Abstract

Inter- and intramolecular hydrogen bonding and their temperature-dependent changes in a poly(4-vinylphenol)/poly(methyl methacrylate)(PVPh 30%/PMMA 70%) blend were investigated using near-infrared (NIR) and infrared (IR) spectroscopy. Band assignments of the fundamentals and first overtones of the OH stretching mode of a free OH group and OH groups in C=O···HO and OH···OH (dimer, trimer, and oligomer) hydrogen bonding of PVPh 30%/PMMA 70% were carried out by comparison between its NIR and IR spectra and comparison with NIR and IR spectra of phenol. The comparison of the NIR spectra of the PVPh 30%/PMMA 70% blend (hereafter, we denote it as PVPh30%) with the corresponding IR spectra reveals that to observe bands arising from the free OH and OH···OH dimer, which is a weaker hydrogen bonding, NIR is better while to investigate bands originating from OH groups in the OH···O=C and OH···OH (oligomer) hydrogen bonds, which are stronger hydrogen bonding, IR is better. Thus, a combination of IR and NIR spectroscopy has provided convincing results for the hydrogen bonding of PVPh30%. The relative intensity of the two bands at 7058 and 6921 cm^–1 (I₇₀₅₈/I₆₉₂₁) due to the first overtones of the OH stretching modes of the free OH group and the OH group in the dimer, respectively, increases significantly above 90 °C, which is close to Tg of PVPh. In concomitance with the intensity increase in the relative intensity of the free OH band, the intensity of a band at 1706 cm^–1 due to the C=O stretching mode of the C=O···HO hydrogen bond of PVPh30% decreases above 90°C. These results suggest that above the Tg of PVPh the C=O···HO hydrogen bond is broken gradually and that the free OH increases. Of note is that below Tg the intensities of NIR bands due to the OH first overtones of free OH group and OH groups in the OH···OH dimer gain intensity in parallel with temperature increase, and above Tg the intensity of the band derived from the OH···OH group increases linearly much slower than that of the band due to the free OH. Moreover, a band due to an OH···OH oligomer decreases linearly. Hence, it is very likely that the OH···OH oligomers dissociate into free OH groups. Anharmonicity of O–H bonds, which is sensitive to a hydrogen bond, was estimated for the free OH and OH bonds in the C=O···HO and OH···OH (dimer, trimer, and oligomer) hydrogen bonding by comparison between the NIR and IR spectra in the OH stretching band regions.

© 2022 The Author(s)

Investigation of the optothermal properties of a new polymeric blend: polymethyl-methacrylate–poly(ethylene-co-vinylacetate)

U. Bernini, G. Carbonara, M. Malinconico, P. Mormile, P. Russo, and M. G. Volpe
Appl. Opt. 31(27) 5794-5798 (1992)

Enhanced upconversion and near-infrared emissions of co-doped Ho³⁺/Yb³⁺ in TeO₂–ZnO–Na₂CO₃–La₂O₃ tellurite glasses

P. X. Le, Nguyen Minh Ty, Jianbei Qiu, Dacheng Zhou, and Ho Kim Dan
Opt. Mater. Express 9(10) 3998-4008 (2019)

Effect of the morphology on the anisotropic light scattering of polycarbonate (PC)/poly(styrene-co-acrylonitrile) (SAN)(70/30) blend

Xianming Dong, Ying Xiong, Guangshun Chen, and Shaoyun Guo
Appl. Opt. 54(4) 608-614 (2015)

Temperature sensing using CdSe quantum dot doped poly(methyl methacrylate) microfiber

Ninik Irawati, Sulaiman W. Harun, Husna A. Rahman, Su Sin Chong, Nur Aliya Hamizi, and Harith Ahmad
Appl. Opt. 56(16) 4675-4679 (2017)

Photochemistry of refractive index structures in poly(methyl methacrylate) by femtosecond laser irradiation

Alexandra Baum, Patricia J. Scully, Maria Basanta, C. L. Paul Thomas, Peter R. Fielden, Nicholas J. Goddard, Walter Perrie, and Paul R. Chalker
Opt. Lett. 32(2) 190-192 (2007)