Reinforcement of silica aerogels using silane-end-capped polyurethanes

Area of Science:

• Materials Science
• Polymer Chemistry

Background:

• Silica aerogels are highly porous materials with unique properties.
• Improving the mechanical strength and durability of silica aerogels is crucial for their applications.
• Polymer reinforcement offers a promising route to enhance aerogel performance.

Purpose of the Study:

• To investigate the use of silane-end-capped urethane prepolymer and chain-extended polyurethane for reinforcing silica aerogels.
• To understand the role of silane end groups in silica network formation and polymer incorporation.
• To evaluate the impact of this reinforcement on the aerogel's morphology, mechanical, and surface properties.

Main Methods:

• One-step sol-gel process using tetraethoxysilane, aminopropyltriethoxysilane (APTES), and APTES-end-capped polyurethanes.
• Solid-state C-13 and Si-29 nuclear magnetic resonance for chemical structure elucidation.
• Characterization of morphology, mechanical properties (compressive modulus), and surface properties.

Main Results:

• Modification with 10 wt% APTES-end-capped chain-extended polyurethane increased compressive modulus by 5-fold.
• The density of the modified aerogels increased by 60%.
• APTES-end-capped chain-extended polyurethane proved effective in enhancing mechanical properties and reducing polarity.

Conclusions:

• Silane-end-capped polyurethanes are effective reinforcements for silica aerogels.
• The incorporation of these polyurethanes leads to significant improvements in mechanical strength and durability.
• This approach offers a method to tailor silica aerogel properties for specific applications.