Fabrication of Mechanically Strong Honeycombs with Aerogel Cores

Abstract

Honeycomb aerogel composites were fabricated by reinforcing selected regions of a native aerogel matrix using photopolymerization. First, alcogels were synthesized by hydrolysis−condensation of a siloxane, and by adding a multifunctional acrylic monomer and a visible-light initiator to the gelation solution. Alcogels were then placed on a programmable translation stage and exposed to a laser. Polymerization and mechanical reinforcement were induced in the exposed regions. After exposure alcogels were dried supercritically. Thermal conductivity and out-of-plane modulus of the resulting honeycombs could be varied between values typical of native aerogels (11 mW/mK and 0.75 MPa) and those of uniformly polymerized composites (65.8 mW/mK and 36.26 MPa) by varying the translation stage speed between 2 and 3 mm/s. The results were interpreted using a rule-of-mixtures model. The mechanical properties of the composites were also investigated using finite element analysis.

Printed aerogels: chemistry, processing, and applications

“…206 The light wavelengths that are used to initiate the photopolymerization are either in the visible green (l = 532 nm), 205,208 or UV (l = 385 or 405 nm) region. 244,266 In the first demonstration of printed aerogels by SLA in 2015, 3D letter-shaped aerogels were fabricated using a template with hollow letters as a mask (Fig. 11a-c).…”

“…The gel can be then exposed to a laser in a hexagonal pattern to completely penetrate the entire gel, initiating photopolymerization reaction to form a polymer. 266 After solvent exchange and supercritical drying, a SiO 2 aerogel composite, composed of an in situ formed honeycomb wall of polymer (which is exposed to the laser) and hexagonal aerogel filler can be obtained (Fig. 11g-i).…”

“…11g-i). 266 Besides molecule-derived SiO 2 aerogels, PmSLA has also been used to print 3D GO and polyethylene glycol diacrylate (PEGDA)/CNF aerogels. 22,244 For the GO aerogels, 244 the authors used GO flakes with photocurable acrylates (bisphenol A ethoxylate dimethacrylate, and PEGDA) and photoinitiator.…”

Nanomaterials in Advanced, High-Performance Aerogel Composites: A Review

“…Although the drying methods were conventional, the laser induced rapid gelation process added the benefit of ease in fabrication by cutting down the time required for gelation. A similar sol modification followed by SLA has realized hybrid constructs with crosslinked hexagonal honeycomb structures and aerogel cores [39]. These modifications of the sol prior to gelation is a common theme in the fabrication of 3D printed aerogels.…”

Ultralight magnetic aerogels from Janus emulsions

“…It is wellknown that honeycomb-like structures are highly desired because they can provide higher mechanical strength and stability, which are relevant for many applications including thermal and acoustic insulation. 42,43 The brown color of the aerogels indicates that MNPs are incorporated into the aerogel, not taken away during the freeze-drying, and oil removal process. Unfortunately, as the size of the MNPs is quite small (13 AE 2 nm), they could not be visualized in the aerogel network by SEM.…”