Kim, Minjae et al. published their research in Advanced Optical Materials in 2021 | CAS: 111-77-3

2-(2-Methoxyethoxy)ethanol (cas: 111-77-3) belongs to ethers. Of all the functional groups, ethers are the least reactive ones. Ether bonds are quite stable towards bases, oxidizing agents and reducing agents. But on the other hand, ethers undergo cleavage by reaction with acids. Autoxidation is the spontaneous oxidation of a compound in air. In the presence of oxygen, ethers slowly autoxidize to form hydroperoxides and dialkyl peroxides. If concentrated or heated, these peroxides may explode. To prevent such explosions, ethers should be obtained in small quantities, kept in tightly sealed containers, and used promptly.SDS of cas: 111-77-3

Natural Hyperbolic Dispersion with Anisotropic Epsilon-Near-Zero and Epsilon-Near-Pole in Squaraine Molecular Film was written by Kim, Minjae;Choi, Kyu Ri;Lee, Yeon Ui;Heinrich, Benoit;Ko, Soo Young;Mathevet, Fabrice;Ribierre, Jean-Charles;D′Aleo, Anthony;Wu, Jeong Weon;Placide, Virginie. And the article was included in Advanced Optical Materials in 2021.SDS of cas: 111-77-3 This article mentions the following:

Epsilon-near-zero (ENZ) optical material has been employed in a number of novel linear and nonlinear optical applications, owing to the vanishing polarization upon an incident optical wave. In a uniaxial medium possessing hyperbolic energy-momentum dispersion of optical wave, ENZ can take place at ordinary and extraordinary permittivities. Organic thin films presenting a lamellar structure have been reported to exhibit a transverse neg. hyperbolic dispersion with ENZ at ordinary permittivity. Here, organic thin film with ENZ at extraordinary permittivity is demonstrated. Newly synthesized polymethine dye (i.e., squaraine indolenine triethyleneglycol mol.) self-organizes to form a layered structure in a pristine film, and both transverse neg. and pos. hyperbolic dispersions are observed at visible wavelengths. Anal. of tens-nanometer-thick pristine film shows that both ENZ and epsilon-near-pole (ENP) occur at longitudinal as well as transverse component of dielec. permittivity. Optical characterization of squaraine pristine film is presented, and the importance of transverse pos. hyperbolic dispersion in such monolithic thin film is discussed. In the experiment, the researchers used many compounds, for example, 2-(2-Methoxyethoxy)ethanol (cas: 111-77-3SDS of cas: 111-77-3).

2-(2-Methoxyethoxy)ethanol (cas: 111-77-3) belongs to ethers. Of all the functional groups, ethers are the least reactive ones. Ether bonds are quite stable towards bases, oxidizing agents and reducing agents. But on the other hand, ethers undergo cleavage by reaction with acids. Autoxidation is the spontaneous oxidation of a compound in air. In the presence of oxygen, ethers slowly autoxidize to form hydroperoxides and dialkyl peroxides. If concentrated or heated, these peroxides may explode. To prevent such explosions, ethers should be obtained in small quantities, kept in tightly sealed containers, and used promptly.SDS of cas: 111-77-3

Referemce:
Ether – Wikipedia,
Ether | (C2H5)2O – PubChem