Low-Frequency Raman Spectroscopy of Polymers

Abstract

Low-frequency Raman (LFR) spectroscopy has become a valuable tool for investigating structural properties of polymeric materials. This spectral region, typically below 200 cm⁻¹, provides critical information about intermolecular interactions, lattice vibrations, and phonon modes that define polymer structure. Recent advances in laser line rejection and computational techniques have improved LFR's accessibility and analytical precision. This review explores key applications of LFR for polymer characterization, such as determining crystallinity, identifying phase transitions, and investigating hydrogen bonding. How LFR provides unique insights into the structural dynamics of amorphous and semicrystalline polymers, including interchain interactions, lamella thickness effects, and tacticity is also discussed. Moreover, LFR's capacity to monitor polymerization and cure kinetics offers nondestructive, real-time process control. A review of the literature illustrates LFR's versatility in studying polymer blends, block copolymers, and complex multicomponent systems. Despite its growing adoption, challenges remain in interpreting LFR spectra due to the complexity of vibrational modes in both disordered and semicrystalline polymers. Looking ahead, combining LFR with advanced computational modeling and in situ measurement capabilities holds promise for deeper insights into polymer behavior, enabling novel applications in both academic and industrial settings.