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Hydrogen bonding in lignin: a Fourier transform infrared model compound study
1Biomaterials Chemistry, Department of Wood Science, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Biomacromolecules
|September 13, 2005
Summary
Aliphatic hydroxyl groups in lignin form stronger hydrogen bonds than phenolic ones. Dimeric lignin structures exhibit stronger intermolecular bonding, influencing biopolymer properties.
Area of Science:
- Biochemistry
- Polymer Science
- Spectroscopy
Background:
- Hydrogen bonding significantly impacts the thermal and mechanical properties of biopolymers.
- Lignin, an abundant plant biopolymer, possesses a complex hydrogen-bonding network crucial for its characteristics.
Purpose of the Study:
- To investigate and characterize hydrogen bond formation in lignin using model compounds.
- To correlate hydrogen bonding patterns with the properties of technical lignins from different wood sources.
Main Methods:
- Fourier transform infrared (FTIR) spectroscopy was employed to analyze various lignin model compounds.
- Four monomeric and one dimeric lignin model compounds were studied under diverse conditions.
Main Results:
- FTIR analysis indicated that aliphatic hydroxyl groups form stronger hydrogen bonds compared to phenolic hydroxyl groups.
- A dimeric biphenyl-type lignin structure demonstrated significantly stronger intermolecular hydrogen bonds than monomeric models.
- These findings help explain the complex hydrogen-bonding systems observed in softwood and hardwood technical lignins.
Conclusions:
- The study elucidates the differential hydrogen bonding strengths of hydroxyl groups in lignin.
- Differences in hydrogen bonding between hardwood and softwood lignin correlate with observed variations in their glass transition temperatures.