TY - JOUR
T1 - Raman spectroscopy coupled to computational approaches towards understanding self-assembly in thermoreversible poloxamer gels
AU - Cook, Michael T.
AU - Abou Shamat, Mohamad
AU - Stair, Jacqueline
AU - Calvo-Castro, Jesus
N1 - © 2022 Published by Elsevier B.V. an article which has been published in final form at https://doi.org/10.1016/j.molliq.2022.118660
PY - 2022/2/3
Y1 - 2022/2/3
N2 - The exploitation of vibrational spectroscopy approaches towards the understanding of molecular-level events in polymers, such as poloxamers, is highly warranted. This would facilitate the development of real-time approaches to monitor processes as well as the rational realisation of superior architectures. To date, studies on poloxamer based materials are restricted to low con centration materials and the evaluation of vibrational frequencies involving C-H stretching motions. We carry out an in-depth analysis of thermally-induced micellization processes employing technologically relevant 20% w/w P407 aqueous formulations. Our results, coupling Raman spectroscopy to computational approaches, are unequivocally consistent with such temperature-controlled events not being restricted to molecular re-arrangements involving C-H stretching motions. In fact, the synergistic approach of all key spectral regions was observed to yield optimum delineation of formulations at different temperatures. Vibrational envelopes were deconvoluted and it was observed that vibrational analysis of convoluted spectra can often be misleading. Individual contributions were assigned to either PEO or PPO building blocks by means of quantum-mechanical calculations. Temperature-induced changes to both intensity and vibrational frequencies were statistically evaluated and identified variations rationalised based on intermolecular interactions and structural order/disorder of the polymer units. Such observations were identified to be critically different depending on the nature of the vibrations.
AB - The exploitation of vibrational spectroscopy approaches towards the understanding of molecular-level events in polymers, such as poloxamers, is highly warranted. This would facilitate the development of real-time approaches to monitor processes as well as the rational realisation of superior architectures. To date, studies on poloxamer based materials are restricted to low con centration materials and the evaluation of vibrational frequencies involving C-H stretching motions. We carry out an in-depth analysis of thermally-induced micellization processes employing technologically relevant 20% w/w P407 aqueous formulations. Our results, coupling Raman spectroscopy to computational approaches, are unequivocally consistent with such temperature-controlled events not being restricted to molecular re-arrangements involving C-H stretching motions. In fact, the synergistic approach of all key spectral regions was observed to yield optimum delineation of formulations at different temperatures. Vibrational envelopes were deconvoluted and it was observed that vibrational analysis of convoluted spectra can often be misleading. Individual contributions were assigned to either PEO or PPO building blocks by means of quantum-mechanical calculations. Temperature-induced changes to both intensity and vibrational frequencies were statistically evaluated and identified variations rationalised based on intermolecular interactions and structural order/disorder of the polymer units. Such observations were identified to be critically different depending on the nature of the vibrations.
U2 - 10.1016/j.molliq.2022.118660
DO - 10.1016/j.molliq.2022.118660
M3 - Article
SN - 0167-7322
JO - Journal of Molecular Liquids
JF - Journal of Molecular Liquids
M1 - 118660
ER -