公开(公告)号：US20230212017A1

公开(公告)日：2023-07-06

申请号：US17775415

申请日：2020-11-06

Applicant: EMPA Eidgenoessische Materialpruefungs- und Forschungsanstalt

Inventor： Shanyu ZHAO ,  Gilberto DE FREITAS SIQUEIRA ,  Wim MALFAIT ,  Matthias KOEBEL ,  Christopher UBERT ,  David NORRIS

IPC: C01B33/158 ,  B33Y40/20 ,  B33Y10/00 ,  B33Y70/00 ,  C09D11/322 ,  C09D11/36 ,  C09D11/033 ,  C09D11/037

CPC classification number: C01B33/1585 ,  B33Y40/20 ,  B33Y10/00 ,  B33Y70/00 ,  C09D11/322 ,  C09D11/36 ,  C09D11/033 ,  C09D11/037

Abstract: An ink composition for additive manufacture of silica aerogel objects essentially consists of a gellable silica sol containing an admixture of 30 to 70 vol.% of a mesoporous silica powder in a base solvent. The mesoporous silica powder has a particle size range of 0.001 to 1 mm and a tap density of 30 to 200 kg/m3 and comprises at least 10% by weight of silica aerogel powder. The composition has a yield stress in the range of 30 to 3000 Pa and a viscosity of 5 to 150 Pa·s at a shear rate of 50 s−1. Furthermore, the composition has shear thinning properties defined as a reduction in viscosity by a factor between 10 and 103 for an increase in shear rate by a factor of 104 to 105. A method of additive manufacturing of a three-dimensional silica aerogel object by direct ink writing comprises providing such ink composition, forcing the same through a convergent nozzle, thereby forming a jet of the ink composition which is directed in such manner as to form a three-dimensional object by additive manufacturing. After initiating and carrying out gelation of the gellable silica sol constituting said object, a drying step yields the desired three-dimensional silica aerogel object.

公开(公告)号：US20220089819A1

公开(公告)日：2022-03-24

申请号：US15734657

申请日：2019-06-04

Applicant: EMPA Eidgenoessische Materialpruefungs- und Forschungsanstalt

Inventor： Matthias KOEBEL ,  Ana STOJANOVIC ,  Wim MALFAIT ,  Adilien NOUR

IPC: C08G77/20 ,  C08J9/228

Abstract: A polymeric liquid material formed of molecular building blocks of core-shell type architecture, wherein each building block consists of a hyperbranched polysiloxane core and a functional siloxane shell peripherally attached thereto, the material comprising bridging oxygen moieties (Si—O—Si), hydrolysable alkoxy moieties (Si—O—R) and organofunctional moieties (R′—Si—) and (R1-S1-R2) and less than 0.5 mass percent hydroxy moieties (Si—OH). The core has a degree of polymerization DPcore in the range of 1.3 to 2.7, the shell is formed of R′-substituted siloxane moieties and has a degree of polymerization DPshell in the range of 0.3 to 2.5. At least 75 atomic percent of all Si atoms in the core are bonded exclusively to alkoxy or bridging oxygens, the remainder each being bonded to 3 oxygens and 1 carbon. The total Si to free hydrolysable alkoxy molar ratio in the material is 1:1.25 to 1:2.75, and the material has a viscosity in the range of 10-100,000 cP. A method for preparing the polymeric liquid material relies on first forming the hyper-branched polysiloxane core followed by a build-up of the functional siloxane shell. To do so, a reaction scheme based on adding stoichiometric amounts of acetic anhydride in a water-free environment is exploited.