ketones
Infrared spectroscopy, also known as vibrational spectroscopy, is mainly used to determine the types of bonds and functional groups in molecules. In aldehydes and ketones, the carbonyl (C=O) bond shows an absorption around 1710 cm-1. The C=O bond vibration of an aldehyde occurs at lower frequencies than that of a ketone. In addition to the C=O absorption in an aldehyde, the aldehydic C–H bond also gives two peaks in the 2700–2800 cm-1 range. This absorption, coupled with the C=O stretching, is...
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
01:32UV–Vis Spectroscopy of Conjugated Systems
Organic compounds with conjugated double bonds show strong absorption features in the UV–visible region of the electromagnetic spectrum attributed to π → π* electronic excitations. Generally, a UV–vis absorption spectrum is recorded as a plot of absorbance vs wavelength. The wavelength of maximum absorbance, which manifests as a peak in the absorption spectrum, is denoted as λmax.
One of the factors influencing λmax is the extent of conjugation in the...
One of the factors influencing λmax is the extent of conjugation in the...