Design, synthesis, characterization, and aging properties of a new end‐capped three‐dimensional high‐refractive index hybrid organic–inorganic polysiloxane

Abstract

The actual need for hybrid organic-inorganic polysiloxanes is very high due to their importance in optoelectronic applications, especially for the preparation of anti-and low-reflection layers, photopatterned overcoats, flexible hard coats, and glass and metal coatings. However, such three-dimensional hybrid polysiloxanes have very often a limited shelf life and aged very rapidly. Consequently, this type of polymer may require to be stored at cold temperatures and needs to be dilute in organic solvent to a very low solid content, which are unprofitable conditions for commercialization purposes. Therefore, there is an urgent demand to prepare three-dimensional polysiloxanes, which are more resistant toward aging processes. Herein, a new hybrid three-dimensional polysiloxane has been designed and synthesized from three different silane precursors using the sol-gel technology, and characterized using gel permeation chromatography, 1 H, 13 C, and 29 Si nuclear magnetic resonance and MS spectroscopies. One-fourth of the silanol groups present in the polysiloxane have been protected with chlorotrimethylsilane. The refractive index of the silicon wafer coated with the new polysiloxane was found to be 1.53, which is higher compare to traditional values. Importantly, the new protected threedimensional polysiloxane did not age after being stored at T = 40 C for 3 weeks.

New Phenanthrenyl‐Substituted Hybrid Organic‐Inorganic Polysiloxanes for Optoelectronic Applications

“…Importantly the strategy used to synthesize the non‐aging polymers 12 and 13 does not include a protection step of the silanol groups. This is a noteworthy improvement in comparison to our previous report where we used ClSiMe 3 as end‐capping reagent to stabilize the polymers [45] …”

“…For example, imine‐based ligands have been used to generate intrinsic autonomous self‐healable linear polysiloxanes and oligomeric analogues upon metal coordination [42] . In analogy with the alcohol functionality, [43] the protection of the free silanol groups with the silylating agent chlorotrimethylsilane is also a robust tool to improve the resistance of polysiloxanes against aging processes [44,45] . Anti‐aging agents such as benzophenone type‐UV absorbers have been also employed to improve the stabilization of polysiloxanes.…”

“…[42] In analogy with the alcohol functionality, [43] the protection of the free silanol groups with the silylating agent chlorotrimethylsilane is also a robust tool to improve the resistance of polysiloxanes against aging processes. [44,45] Antiaging agents such as benzophenone type-UV absorbers have been also employed to improve the stabilization of polysiloxanes. Keeping polysiloxanes in suitable solvents at very low temperatures is another way to stabilize these polymers without using additional reagents.…”

“…This is a noteworthy improvement in comparison to our previous report where we used ClSiMe 3 as end-capping reagent to stabilize the polymers. [45] Preparation of the films by coating of the polysiloxanes on silicon wafers and glass substrates and their characterization…”