Which functional groups correspond to the characteristic peaks of the infrared spectrum (IR) of polyether polyols?

Which functional groups correspond to the characteristic peaks of the infrared spectrum (IR) of polyether polyols?

Polyether polyol is an important chemical raw material, which is widely used in polyurethane, coatings, adhesives and other fields. Its molecular structure contains rich functional groups, and infrared spectroscopy (IR) is one of the important tools to study the characteristics of these functional groups and their chemical bonds. In this paper, the infrared spectrum characteristic peaks of polyether polyols will be analyzed in detail to reveal their corresponding functional groups.

1. Hydroxyl (-OH) characteristic peak

Polyether polyols typically contain multiple hydroxyl functional groups in the molecule. The O-H stretching vibration of the hydroxyl group is an important characteristic peak in the infrared spectrum, which usually appears in the wave number range of 2500-3600 cm¹. The peak in this region is often referred to as the broad and strong "O-H stretching vibration peak". Specifically, the hydroxyl groups in polyether polyols can be divided into two categories: one is an alcoholic hydroxyl group attached to carbon (alcoholic -OH), and the other is an exchange hydroxyl group attached to ether oxygen (exchange -OH). The position of the infrared absorption peak of the two will be different, the absorption peak of the alcohol hydroxyl group is usually located at about 3600cm, while the absorption peak of the exchange hydroxyl group may be located between 2600 and 3000cm.

2. Ether bond (-O-) characteristic peak

Polyether polyol molecules also contain rich ether bond (-O-) structure. The C- O stretching vibration of the ether bond is another important characteristic peak of the infrared spectrum, which usually occurs in the wave number range of 1200-1300 cm¹. The peak intensity in this region is higher, and the peak shape is more symmetrical. C- O-C flexural vibrations of ether bonds may also occur in the wavenumber range of 600-800 cm¹. By analyzing the position and intensity of these characteristic peaks, the existence of ether bonds in the molecule can be effectively confirmed, and the structural characteristics of polyether polyols can be inferred.

3. Carbon-hydrogen bond (C-H) characteristic peak

In the infrared spectrum of polyether polyol, the vibration absorption peak of carbon-hydrogen bond may also appear. For example, the bending vibration of C- O-H bonds usually occurs in the wave number range of 1000-1200 cm¹. The peak in this region may be related to the C- O-H bond vibration near the hydroxyl group, and can also be used as an important basis for further analysis of the molecular structure.

4. Other possible characteristic peaks

In addition to the above-mentioned functional groups, some other characteristic peaks may appear in the infrared spectrum of the polyether polyol. For example, if the molecule contains double bonds or other heteroatoms, other absorption peaks may appear in the corresponding wave number range. For a typical polyether polyol molecule, the characteristic peaks of hydroxyl and ether bonds are the most significant and critical analytical basis.

5. Summary and analysis

Through the analysis of the characteristic peaks of the infrared spectrum of polyether polyols, the main functional groups in the molecule can be clearly identified, such as hydroxyl (-OH), ether bond (-O-) and so on. The position, intensity and morphological changes of these characteristic peaks can help researchers to further infer the molecular structure, judge the purity of molecules, and even be used for real-time monitoring in quality control and production process. Therefore, infrared spectrum analysis is of great significance in the research and application of polyether polyols.

The infrared spectrum characteristic peaks of polyether polyols are closely related to the functional groups in their molecular structures. Through systematic analysis and research, the chemical properties of polyether polyols and their performance in practical applications can be deeply understood.