Cement-based aerogel intelligent light-transmitting material and preparation method thereof

Abstract

The invention provides a cement-based aerogel intelligent light-transmitting material and a preparation method thereof.The cement-based aerogel intelligent light-transmitting material is prepared from a base material and a photosensitive comonomer, the base material is formed by compounding Portland cement and silica sol, the cement accounts for 40-60 wt%, and the silica sol accounts for 40-60 wt%; the photosensitive comonomer comprises a six-membered spiro photosensitive monomer A and a diarylethene derivative monomer B; the use amount of the six-membered spiro photosensitive monomer A is 4-8wt% of the total mass of the matrix material, and the use amount of the diarylethene derivative monomer B is 2-4wt% of the total mass of the matrix material. Through molecular design and an in-situ copolymerization process, a stable photosensitive copolymerization network is constructed in the cement-based aerogel, and dynamic regulation and control and long-term durability of light transmittance are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of aerogel composite materials, and in particular to a cement-based aerogel intelligent light-transmitting material and a preparation method thereof. Background Art

[0002] In recent years, the growing demand for intelligent light-transmitting materials in areas such as building energy conservation, optical devices, and the automotive industry has driven the rapid development of light-responsive materials technology. Photochromic materials, a key branch of this field, can dynamically adjust light transmittance based on changes in external lighting conditions, providing innovative solutions for adaptive shading, privacy protection, and energy management. However, traditional photochromic material systems face significant challenges when combined with cement matrices, limiting their practical application in integrated load-bearing and light-transmitting structures.

[0003] Traditional photochromic technology primarily relies on organic coatings or inorganic composite materials. For example, organic molecules such as spiropyran and diarylethenes are often physically doped into glass or polymer films. Patent CN116835945A discloses a decorative concrete containing a photochromic material and its preparation method, which achieves transmittance changes through light-induced molecular structural transformation. Although such materials have high optical response sensitivity, their inherent defects limit their application in cement-based systems: First, the physically doped organic molecules are prone to migration and precipitation in hot and humid environments, leading to rapid functional degradation; second, the difference in thermal expansion coefficient between the organic coating and the cement matrix can easily cause interfacial delamination; and finally, the highly alkaline environment during cement hydration accelerates the degradation of organic photosensitive molecules, significantly shortening the material's lifespan.

[0004] Aerogel materials, due to their unique nanoporous structure and adjustable optical properties, provide new ideas for the design of intelligent light-transmitting materials. Silica aerogels prepared by the sol-gel process have been shown to achieve a transmittance of up to 90%, but their single function limits their further application. In recent years, researchers have attempted to introduce photosensitive molecules into the aerogel network to give it dynamic response capabilities. CN116023927A discloses a photochromic material, its preparation method and application, in which spiropyran is loaded into the pores of the aerogel by an impregnation method, and its photoisomerization properties are used to achieve transmittance control. However, this type of physical loading method still cannot avoid the problems of molecular migration and agglomeration. In particular, during the recycling process, the photosensitive molecules gradually become inactivated, resulting in a decrease in response efficiency.

[0005] As an emerging composite material, cement-based aerogel combines the mechanical strength of cement with the lightweight and light-transmitting properties of aerogel, showing potential in the field of green buildings. However, existing research on cement-based aerogels has mostly focused on optimizing static properties such as heat insulation and sound insulation, and the exploration of its dynamic optical regulation capabilities is still in its infancy. A few attempts to introduce photochromic functions into cement matrices have mainly adopted surface coating or physical doping methods. CN116639923A discloses a color-changing concrete and a preparation method thereof, in which photochromic microcapsules are dispersed in cement slurry. Although a preliminary light response effect can be achieved, the interface compatibility between the capsules and the matrix is ​​poor, and cracks and shedding are prone to occur after long-term use. In addition, the high alkaline environment of cement poses a severe test to the chemical stability of the photosensitive components. Most organic photosensitive groups will undergo hydrolysis or oxidative decomposition under conditions of pH>10, which seriously shortens the life of the material.

[0006] The core challenges facing current technology are concentrated in three aspects: first, how to achieve efficient chemical bonding between photosensitive molecules and cement-aerogel networks to avoid the inevitable performance degradation caused by physical doping; second, how to maintain the stability of photosensitive groups in a strong alkaline environment to ensure the reliability of the material in long-term outdoor service; third, how to balance the dynamic optical response capability and mechanical properties of the material so that it can achieve rapid transmittance switching (response time <10 seconds) and have sufficient compressive strength (≥4MPa) to support the mechanical loads in actual application scenarios.

[0007] In the existing technology, chemical bonding modification is regarded as a potential path to solve the above problems. By incorporating photosensitive monomers into polymer chains and embedding them into the cement-aerogel network, it is expected to improve molecular stability and interfacial bonding strength. However, the complex chemical environment of cement paste places stringent requirements on copolymerization reaction conditions - for example, conventional free radical polymerization initiators are easily deactivated in alkaline systems, and the reaction efficiency of photosensitive monomers is significantly reduced. In addition, although the porous structure of aerogels is conducive to the penetration and scattering control of light, the spatial confinement effect of nanopores on photosensitive molecules may affect their isomerization efficiency, which needs to be balanced through molecular design and structural optimization.

[0008] To address these challenges, this field urgently needs an innovative material design and preparation method that can construct a stable photosensitive copolymer network in cement-based aerogels, while achieving efficient light response characteristics, excellent weather resistance and reliable mechanical properties, thereby promoting the large-scale application of smart translucent materials in construction, transportation and other fields. Summary of the Invention

[0009] In response to the above technical problems, the present application provides a cement-based aerogel intelligent light-transmitting material and a preparation method thereof. Through molecular design and in-situ copolymerization process, a stable photosensitive copolymer network is constructed in the cement-based aerogel to achieve dynamic regulation of light transmittance and long-term durability.

[0010] A cement-based aerogel intelligent light-transmitting material, the raw materials of which include a matrix material and a photosensitive comonomer, wherein the matrix material is composited by silicate cement and silica sol, wherein the cement accounts for 40-60wt% and serves as a rigid skeleton to provide mechanical support, and ordinary silicate cement with a grade of 42.5 is preferred, whose calcium-silicon ratio (C / S=1.8-2.2) is conducive to forming a stable composite gel with silica sol; the silica sol accounts for 40-60wt% (silicon dioxide content 25-30%, particle size 10-20nm), and a nanoporous network is constructed through a sol-gel reaction, giving the material high light transmittance (initial light transmittance ≥80%) and low density (0.15-0.25g / cm 3 );

[0011] The cement content needs to be ≥40% to maintain a compressive strength of ≥4MPa. However, a higher content (>60%) will reduce porosity and light transmittance. By adjusting the ratio of silica sol to cement, a balance can be achieved between mechanical strength (5-6MPa) and light transmittance (80-85%).

[0012] The photosensitive comonomer includes a six-membered spirocyclic photosensitive monomer A and a diarylethene derivative monomer B;

[0013] The structure of the six-membered spirocyclic photosensitive monomer A is shown in the following formula (1):

[0014]

[0015] Wherein, R represents H or CH3, and n is 5-10;

[0016] The main function of the six-membered spirocyclic photosensitive monomer A is to expand the response band and stability by changing the spirocyclic substituent and connecting chain design. The molecular structure of monomer A consists of a spiropyran ring connected to an acrylate group through a flexible carbon chain. Its photoisomerization property allows the material to switch from an open-ring state (high transmittance) to a closed-ring state (low transmittance) under ultraviolet light.

[0017] The six-membered spirocyclic photosensitive monomer A is used in an amount of 4-8 wt% of the total mass of the matrix material. The content of monomer A is positively correlated with transmittance variation. Below 4 wt% results in insufficient transmittance switching range, while higher amounts (>8 wt%) result in decreased transmittance in the open-ring state due to enhanced light scattering, increasing transmittance fluctuations.

[0018] The structure of the diarylethene derivative monomer B is shown in the following formula (2):

[0019]

[0020] Wherein R represents H or CH3, and m is 5-10.

[0021] Diarylethene derivative monomer B is an acrylate monomer containing a diarylethene group and modified with a siloxane. Its primary function is to optimize light response speed and durability through modification with aromatic ring substituents and functional groups. The siloxane group (-Si(OCH3)3) can bond with cement hydration products through hydrolysis and condensation, improving alkali resistance. The perfluorinated chain also provides increased resistance to acid and alkali corrosion, extending outdoor life.

[0022] The diarylethene derivative monomer B is used in an amount of 2-4 wt% of the total mass of the matrix material. Its two-photon absorption effect can extend the material's light response band to the visible light range (400-550 nm), improving the shielding efficiency in the low-transmittance state. However, if its amount exceeds 4 wt%, it will cause phase separation and deteriorate the uniformity of light transmission.

[0023] A method for preparing a cement-based aerogel intelligent light-transmitting material comprises the following steps: (1) sol preparation: adding silicate cement and silica sol into a reaction vessel, and mechanically stirring at 300 rpm for 10 minutes to form a homogeneous slurry; then sequentially adding a six-membered spirocyclic photosensitive monomer A, a diarylethene derivative monomer B, a photoinitiator and a solvent, and continuing stirring for 20-30 minutes until the system is in a transparent sol state; (2) photopolymerization-gelation: injecting the sol into a mold (thickness 0.5-5 mm), placing it under a dual-band light source of ultraviolet light and visible light to activate the photosensitive comonomer, and performing a gelation reaction, wherein the gelation end point is based on a viscosity of 1000-1500 cP (Brookfield viscometer); (3) drying: immersing the wet gel after gelation in tert-butyl alcohol to replace the solvent, and then performing supercritical CO2 drying to obtain a finished product with a porosity of ≥90% and a pore size of 20-50 nm.

[0024] In step (1), the photoinitiator is a bisacylphosphine oxide, and the amount thereof is 0.5-1.5 wt% of the total weight of the photosensitive monomer. Preferably, the photoinitiator is Irgacure 819, which initiates free radical polymerization under 365 nm ultraviolet light. Excessive use (>1.5 wt%) will cause sudden polymerization, resulting in an uneven gel structure and increased transmittance fluctuation.

[0025] The solvent in step (1) is ethanol, and its amount is 2-5wt% of the mass of the matrix material. The solvent ethanol is only used to dissolve the initiator, and the ethanol is completely volatilized in the subsequent drying process to balance the solubility of the initiator and the cement hydration efficiency.

[0026] The pH value of the entire process of step (1) is adjusted by sodium hydroxide or potassium hydroxide alkaline solution to maintain at 9-10. When the pH is less than 9, the silica sol is easy to flocculate, and when the pH is greater than 10, the side chain of the photosensitive monomer is hydrolyzed.

[0027] In the above step (2), the ultraviolet wavelength is 365nm and the irradiation intensity is 50-80mW / cm2 , visible light wavelength 450nm, irradiation intensity 30-50mW / cm 2 ; Irradiation time is 8-15min; reaction temperature is ≤45℃, and the reaction temperature is controlled at ≤45℃ by water-cooling the mold to prevent thermal pore collapse.

[0028] The specific conditions of supercritical CO2 drying in step (3) above are: temperature 40°C, pressure 10 MPa, and time 4 h.

[0029] The drying conditions in step (3) above are to add 0.5-0.6 wt% cellulose nanocrystals as pore proppant and vacuum dry at 80-85°C for 12-14 hours under normal pressure. When drying under normal pressure, the porosity is reduced to 80-85%.

[0030] Compared with the prior art, this application has the following advantages:

[0031] (1) Dynamic control of light transmittance and synergistic optimization of long-term durability through molecular design;

[0032] (2) Chemical bonding of photosensitive groups: Photosensitive comonomers participate in the copolymerization reaction to form a three-dimensional interpenetrating network of "cement-silica sol-polymer". This design completely avoids the migration of photosensitive molecules caused by physical doping, and the transmittance attenuation is significantly reduced compared to the traditional impregnation method;

[0033] (3) Chemical bonding of photosensitive groups: Photosensitive comonomers participate in the copolymerization reaction to form a three-dimensional interpenetrating network of "cement-silica sol-polymer". This design completely avoids the migration of photosensitive molecules caused by physical doping, and the transmittance attenuation is significantly reduced compared to the traditional impregnation method;

[0034] (4) Alkali-resistant molecular engineering: The siloxane groups in the copolymerized monomers are hydrolyzed in an alkaline environment to form Si-O-Si bonds, forming chemical anchors with the cement hydration product (CSH gel), significantly extending the outdoor service life. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] The specific structures of the raw material photosensitive comonomers used in the various examples and comparative examples of this application can be referred to as shown in Table 1:

[0037] Table 1

[0038] monomer structure A-1 <![CDATA[R=CH3,n=6]]> A-2 R=H,n=5 A-3 <![CDATA[R=CH3,n=9]]> A-4 R=H,n=7 A-5 R=CH3,n=8 B-1 <![CDATA[R=CH3,m=6]]> B-2 R=H,m=6 B-3 <![CDATA[R=CH3,m=9]]> B-4 R=H,m=9 B-5 <![CDATA[R=CH3,m=8]]>

[0039] Example 1

[0040] In a 500 mL three-necked flask, 80 g (40 wt%) of Portland cement (grade 42.5) and 120 g (60 wt%) of silica sol (25% SiO2, particle size 10 nm) were added and mechanical stirring (300 rpm) was initiated for 10 minutes to form a homogeneous slurry. Subsequently, 8 g (4 wt% of the total matrix mass) of photosensitive monomer A1, 4 g (2 wt% of the total matrix mass) of monomer B1, 0.12 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 6 g (3 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.0. The sol was injected into a mold (2 mm thickness) and placed under a dual-band light source (UV 365 nm, 60 mW / cm 2 ; Visible light 450nm, 40mW / cm 2 ) for 10 minutes and then water-cooled to 40°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 92%, a transmittance of 85%, and a compressive strength of 4.8 MPa.

[0041] Example 2

[0042] In a 500 mL three-necked flask, 100 g (50 wt%) of Portland cement (No. 42.5) and 100 g (50 wt%) of silica sol (30% SiO2, particle size 15 nm) were added and mechanical stirring (300 rpm) was started for 10 minutes to form a homogeneous slurry. Subsequently, 12 g (6 wt% of the total matrix mass) of photosensitive monomer A2, 6 g (3 wt% of the total matrix mass) of monomer B2, 0.18 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 10 g (5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.5. The sol was injected into a mold (3 mm thickness) and placed under a dual-band light source (UV 365 nm, 70 mW / cm 2 ; Visible light 450nm, 50mW / cm 2 ) for 12 minutes and then water-cooled to 42°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours, dried at normal pressure with 0.5% cellulose nanofibers, and vacuum-dried at 80°C for 12 hours, yielding a finished product with a porosity of 83%, a transmittance of 82%, and a compressive strength of 5.1 MPa.

[0043] Example 3

[0044] In a 500 mL three-necked flask, 120 g (60 wt%) of Portland cement (grade 42.5) and 80 g (40 wt%) of silica sol (30% SiO2, 20 nm particle size) were added. Mechanical stirring (300 rpm) was initiated for 10 minutes to form a homogeneous slurry. Subsequently, 16 g (8 wt% of the total matrix mass) of photosensitive monomer A3, 8 g (4 wt% of the total matrix mass) of monomer B3, 0.24 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 8 g (4 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 10.0. The sol was injected into a mold (5 mm thickness) and placed under a dual-band light source (UV 365 nm, 80 mW / cm 2 ; Visible light 450nm, 50mW / cm 2 ) for 15 minutes and then water-cooled to 45°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 89%, a transmittance of 84%, and a compressive strength of 6.0 MPa.

[0045] Example 4

[0046] In a 500 mL three-necked flask, 90 g (45 wt%) of Portland cement (grade 42.5) and 110 g (55 wt%) of silica sol (25% SiO2, 10 nm particle size) were added. Mechanical stirring (300 rpm) was initiated for 10 minutes to form a homogeneous slurry. Subsequently, 10 g (5 wt% of the total matrix mass) of photosensitive monomer A4, 5 g (2.5 wt% of the total matrix mass) of monomer B4, 0.12 g (0.8 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 8 g (4 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.2. The sol was injected into a mold (1 mm thickness) and placed under a dual-band light source (UV 365 nm, 55 mW / cm 2 ; Visible light 450nm, 35mW / cm 2 ) for 8 minutes and then water-cooled to 38°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 88%, a transmittance of 83%, and a compressive strength of 5.3 MPa.

[0047] Example 5

[0048] In a 500 mL three-necked flask, 110 g (55 wt%) of Portland cement (grade 42.5) and 90 g (45 wt%) of silica sol (30% SiO2, particle size 15 nm) were added and mechanical stirring (300 rpm) was initiated for 10 minutes to form a homogeneous slurry. Subsequently, 14 g (7 wt% of the total matrix mass) of photosensitive monomer A5, 7 g (3.5 wt% of the total matrix mass) of monomer B5, 0.21 g (1.2 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 9 g (4.5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.8. The sol was injected into a mold (4 mm thickness) and placed under a dual-band light source (UV 365 nm, 75 mW / cm 2 ; Visible light 450nm, 45mW / cm 2 ) for 14 minutes and then water-cooled to 43°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours, dried at atmospheric pressure with 0.5% cellulose nanofibers, and vacuum-dried at 80°C for 12 hours, yielding a finished product with a porosity of 84%, a transmittance of 81%, and a compressive strength of 5.7 MPa.

[0049] Example 6

[0050] In a 500 mL three-necked flask, 84 g (42 wt%) of Portland cement (grade 42.5, C / S = 2.0) and 116 g (58 wt%) of silica sol (25% SiO2, particle size 10 nm) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 9 g (4.5 wt% of the total matrix mass) of photosensitive monomer A1, 5.6 g (2.8 wt% of the total matrix mass) of monomer B2, 0.13 g (0.9 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 8 g (4 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.3. The sol was poured into a mold (1.5 mm thickness) and placed under a dual-band light source (UV 365 nm, 65 mW / cm 2 ; Visible light 450nm, 38mW / cm 2 ) for 9 minutes and then water-cooled to 39°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 90%, a transmittance of 84%, and a compressive strength of 5.0 MPa.

[0051] Example 7

[0052] In a 500 mL three-necked flask, 96 g (48 wt%) of Portland cement and 104 g (52 wt%) of silica sol (30% SiO2, 15 nm particle size) were added and mechanical stirring (300 rpm) was initiated for 10 minutes to form a homogeneous slurry. Subsequently, 11 g (5.5 wt% of the total matrix mass) of photosensitive monomer A2, 6.4 g (3.2 wt% of the total matrix mass) of monomer B3, 0.17 g (1.1 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 9 g (4.5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.6. The sol was injected into a mold (2.5 mm thick) and placed under a dual-band light source (UV 365 nm, 68 mW / cm 2 ; Visible light 450nm, 42mW / cm 2 ) for 11 minutes and then water-cooled to 41°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours, dried at atmospheric pressure with 0.5% cellulose nanofibers, and vacuum-dried at 80°C for 12 hours, yielding a finished product with a porosity of 85%, a transmittance of 83%, and a compressive strength of 5.4 MPa.

[0053] Example 8

[0054] In a 500 mL three-necked flask, 116 g (58 wt%) of Portland cement and 84 g (42 wt%) of silica sol (30% SiO2, 20 nm particle size) were added and mechanical stirring (300 rpm) was initiated for 10 minutes to form a homogeneous slurry. Subsequently, 15 g (7.5 wt% of the total matrix mass) of photosensitive monomer A3, 7.6 g (3.8 wt% of the total matrix mass) of monomer B4, 0.18 g (0.7 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 7 g (3.5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.9. The sol was injected into a mold (4 mm thickness) and placed under a dual-band light source (UV 365 nm, 72 mW / cm 2 ; Visible light 450nm, 44mW / cm 2 ) for 13 minutes and then water-cooled to 44°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 87%, a transmittance of 82%, and a compressive strength of 5.9 MPa.

[0055] Example 9

[0056] In a 500 mL three-necked flask, 88 g (44 wt%) of Portland cement and 112 g (56 wt%) of silica sol (25% SiO2, 10 nm particle size) were added and mechanical stirring (300 rpm) was started for 10 minutes to form a homogeneous slurry. Subsequently, 49.6 g (4.8 wt% of the total matrix mass) of photosensitive monomer A, 4.4 g (2.2 wt% of the total matrix mass) of monomer B5, 0.14 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 8 g (4 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.1. The sol was injected into a mold (thickness 0.8 mm) and placed under a dual-band light source (UV 365 nm, 58 mW / cm 2 ; Visible light 450nm, 37mW / cm 2 ) for 7 minutes and then water-cooled to 37°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours. 0.5% cellulose nanofibers were added during atmospheric drying and vacuum dried at 80°C for 12 hours, resulting in a finished product with a porosity of 86%, a transmittance of 85%, and a compressive strength of 5.2 MPa.

[0057] Example 10

[0058] In a 500 mL three-necked flask, 104 g (52 wt%) of Portland cement and 96 g (48 wt%) of silica sol (30% SiO2, 15 nm particle size) were added and mechanical stirring (300 rpm) was initiated for 10 minutes to form a homogeneous slurry. Subsequently, 513 g (6.5 wt% of the total matrix mass) of photosensitive monomer A, 6 g (3.0 wt% of the total matrix mass) of monomer B1, 0.11 g (0.6 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 10 g (5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.7. The sol was injected into a mold (3.5 mm thick) and placed under a dual-band light source (UV 365 nm, 74 mW / cm 2 ; Visible light 450nm, 46mW / cm 2 ) for 14 minutes and then water-cooled to 43°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 88%, a transmittance of 83%, and a compressive strength of 5.6 MPa.

[0059] Example 11

[0060] In a 500 mL three-necked flask, 94 g (47 wt%) of Portland cement and 106 g (53 wt%) of silica sol (25% SiO2, 10 nm particle size) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 10.4 g (5.2 wt% of the total matrix mass) of photosensitive monomer A1, 5.2 g (2.6 wt% of the total matrix mass) of monomer B2, 0.22 g (1.4 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 9 g (4.5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.4. The sol was injected into a mold (1.2 mm thickness) and placed under a dual-band light source (UV 365 nm, 62 mW / cm 2 ; Visible light 450nm, 40mW / cm 2 ) for 8 minutes and then water-cooled to 38°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours, dried at normal pressure with 0.5% cellulose nanofibers, and vacuum-dried at 80°C for 12 hours, yielding a finished product with a porosity of 84%, a transmittance of 84%, and a compressive strength of 5.3 MPa.

[0061] Example 12

[0062] In a 500 mL three-necked flask, 86 g (43 wt%) of Portland cement and 114 g (57 wt%) of silica sol (30% SiO2, 15 nm particle size) were added and mechanical stirring (300 rpm) was initiated for 10 minutes to form a homogeneous slurry. Subsequently, 29.4 g (4.7 wt% of the total matrix mass) of photosensitive monomer A, 6.8 g (3.4 wt% of the total matrix mass) of monomer B3, 0.08 g (0.5 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 7 g (3.5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.8. The sol was injected into a mold (2.8 mm thickness) and placed under a dual-band light source (UV 365 nm, 66 mW / cm 2 ; Visible light 450nm, 43mW / cm 2 ) for 10 minutes and then water-cooled to 40°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 89%, a transmittance of 82%, and a compressive strength of 5.1 MPa.

[0063] Example 13

[0064] In a 500 mL three-necked flask, 114 g (57 wt%) of Portland cement and 86 g (43 wt%) of silica sol (30% SiO2, 20 nm particle size) were added and mechanical stirring (300 rpm) was initiated for 10 minutes to form a homogeneous slurry. Subsequently, 15.6 g (7.8 wt% of the total matrix mass) of photosensitive monomer A3, 7.2 g (3.6 wt% of the total matrix mass) of monomer B4, 0.34 g (1.5 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 8 g (4 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 10.0. The sol was injected into a mold (4.5 mm thickness) and placed under a dual-band light source (UV 365 nm, 76 mW / cm 2 ; Visible light 450nm, 48mW / cm 2 ) for 15 minutes and then water-cooled to 45°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours, dried at atmospheric pressure with 0.5% cellulose nanofibers, and vacuum-dried at 80°C for 12 hours, yielding a finished product with a porosity of 83%, a transmittance of 81%, and a compressive strength of 5.8 MPa.

[0065] Example 14

[0066] In a 500 mL three-necked flask, 92 g (46 wt%) of Portland cement and 108 g (54 wt%) of silica sol (25% SiO2, particle size 10 nm) were added and mechanical stirring (300 rpm) was started for 10 minutes to form a homogeneous slurry. Subsequently, 10.6 g (5.3 wt% of the total matrix mass) of photosensitive monomer A4, 4.8 g (2.4 wt% of the total matrix mass) of monomer B5, 0.11 g (0.7 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 9 g (4.5 wt% of the total matrix mass) of ethanol were added and stirring was continued for 20 minutes. The pH was adjusted to 9.2. The sol was injected into a mold (thickness 0.7 mm) and placed under a dual-band light source (UV 365 nm, 60 mW / cm 2 ; Visible light 450nm, 39mW / cm 2 ) for 7 minutes and then water-cooled to 37°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 87%, a transmittance of 85%, and a compressive strength of 5.4 MPa.

[0067] Example 15

[0068] In a 500 mL three-necked flask, 108 g (54 wt%) of Portland cement and 92 g (46 wt%) of silica sol (30% SiO2, 15 nm particle size) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 12.4 g (6.2 wt% of the total matrix mass) of photosensitive monomer A5, 6.2 g (3.1 wt% of the total matrix mass) of monomer B1, 0.19 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 10 g (5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.7. The sol was injected into a mold (3.8 mm thickness) and placed under a dual-band light source (UV 365 nm, 72 mW / cm 2 ; Visible light 450nm, 45mW / cm 2 ) for 13 minutes and then water-cooled to 44°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours, dried at atmospheric pressure with 0.5% cellulose nanofibers, and vacuum-dried at 80°C for 12 hours, yielding a finished product with a porosity of 85%, a transmittance of 83%, and a compressive strength of 5.5 MPa.

[0069] Example 16

[0070] In a 500 mL three-necked flask, 82 g (41 wt%) of Portland cement and 118 g (59 wt%) of silica sol (25% SiO2, 10 nm particle size) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 18.4 g (4.2 wt% of the total matrix mass) of photosensitive monomer A, 5.8 g (2.9 wt% of the total matrix mass) of monomer B2, 0.11 g (0.8 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 7 g (3.5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.1. The sol was injected into a mold (1.0 mm thickness) and placed under a dual-band light source (UV 365 nm, 64 mW / cm 2 ; Visible light 450nm, 41mW / cm 2 ) for 8 minutes and then water-cooled to 38°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 90%, a transmittance of 84%, and a compressive strength of 4.9 MPa.

[0071] Comparative Example 1

[0072] In a 500mL three-necked flask, add 120g (60wt%) of Portland cement and 80g (40wt%) of silica sol (30% SiO2). Stir mechanically (300rpm) for 10 minutes to form a homogeneous slurry. Adjust the pH to 9.0. Pour the sol into a mold (2mm thick) and place it under a dual-band light source (UV 365nm, 60mW / cm 2 ; Visible light 450nm, 40mW / cm 2 ) for 10 minutes and then water-cooled to 40°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours) to obtain a finished product with a porosity of 85%, a transmittance of 82% (fixed and unchanged), and a compressive strength of 6.2 MPa.

[0073] Comparative Example 2

[0074] In a 500 mL three-necked flask, 100 g (50 wt%) of Portland cement and 100 g (50 wt%) of silica sol (30% SiO2) were added and mechanical stirring (300 rpm) was started for 10 minutes to form a homogeneous slurry. Subsequently, 4 g (2 wt% of the total matrix mass) of photosensitive monomer A1, 4 g (2 wt% of the total matrix mass) of monomer B1, 0.08 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 8 g (4 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.5. The sol was injected into a mold (thickness 2 mm) and placed under a dual-band light source (UV 365 nm, 60 mW / cm 2 ; Visible light 450nm, 40mW / cm 2 ) for 10 minutes, then water-cooled to 40°C. After gelation, the wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours). The finished product had a transmittance switching range of only 5% (80% → 85%) and a compressive strength of 4.5 MPa.

[0075] Comparative Example 3

[0076] In a 500 mL three-necked flask, 80 g (40 wt%) of Portland cement and 120 g (60 wt%) of silica sol (25% SiO2) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 20 g (10 wt% of the total matrix mass) of photosensitive monomer A2, 6 g (3 wt% of the total matrix mass) of monomer B2, 0.26 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 10 g (5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.0. The sol was injected into a mold (2 mm thickness) and placed under a dual-band light source (UV 365 nm, 60 mW / cm 2; Visible light 450nm, 40mW / cm 2 ) for 10 minutes and then water-cooled at 40°C. The wet gel was replaced with tert-butyl alcohol for 24 hours and then dried with supercritical CO2 (40°C, 10 MPa, 4 hours). The finished product exhibited poor transmittance uniformity (±12%), porosity of 92%, and compressive strength of 3.8 MPa due to phase separation caused by excess monomer A.

[0077] Comparative Example 4

[0078] In a 500 mL three-necked flask, 100 g (50 wt%) of Portland cement and 100 g (50 wt%) of silica sol (30% SiO2) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 8 g (4 wt% of the total matrix mass) of photosensitive monomer A3, 2 g (1 wt% of the total matrix mass) of monomer B3, 0.10 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 8 g (4 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.5. The sol was poured into a mold (2 mm thickness) and irradiated under a dual-band light source for 10 minutes, with water cooling to maintain a temperature of 40°C. The wet gel was replaced with tert-butyl alcohol for 24 h and dried with supercritical CO2 (40 °C, 10 MPa, 4 h) to obtain a finished product with a porosity of 85%, insufficient transmittance switching range (77%→80%), and a compressive strength of 4.6 MPa.

[0079] Comparative Example 5

[0080] In a 500 mL three-necked flask, 120 g (60 wt%) of Portland cement and 80 g (40 wt%) of silica sol (30% SiO2) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 8 g (4 wt% of the total matrix mass) of photosensitive monomer A1, 10 g (5 wt% of the total matrix mass) of monomer B4, 0.18 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 10 g (5 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.5. The sol was poured into a mold (2 mm thickness) and irradiated under a dual-band light source for 10 minutes, with water cooling to maintain a temperature of 40°C. The wet gel was replaced with tert-butanol for 24 hours and dried with supercritical CO2 (40°C, 10 MPa, 4 hours). The finished product had local phase separation due to excessive monomer B, deteriorated transmittance uniformity (difference ±15%), porosity of 89%, and compressive strength of 4.0 MPa.

[0081] Comparative Example 6

[0082] In a 500 mL three-necked flask, 100 g (50 wt%) of Portland cement and 100 g (50 wt%) of silica sol (30% SiO2) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 12 g (6 wt% of the total matrix mass) of photosensitive monomer A2, 6 g (3 wt% of the total matrix mass) of monomer B5, 0.072 g (0.4 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 8 g (4 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.5. The sol was poured into a mold (2 mm thickness) and irradiated under a dual-band light source for 10 minutes, with water cooling to maintain a temperature of 40°C. The wet gel was replaced with tert-butanol for 24 hours and dried with supercritical CO2 (40°C, 10 MPa, 4 hours). The finished product had incomplete polymerization due to insufficient initiator, loose gel structure (porosity 93%), transmittance switching failure (70%→73%), and compressive strength of 3.2 MPa.

[0083] Comparative Example 7

[0084] In a 500 mL three-necked flask, 80 g (40 wt%) of Portland cement and 120 g (60 wt%) of silica sol (25% SiO2) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 16 g (8 wt% of the total matrix mass) of photosensitive monomer A3, 8 g (4 wt% of the total matrix mass) of monomer B1, 0.48 g (2.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 12 g (6 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.5. The sol was poured into a mold (2 mm thickness) and irradiated under a dual-band light source for 10 minutes, with water cooling to maintain a temperature of 40°C. The wet gel was replaced with tert-butanol for 24 hours and dried with supercritical CO2 (40℃, 10MPa, 4 hours). The finished product was subjected to sudden polymerization due to excessive initiator, with uneven pore size distribution (transmittance fluctuation of ±18%, 62%→80%), porosity of 90%, and compressive strength of 3.5MPa.

[0085] Comparative Example 8

[0086] In a 500mL three-necked flask, 80g (40wt%) of Portland cement and 120g (60wt%) of silica sol (25% SiO2) were added and mechanically stirred (300rpm) for 10 minutes to form a homogeneous slurry. The sol was then injected into a mold (2mm thickness). The wet gel was then displaced with tert-butyl alcohol for 24 hours and dried with supercritical CO2 (40°C, 10MPa, 4 hours). Then, 16g (8wt% of the total matrix weight) of photosensitive monomer A3 and 8g (4wt% of the total matrix weight) of monomer B1 were added for impregnation. The finished product exhibited a transmittance switching range of 2% (80% → 82%) and a compressive strength of 4.5MPa.

[0087] Comparative Example 9

[0088] In a 500 mL three-necked flask, 80 g (40 wt%) of Portland cement and 120 g (60 wt%) of silica sol (25% SiO2) were added and mechanically stirred (300 rpm) for 10 minutes to form a homogeneous slurry. Subsequently, 16 g (8 wt% of the total matrix mass) of photosensitive monomer A3, 8 g (4 wt% of the total matrix mass) of monomer B1, 0.24 g (1.0 wt% of the total monomer mass) of photoinitiator Irgacure 819, and 12 g (6 wt% of the total matrix mass) of ethanol were added. Stirring was continued for 20 minutes, and the pH was adjusted to 9.5. The sol was poured into a mold (2 mm thickness) and irradiated under a dual-band light source for 10 minutes with water cooling at 40°C. The wet gel was vacuum dried for 48 hours. The gel was loose, the transmittance uniformity deteriorated (±20% variation), the transmittance switching failed (70% → 72%), and the compressive strength was 3.2 MPa.

[0089] Test example:

[0090] Photoresponse transmittance test

[0091] The test of light response transmittance needs to rely on professional optical instruments and standardized experimental procedures to quantify the dynamic optical properties of the material by simulating the actual lighting environment. The test uses a spectrophotometer equipped with an integrating sphere module (such as PerkinElmer Lambda 950) in conjunction with a dynamic light response test system, where the spectrophotometer is used to measure the transmittance of the material at a specific wavelength, while the dynamic system integrates a dual-band light source (ultraviolet 365nm and visible light 450nm), a temperature control module (accuracy ±0.5℃) and real-time data acquisition software to simulate light switching and record transmittance changes. Before testing, a standard sample (such as 20×20×2mm 3 The uniform gel sheet was stored away from light for 24 hours to eliminate residual stress, and then a baseline calibration was performed: a blank substrate (such as a glass slide) was used to scan the transmittance of the entire 380-780nm band in a spectrophotometer, and the ambient light interference was subtracted. The formal test was divided into two parts: static and dynamic. In the static test, the sample was first placed in a dark room to measure the initial transmittance (such as 85% in Example 1), and then a UV light source (60mW / cm 2) irradiate until the transmittance is stable (usually 5-10 minutes), record the light state transmittance (such as 80%), and the difference between the two is the switching amplitude (ΔT = 5%); the dynamic test is controlled by program to alternately irradiate ultraviolet and visible light (such as ultraviolet irradiation for 30 seconds → visible light reset for 60 seconds as a cycle), run continuously for 50-100 times, and synchronously record the transmittance extreme value and response time of each cycle (such as switching from 80% to 85% requires 25 seconds), while monitoring the ambient temperature and humidity (25°C, 50% RH) to avoid external interference. When processing data, it is necessary to calculate the transmittance switching efficiency (η = ΔT / T0×100%, such as η≈5.9% in Example 1), cycle stability (such as efficiency attenuation ≤5% after 100 times) and uniformity (calculate the local transmittance standard deviation by 5×5 grid scanning, the qualified threshold is ±3%). The test results are shown in Table 2 below:

[0092] Table 2

[0093]

[0094]

[0095] As shown in Table 2, the examples achieve the triple advantages of high switching efficiency (η > 5%), high cyclic stability (> 85%), and high uniformity (σ < 2%) through optimized monomer ratio (A / B synergy), light source parameter matching (UV-visible light balance), and supercritical drying (uniform pores). Defects in the comparative examples, such as monomer overload / underload, initiator failure, and rough drying processes, directly lead to performance degradation. Comparative Example 1 has no monomer A / B, no light responsiveness, and only relies on the inorganic network for light transmission; Comparative Example 2 has insufficient monomer A (2%), and the low degree of cross-linking leads to a sharp drop in efficiency after the cycle and poor uniformity; Comparative Example 3 has an excessive amount of monomer A2 (10%), which causes phase separation, large transmittance fluctuations and a fragile structure; Comparative Example 4 has insufficient monomer B (1%), low shielding efficiency and incomplete switching; Comparative Example 5 has an excessive amount of monomer B (5%), which leads to local phase separation and a huge difference in transmittance; Comparative Example 6 has insufficient initiator and incomplete polymerization, resulting in a loose structure and failure of light transmission; Comparative Example 7 has an excessive amount of initiator, which causes violent polymerization, uneven pore size and drastic transmittance fluctuations.

[0096] The beneficial effects of the cement-based aerogel of the present invention can be seen: ① High-efficiency dynamic light responsiveness: the transmittance switching amplitude (3% to 9%) is significantly higher than that of traditional photochromic materials (usually ≤3%); ② High switching efficiency and stability: the transmittance switching efficiency (η) reaches 5% to 11%, and the efficiency retention rate is 85% to 98% after 100 cycles; ③ Mechanical properties, compressive strength ≥4.8MPa, suitable for the support structure of optical devices.

[0097] The above describes in detail the cement-based aerogel intelligent light-transmitting material and its preparation method of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above examples is intended only to facilitate understanding of the methods and core concepts of the present invention, including the best mode, and to enable anyone skilled in the art to practice the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention, and such improvements and modifications fall within the scope of protection of the claims. The scope of patent protection for the present invention is defined by the claims and may include other embodiments that may be conceived by those skilled in the art. If such other embodiments have structural elements that do not differ from the literal meaning of the claims, or if they include equivalent structural elements that do not differ substantially from the literal meaning of the claims, then such other embodiments are also intended to be included within the scope of the claims. It will be understood by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A cement-based aerogel intelligent light-transmitting material, characterized by: The raw materials of the cement-based aerogel intelligent light-transmitting material include a base material and a photosensitive comonomer. The base material is a composite of silicate cement and silica sol, wherein the cement accounts for 40-60wt% and the silica sol accounts for 40-60wt%. The photosensitive comonomer includes a six-membered spirocyclic photosensitive monomer A and a diarylethene derivative monomer B. The structure of the six-membered spirocyclic photosensitive monomer A is shown in the following formula (1): Wherein, R represents H or CH3, and n is 5-10; The structure of the diarylethene derivative monomer B is shown in the following formula (2): Wherein R represents H or CH3, and m is 5-10.

2. The cement-based aerogel intelligent light-transmitting material according to claim 1, characterized in that: The amount of the six-membered spirocyclic photosensitive monomer A is 4-8 wt % of the total mass of the base material.

3. The cement-based aerogel intelligent light-transmitting material according to claim 1, characterized in that: The amount of the diarylethene derivative monomer B is 2-4 wt % of the total mass of the base material.

4. The method for preparing a cement-based aerogel intelligent light-transmitting material according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) Sol preparation: Add silicate cement and silica sol into a reaction vessel and stir to form a homogeneous slurry; then add the six-membered spirocyclic photosensitive monomer A, diarylethylene derivative monomer B, photoinitiator and solvent in sequence, and continue stirring until the system is in a transparent sol state; (2) Photopolymerization-gelation: Inject the sol into a mold and place it under a dual-band light source of ultraviolet light and visible light to activate the photosensitive copolymer monomer and carry out gelation reaction; (3) Drying: After the gelation is completed, immerse the wet gel in tert-butanol to replace the solvent, and then perform supercritical CO2 drying.

5. The preparation method according to claim 4, characterized in that: In the step (1), the photoinitiator is a bisacylphosphine oxide, and the amount thereof is 0.5-1.5 wt % of the total mass of the photosensitive monomer.

6. The preparation method according to claim 4, characterized in that: The solvent in step (1) is ethanol, and its usage is 2-5 wt% of the mass of the base material.

7. The preparation method according to claim 4, characterized in that: The pH value of the step (1) is maintained at 9-10 throughout the entire process.

8. The preparation method according to claim 4, characterized in that: The ultraviolet wavelength of step (2) is 365nm and the irradiation intensity is 50-80mW / cm 2 , visible light wavelength 450nm, irradiation intensity 30-50mW / cm 2 ; Irradiation time is 8-15min; reaction temperature ≤45℃.

9. The preparation method according to claim 4, characterized in that: The specific conditions of the supercritical CO2 drying in step (3) are: temperature 40°C, pressure 10 MPa, and time 4 hours.

10. The preparation method according to claim 4, characterized in that: The drying conditions in step (3) are as follows: adding 0.5-0.6 wt% of cellulose nanocrystals as pore proppant, and vacuum drying at 80-85° C. for 12-14 h under normal pressure.

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