US 12,257,736 B2
Thermochromic composite material, its preparation and use
Chi Yan Tso, Kowloon (HK); Sai Liu, Kowloon (HK); Hau Him Lee, Kowloon (HK); and Tsz Chung Ho, Kowloon (HK)
Assigned to City University of Hong Kong, Kowloon (HK)
Filed by City University of Hong Kong, Kowloon (HK)
Filed on Feb. 1, 2022, as Appl. No. 17/589,928.
Claims priority of provisional application 63/144,497, filed on Feb. 2, 2021.
Prior Publication US 2022/0242004 A1, Aug. 4, 2022
Int. Cl. B27K 3/15 (2006.01); B27K 3/08 (2006.01); C08L 97/02 (2006.01); C08L 101/14 (2006.01)
CPC B27K 3/153 (2013.01) [B27K 3/08 (2013.01); C08L 97/02 (2013.01); C08L 101/14 (2013.01)] 16 Claims
 
1. A composite material for use in a window unit comprising:
a substrate body having a mesoporous structure of delignified wood defined by a network of interconnected fibers; and
a thermochromic material comprising a hydrogel complex filling and being supported by the mesoporous structure, the hydrogel complex comprising a refractive index-matching polymer including poly(acrylamide) (PAM), the refractive index-matching polymer forming a first crosslinked network holding a plurality of microgel particles of a thermoresponsive hydrogel including poly(N-isopropylacrylamide) (PNIPAM);
wherein the plurality of microgel particles of the thermoresponsive hydrogel undergo a phase transition in direct response to an external temperature exceeding or falling below a critical transition temperature of the thermochromic material, thereby changing an overall transparency of the composite material; and
wherein the critical transition temperature (Tc) of the thermochromic material is from about 20° C. to about 25° C.