Urethane — FTIR absorption peaks and assignments

Quick answer

Urethane is usually assigned by looking for a recurring cluster of characteristic peaks rather than one exact textbook number. The table below shows where the literature most often places this group in FTIR, ranked by accumulated evidence.

Characteristic FTIR peaks for Urethane

Showing the 30 best-supported peaks of 78 total for Urethane.

Spectrum logic

A functional-group assignment becomes more confident when several expected bands appear together. Use this page to find the strongest-supported peaks, then confirm that the same sample exhibits a coherent pattern rather than a single isolated hit.

Real-world usage

These pages are useful for unknown material analysis, peak explanation in reports, polymer troubleshooting, and verifying whether a candidate material family is chemically plausible.

Common mistakes

• Using one functional-group page as a complete material verdict without checking the rest of the spectrum.
• Assuming the strongest band is always the most diagnostic one.
• Forgetting that processing, additives, aging, and mixtures can shift or broaden expected peaks.

Verification advice

Use DSC, GC-MS, or TGA when several material families share similar bands or when mixture effects make the FTIR assignment uncertain.

Literature behind these assignments

• 1698 cm⁻¹ confidence 1.0

  “The peaks at 1698cm-1 and correspond to the urethane carbonyl, and hydrogen”

  Two-component waterborne polyurethane_ Curing process study using dynamic in situ IR spectroscopy DOI: 10.1016/j.polymertesting.2018.05.021
• 1725 cm⁻¹ confidence 1.0

  “All spectra are cm-1, characterized by a major band centred at 1725 ascribed to the cm-1, free C O urethane groups, and another peak at about 1700”

  Hydrogen bonding and thermomechanical properties of model polydimethylsiloxane based poly(urethane-urea) copolymers: Effect of hard segment content DOI: 10.1016/j.porgcoat.2015.06.015
• 1081 cm⁻¹ confidence 1.0

  “Moreover, the weak adsorption band at 1081.34 is related to symmetric stretching in cm(cid:0) 1 P-CH3 the urethane group [3,37,61,79,83].”

  Biologically-induced synthetic manganese carbonate precipitate (BISMCP) for potential applications in heavy metal removal DOI: 10.1016/j.heliyon.2023.e15919
• 3317 cm⁻¹ confidence 1.0

  “The cm-1 FT-IR spectrum of semi-rigid PU shows the existence of absorption at 3317 corresponding to the N-H stretching vibration of urethane function.”

  Preparation of one-shot and two-shot method of semi-rigid polyurethane film based on functionalized liquid natural rubber DOI: 10.1063/1.5047200
• 3317 cm⁻¹ confidence 1.0

  “1, the key feature of the fully formed semi-rigid PU is the absorption band cm-1 at 3317 corresponding to the urethane N-H”

  The behavior of semi-rigid polyurethane film based on functionalized rubber by one-shot and two-shot method preparation DOI: 10.1007/s10853-018-2578-8
• 1537 cm⁻¹ confidence 1.0

  “tense stretching peak at 1730 cm-1 corresponding to carbonyl groups (C=O), an amide Nthermal, morphological, and physical properties of the EQUIA coat with and without H absorption band at 1537 cm-1 was observed due to the presence of ureth”

  Structural, Physical, and Mechanical Analysis of ZnO and TiO2 Nanoparticle-Reinforced Self-Adhesive Coating Restorative Material DOI: 10.3390/ma14247507
• 1537 cm⁻¹ confidence 1.0

  “LLM confirmed rule peak-group candidate”

  A study of molecular architectural dynamics of crosslinked urethane during photo-aging by two-dimensional infrared correlation spectroscopy DOI: 10.1016/j.polymdegradstab.2020.109242
• 1729 cm⁻¹ confidence 1.0

  “LLM confirmed rule peak-group candidate”

  Jana 等 - 2009 - Molecular Orientation of Polyurethane Based Liquid DOI: 10.1080/10601320903158719