Water-permeable and air-permeable sponge and preparation method thereof

Abstract

The application belongs to the field of high polymer materials, and provides a water-permeable and air-permeable sponge and a preparation method thereof. The application adopts a synergistic design of a crosslinked polydimethylsiloxane continuous phase and a directional through-hole network, forms a through-hole network with an open hole rate of 85-92% and an orientation index not less than 0.60 through directional soluble particle template dissolution, and introduces cellulose nanocrystals with a mass fraction of 0.50-2.00% modified by silane coupling to enhance the network, and covalently fixes 0.10-1.00 wt% of hydrophilic functional silane to realize surface hydrophilic modification, realizes air permeability not less than 400 L·m⁻²·s⁻¹, a pore size gradient of 150-250 μm on the near-skin side to 400-600 μm on the far-skin side, and double-medium high-flux water-permeable and air-permeable performance, solves the coupling contradiction problem between high open hole rate and mechanical bearing rebound attenuation, directional through-hole network cycle stability, and double-medium high-flux and low VOC, and has wide application value in the fields of nursing and sports underwear, masks, briefs, eye masks, shoes and mattresses.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a water-permeable and air-permeable sponge and its preparation method. Background Technology

[0002] With the increasing application of ergonomic design principles in textiles and personal protective equipment, intimate apparel such as nursing and sports bras, masks, underwear, and goggles places stringent comprehensive performance requirements on support materials. These products require prolonged contact with the skin, and their use involves complex conditions such as sweating during exercise, breast milk production, and high-temperature, high-humidity environments. Therefore, support materials must not only possess excellent mechanical load-bearing and resilience to provide effective support and comfort, but also achieve high permeability and breathability to ensure rapid wicking away of sweat and other liquids and free airflow, preventing stuffiness, discomfort, and microbial growth. While traditional silicone rubber foam materials possess good elasticity and biocompatibility, their inherent hydrophobicity leads to liquid retention, and their low breathability causes heat and moisture buildup, making it difficult to meet the comfort requirements of prolonged wear. Developing novel silicone rubber foam materials that combine high permeability and breathability, excellent mechanical properties, and low VOC emissions is of great significance for improving the wearing experience of intimate apparel textiles and expanding the application scope of silicone rubber materials in the fields of personal protection and health. Optimizing the performance of such materials is not only related to the market competitiveness of products, but also directly affects the health and comfort of users, thus becoming a research hotspot in the fields of materials science and textile engineering.

[0003] Currently, the development of permeable and breathable silicone rubber sponges faces multiple technical bottlenecks and inherent contradictions. On the one hand, while increasing the open-cell ratio can significantly improve air permeability, a high open-cell ratio weakens the continuity of the silicone rubber network. This leads to pore wall collapse, increased permanent deformation, and reduced load-bearing capacity during repeated compression-rebound cycles, highlighting the coupling contradiction between mechanical properties and air permeability. On the other hand, the inherent hydrophobicity of silicone rubber makes it difficult for high-open-cell structures to achieve rapid water permeability. Traditional surface hydrophilic modification methods, such as plasma treatment and surface coating, suffer from poor durability of the modified layer and weak adhesion to the matrix. These modified layers are prone to detachment and failure under water washing and mechanical friction, failing to meet long-term use requirements. For example, Chinese patent CN112940335A discloses a method for preparing porous silicone rubber materials, but its random foaming method results in disordered pore orientation, a wide pore size distribution, and a highly tortuous air permeability path, making directional high-throughput transport impossible and failing to solve the problem of hydrophilic modification durability. Furthermore, to enhance the mechanical properties of high-open-porosity silicone rubber networks, researchers attempted to introduce nano-reinforcing fillers. However, the addition of rigid nanoparticles significantly increased the viscosity of the rubber compound, making it difficult to fully penetrate into the pre-formed porous template during low-pressure impregnation processes. This resulted in uneven filling, increased pore structure defects, and ultimately deteriorated material properties. Simultaneously, the insufficient interfacial compatibility between the nanofillers and the silicone rubber matrix easily led to stress concentration points at the interface, reducing the material's fatigue resistance. More critically, how to achieve synergistic optimization of hydrophilic modification, nano-reinforcement, and low-viscosity processing windows while ensuring high open-porosity and pore size gradient structures, and constructing a directional through-pore network to ensure high-flux transport of dual media while meeting the low VOC release and biosafety requirements of Class A textile standards, remains a core challenge that urgently needs to be overcome in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a water-permeable and air-permeable sponge and its preparation method, thereby resolving the coupling contradiction between high porosity and mechanical load rebound attenuation, cyclic stability of directional through-hole network and high flux and low VOC of dual-medium water-permeable and air-permeable silicone rubber sponges.

[0005] This invention employs a synergistic design approach combining a cross-linked polydimethylsiloxane continuous phase with a directional through-pore network. It utilizes directional soluble particle template technology to construct a through-pore structure with pore size gradient and orientation control. Simultaneously, silane-coupled modified cellulose nanocrystals are introduced as a flexible nano-reinforcing phase. Furthermore, the chemical covalent fixation of hydrophilic functional silanes with the silicone rubber network achieves durable hydrophilic modification of both the surface and bulk phases. This results in a significant improvement in mechanical load-bearing capacity and resilience under high porosity conditions, ensures the cyclic stability of the directional through-pore network, enables high-throughput rapid transport in both air and liquid media, and achieves synergistic optimization of low contact angle hydrophilicity and low VOC release. This breakthrough overcomes the bottlenecks in the balance between water permeability, air permeability, and mechanical properties inherent in traditional silicone rubber sponges.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a water-permeable and air-permeable sponge, comprising a cross-linked polydimethylsiloxane continuous phase and a through-pore network, and including the following features:

[0007] a. The through-hole is formed by dissolving oriented soluble particle template, with an opening rate of 85-92%, an orientation index of not less than 0.60, a thickness of 2-8 mm, and a pore size gradient of 150-250 μm on the near-skin side and 400-600 μm on the far-skin side.

[0008] b. The continuous phase is a silicone rubber network formed by crosslinking vinyl-terminated polydimethylsiloxane with a hydrosiloxane, wherein the hydrosiloxane is dimethylmethylhydrosiloxane or a methylhydrosiloxane-dimethylsiloxane copolymer; the crosslinking is a platinum-catalyzed hydrosilylation reaction;

[0009] c. The sponge contains silane-coupled modified cellulose nanocrystals, with a mass fraction of 0.50-2.00%;

[0010] d. The surface or bulk phase of the sponge contains a covalently fixed layer of a hydrophilic functional silane, wherein the hydrophilic functional silane is selected from 3-aminopropyltriethoxysilane and / or 3-glycidoxypropyltrimethoxysilane, and its total mass fraction in the finished sponge is 0.10–1.00%;

[0011] e. The air permeability of the sponge, as determined by GB / T 5453-1997 at a pressure difference of 100 Pa, shall be not less than 400 L·m⁻²·s⁻¹.

[0012] Furthermore, the silane-coupled modified cellulose nanocrystals are prepared according to the following steps:

[0013] A1. Raw materials: 100 parts by weight of microcrystalline cellulose, 60-65% by weight of sulfuric acid, sodium hydroxide, and deionized water;

[0014] A2. Acid hydrolysis: At 40-50℃, treat with sulfuric acid of 60-65% by mass at a mass ratio of acid solution to microcrystalline cellulose of 8:1-12:1 for 30-90 minutes to obtain cellulose nanocrystal dispersion;

[0015] A3. Neutralization and washing: Neutralize with sodium hydroxide solution to pH 6.0-8.0, then wash repeatedly with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 2-5%;

[0016] A4. Coupling: Adjust the pH of the dispersion to 4.5–5.5, add 3-(methacryloyloxy)propyltrimethoxysilane or 3-glycidoxypropyltrimethoxysilane (silane to cellulose nanocrystal mass ratio 2–10%) at 25–35°C, stir for 1–3 hours to promote alkoxy hydrolysis-condensation / ring-opening reaction, then wash and dry to obtain the silane-coupled modified cellulose nanocrystal powder.

[0017] Furthermore, the oriented soluble particle template is prepared according to the following steps:

[0018] C1. Raw material: Sodium chloride or sucrose;

[0019] C2. Grading: Prepare two grades of particles, one with an average particle size of 150-250 μm and the other with an average particle size of 400-600 μm;

[0020] C3. Oriented laying and pre-compression: Small-diameter layer and large-diameter layer are laid in sequence from near skin side to far skin side. The mass ratio of particles near skin side to far skin side is 1.0-2.0. The whole is unidirectionally pre-compressed at 5-20MPa to form a 2-8mm thick oriented soluble particle template. The unidirectional pre-compression direction of the template is parallel to the orientation direction of the long axis of the through hole.

[0021] Furthermore, the covalent fixation of the hydrophilic functional silane is achieved by mixing 0.10–1.00 wt.% of 3-aminopropyltriethoxysilane and / or 3-glycidoxypropyltrimethoxysilane into the composite adhesive, and fixing it during the curing process through alkoxy hydrolysis-condensation and condensation with silanol on the pore wall / cellulose nanocrystal surface.

[0022] Furthermore, the thickness of the proximal lateral lamina accounts for 30-60% of the total thickness, with an average pore size of 150-250 μm, while the average pore size of the distal lateral lamina is 400-600 μm.

[0023] Furthermore, the mass ratio of hydrophilic functional silane to silane-coupled modified cellulose nanocrystals is 0.20-1.00.

[0024] As a concept of this invention, the design of a cross-linked polydimethylsiloxane continuous phase and a directional through-pore network is mainly used to achieve synergistic optimization of water permeability, air permeability, mechanical load-bearing capacity, and hydrophilic wetting properties. Directional soluble particle template technology, through controlling particle size classification and directional laying, forms a through-pore network with a pore size gradient and a high orientation index after dissolution. The pore size gradient design allows the small-pore layer near the skin to achieve a soft fit and rapid liquid absorption, while the large-pore layer on the distal skin provides high-fluidity airflow and rapid liquid drainage channels. Orientation control ensures that the pores are continuous along the thickness direction, significantly reducing the tortuosity of the air and water permeability paths. Vinyl-terminated polydimethylsiloxane and dimethylmethylhydrosiloxane form a three-dimensional silicone rubber network through a platinum-catalyzed addition cross-linking reaction. This network endows the material with excellent elastic recovery and fatigue resistance, maintaining sufficient mechanical strength even under high porosity conditions. Silane-coupled modified cellulose nanocrystals serve as flexible nano-reinforcing phases. The silane coupling layer on their surface forms chemical bonds with the silicone rubber matrix, significantly improving interfacial bonding strength. The high aspect ratio and nanoscale dispersion of the cellulose nanocrystals effectively enhance the network's modulus and tear resistance without significantly increasing the rubber's viscosity. Hydrophilic functional silanes achieve persistent hydrophilic modification of both the surface and bulk phases through covalent fixation with the silicone rubber network, imparting low contact angle properties to the sponge, promoting rapid liquid spreading and transport, and solving the liquid retention problem caused by the inherent hydrophobicity of silicone rubber.

[0025] This invention also discloses a method for preparing a water-permeable and air-permeable sponge, comprising the following steps:

[0026] S1. Preparation of oriented soluble particle template;

[0027] S2. Preparation of composite adhesive: 100 parts by weight of vinyl-terminated polydimethylsiloxane; hydrogen-containing siloxane crosslinking agent added according to Si–H / C=C equivalent ratio of 0.80–1.20; 0.50–2.00 parts by weight of silane-coupled modified cellulose nanocrystals; 0.10–1.00 parts by weight of hydrophilic functional silane; 5–50 ppm of platinum complex catalyst based on platinum content, the platinum complex catalyst being platinum(0)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane; after mixing, degas under low pressure.

[0028] S3. The composite adhesive is impregnated into the oriented soluble particle template under a low pressure environment of 10-50 kPa until it is completely filled;

[0029] S4. Curing at 80-120℃ for 0.50-2.00 hours yields the composite template.

[0030] S5. Dissolve the oriented soluble particle template with deionized water and dry it to obtain a water-permeable and air-permeable sponge.

[0031] Furthermore, the impregnation time for S3 is 10-20 minutes.

[0032] Furthermore, the soluble particle template dissolution process employs multi-stage countercurrent cleaning, with the cleaning liquid volume being 10-30 times the template volume.

[0033] This invention also discloses the application of water-permeable and breathable sponges in nursing and sports bras, masks, underwear and goggles for water permeability, breathability and support and rebound.

[0034] Furthermore, when using water-permeable and breathable sponge as a bra cup pad, the thickness of a single piece is 2-6mm, and the edge thickness gradient ratio is 1.5-3.0.

[0035] Furthermore, the formaldehyde content of the permeable and breathable sponge was ≤20 mg / kg according to GB / T 2912.1-2009; no decomposable carcinogenic aromatic amine dyes were detected according to GB / T17592-2024 (method detection limit 5 mg / kg); the pH of the extract was 4.0–7.5 according to GB / T 7573-2009; and it was odorless according to GB 18401-2010, meeting the Class A requirements of GB 18401-2010.

[0036] Color fastness to water (GB / T 5713-2013) ≥ 4; color fastness to perspiration (acid and alkali, GB / T 3922-2013) ≥ 4; color fastness to dry rubbing (GB / T 3920-2008) ≥ 4.

[0037] In this invention, silane-coupled modified cellulose nanocrystals and hydrophilic functional silanes play a complementary and synergistic role in solving the problems of insufficient mechanical strength and hydrophobicity of high-porosity silicone rubber sponges. Cellulose nanocrystals, as flexible nano-reinforcing phases, primarily enhance the modulus, tear strength, and fatigue resistance of silicone rubber networks. Through surface silane coupling modification, the hydroxyl groups on the surface of cellulose nanocrystals react with silane coupling agents to form a chemically bonded layer. When 3-(methacryloyloxy)propyltrimethoxysilane (MPS) is used, its methacryloyl C=C groups can undergo addition with Si–H under platinum catalysis, allowing the cellulose nanocrystals to be chemically anchored to the silicone rubber network via the coupling layer. When 3-glycidoxypropyltrimethoxysilane (GPTMS) is used, it mainly forms bonds through ring-opening / condensation with the hydroxyl groups on the cellulose surface, without participating in Si–H / olefin addition. The interfacial bonding changes from physical adsorption to chemical bonding, significantly improving stress transfer efficiency. The high aspect ratio and nanoscale dispersion of cellulose nanocrystals in the silicone rubber network form physical cross-linking points, effectively dispersing stress during compression-rebound cycles, inhibiting crack propagation, and reducing permanent deformation. Hydrophilic functional silanes focus on improving the surface wettability and water permeability of materials. Their molecular structure contains both alkoxy or silanol groups that can react with the silicone rubber network, as well as hydrophilic amino or epoxy groups. During crosslinking, the reactive groups of the hydrophilic functional silane participate in the construction of the crosslinked network, while the hydrophilic groups spontaneously migrate to the surface of the sponge and the inner surface of the pore walls, forming a hydrophilic interface layer. The synergistic effect of both is manifested in the following ways: while cellulose nanocrystals enhance the mechanical properties of the network, some of the hydroxyl groups remaining on their surface form hydrogen bonds with the amino or epoxy groups of the hydrophilic functional silane, promoting the uniform distribution of the hydrophilic functional silane on the inner surface of the pore walls and enhancing the uniformity of the hydrophilic modified layer; the addition of hydrophilic functional silanes reduces the surface tension of the rubber compound, improves the wettability of the rubber compound to the pores of the oriented template, and, in conjunction with the low-pressure impregnation process, improves the dispersion uniformity of cellulose nanocrystals in the pore structure, avoiding stress concentration caused by agglomeration.

[0038] Beneficial technical effects

[0039] 1. Directional through-hole network enables high-throughput transmission of dual media: The through-hole network constructed through directional soluble particle template technology has a high porosity of 85-92% and an orientation index of not less than 0.60. The pore size gradient design ensures that the pores are connected along the thickness direction, significantly reducing the tortuosity of the air and water permeability path. The air permeability reaches not less than 400 L·m⁻²·s⁻¹, realizing directional and efficient transmission of air and liquid dual media. In breastfeeding and sports scenarios, it can quickly expel sweat and heat, significantly improving wearing comfort.

[0040] 2. Cellulose nanocrystal reinforcement achieves synergy between high porosity and mechanical properties: Silane-coupled modified cellulose nanocrystals serve as flexible nano-reinforcing phases. Their surface silane coupling layer forms chemical bonds with the silicone rubber network, resulting in high interfacial bonding strength. The nanoscale dispersion and high aspect ratio effectively enhance the modulus and tear resistance of the network without significantly increasing the viscosity of the rubber compound. Even under high porosity conditions, it can still maintain excellent mechanical load-bearing capacity and resilience, significantly reduce compression set, and improve cycle stability, thus overcoming the inherent contradiction between high porosity and mechanical properties.

[0041] 3. Covalent fixation hydrophilic modification achieves durable hydrophilic properties: During the curing process, hydrophilic functional silanes undergo alkoxy hydrolysis-condensation and condensation with silanol on the pore wall / cellulose nanocrystal surface to form a covalent hydrophilic layer; if olefin-functional hydrophilic silanes are used, they can be further grafted to the network via Si–H / olefin addition. The hydrophilic groups are distributed on the surface of the sponge and the inner surface of the pore wall, reducing the water contact angle from the inherent >100° of silicone rubber to <30°, achieving rapid wetting and capillary transport. Moreover, the covalent fixation method ensures the durability of hydrophilic properties. After repeated washing and mechanical friction, the hydrophilic properties retain >80%, solving the problem of easy failure of traditional surface modification methods.

[0042] 4. Low-pressure impregnation process achieves uniform filling and structural integrity: The preparation method of low-pressure impregnation combined with directional template dissolution uses negative pressure to drive the composite rubber to fill the template pores, effectively reducing residual air bubbles, promoting complete wetting of the template pores by the rubber, resulting in high impregnation uniformity, fewer pore structure defects, good continuity of the cured silicone rubber network, and uniform pore wall thickness, ensuring the mechanical consistency of the sponge and the stability of its air and water permeability.

[0043] 5. Low VOC and biosafety meet Class A textile standards: The silicone rubber system and cellulose nanocrystals used in this invention are both low VOC release materials. The platinum-catalyzed addition crosslinking reaction produces no byproducts. Multi-stage countercurrent cleaning ensures the complete removal of soluble template residues. The final product has a formaldehyde content ≤20 mg / kg, no detectable decomposable carcinogenic aromatic amine dyes, an extract pH of 4.0-7.5, no odor, and color fastness to water, perspiration, and dry rubbing is ≥4, meeting the stringent requirements of GB 18401-2010 Class A textile standards. Attached Figure Description

[0044] Figure 1 The effect of porosity on air permeability and compression set.

[0045] Figure 2 The effect of cellulose nanocrystal mass fraction on tensile strength and elongation at break;

[0046] Figure 3The effect of the mass fraction of hydrophilic functional silanes on contact angle and water vapor transmission rate;

[0047] Figure 4 The effect of curing temperature on tensile strength and compressive set;

[0048] Figure 5 This is a pore size distribution diagram of Embodiment 1 of the present invention;

[0049] Figure 6 The FTIR transmission spectrum of the cellulose nanocrystals modified by silane coupling (3-methacryloyloxypropyltrimethoxysilane) of this invention is shown below, along with the unmodified cellulose nanocrystals.

[0050] Figure 7 This is the sponge morphology near the skin side in Embodiment 1 of the present invention;

[0051] Figure 8 This is the morphology of the sponge on the distal skin side of Embodiment 1 of the present invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0053] Example 1

[0054] This embodiment provides a water-permeable and air-permeable sponge, comprising a cross-linked polydimethylsiloxane continuous phase and a through-pore network. The through-pores in this embodiment are formed by the dissolution of oriented soluble particle templates, with an open porosity of 88.5%, a through-pore orientation index of 0.70, a thickness of 5 mm, and a pore size gradient of an average pore size of 200 μm near the skin and 500 μm far from the skin. The continuous phase in this embodiment is a silicone rubber network obtained by cross-linking vinyl-terminated polydimethylsiloxane and dimethylmethylhydrosiloxane, and the cross-linking reaction in this embodiment is promoted by a platinum complex catalyst. The sponge in this embodiment contains silane-coupled modified cellulose nanocrystals, with a mass fraction of 1.25%. The surface or bulk phase of the sponge in this embodiment contains a covalently fixed layer of hydrophilic functionalized silane; the hydrophilic functionalized silane in this embodiment is 3-aminopropyltriethoxysilane, with a total mass fraction of 0.55%. The air permeability of the sponge in this embodiment, as measured according to GB / T 5453-1997 at a pressure difference of 100 Pa, is 450 L·m⁻²·s⁻¹.

[0055] The silane-coupled modified cellulose nanocrystals of this embodiment were prepared according to the following steps: The raw materials were 100 parts by mass of microcrystalline cellulose, 62.5% sulfuric acid, sodium hydroxide, and deionized water. In the acid hydrolysis step, the nanocrystals were treated at 45°C with 62.5% sulfuric acid at a mass ratio of 10:1 (acid to microcrystalline cellulose) for 60 minutes to obtain a cellulose nanocrystal dispersion. In the neutralization and washing step, the nanocrystals were neutralized to pH 7.0 with sodium hydroxide solution and then washed repeatedly with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 3.5%. In the coupling step, 3-methacryloyloxypropyltrimethoxysilane was added to the dispersion of this embodiment. The mass ratio of silane to cellulose nanocrystals in this embodiment was 6%. The mixture was stirred and reacted for 2 hours, followed by washing and drying to obtain the silane-coupled modified cellulose nanocrystal powder of this embodiment.

[0056] The directional soluble particle template of this embodiment is prepared according to the following steps: The raw material is sodium chloride. A grading step prepares two grades of particles, one with an average particle size of 200 μm and the other with an average particle size of 500 μm. In the directional laying and pre-compression step, the small-diameter layer and the large-diameter layer are laid sequentially from the near-skin side to the far-skin side, with a particle mass ratio of 1.5 between the near-skin side and the far-skin side. The entire template is unidirectionally pre-compressed at 12.5 MPa to form a 5 mm thick directional soluble particle template. The unidirectional pre-compression direction of the template is parallel to the long axis orientation direction of the through-hole in this embodiment.

[0057] In this embodiment, the covalent fixation of the hydrophilic functional silane is achieved by incorporating 0.55 wt% of 3-aminopropyltriethoxysilane into a siloxane-alkyl composite prepolymer system, which is then fixed to the pore wall / cellulose nanocrystal surface via alkoxy hydrolysis-condensation during curing. In this embodiment, the near-skin side layer accounts for 50% of the total thickness, with an average pore size of 200 μm, while the far-skin side layer has an average pore size of 500 μm. In this embodiment, the mass ratio of the hydrophilic functional silane to the silane-coupled modified cellulose nanocrystals is 0.44.

[0058] The method for preparing the water-permeable and breathable sponge in this embodiment includes the following steps: S1. Preparing a directional soluble particle template; S2. Formulating a composite adhesive, with 100 parts by weight of vinyl-terminated polydimethylsiloxane, dimethylmethylhydrosiloxane as the hydrogen-containing siloxane crosslinking agent, added according to a Si-H / C=C equivalent ratio of 1.00, 1.25 parts by weight of silane-coupled modified cellulose nanocrystals, 0.55 parts by weight of hydrophilic functional silane, and platinum complex catalyst platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane with a platinum content of 27.5%. S3. The composite adhesive of this embodiment is impregnated into the oriented soluble particle template of this embodiment under a low pressure environment of 30 kPa until it is completely filled, and the impregnation time is 15 minutes; S4. The composite template body is obtained by curing at 100°C for 1.25 hours; S5. The oriented soluble particle template is dissolved with deionized water and dried to obtain a water-permeable and air-permeable sponge. The oriented soluble particle template is dissolved by multi-stage countercurrent cleaning, and the volume of the cleaning liquid is 20 times the volume of the template.

[0059] This embodiment demonstrates the application of a water-permeable and breathable sponge in nursing and sports bras, masks, underwear, goggles, clothing, shoes, and mattresses, providing both water permeability and breathability while offering support and resilience. When used as a bra cup pad, the single-piece thickness of this water-permeable and breathable sponge is 5mm, with an edge thickness gradient ratio of 2.0. According to GB / T 2912.1-2009, the formaldehyde content is 8 mg / kg; according to GB / T 17592-2024, no decomposable carcinogenic aromatic amine dyes were detected; according to GB / T 7573-2009, the pH of the extract is 6.5; and according to GB 18401-2010, it is odorless and meets the Class A requirements of GB 18401-2010. The water fastness is grade 4-5, the perspiration fastness (acid and alkali) is grade 4-5, and the dry rubbing fastness is grade 4-5.

[0060] Features of Example 1: This example uses a moderate parameter configuration, with all parameters selected in the middle range to ensure process stability and product repeatability. An open-cell ratio of 88.5% provides good breathability, and an air permeability of 450 L·m⁻²·s⁻¹ meets high breathability requirements. A moderate cellulose nanocrystal content of 1.25% ensures a balance between mechanical strength and softness, and a cross-linking reaction with a stoichiometric ratio of 1.00 ensures the integrity and uniformity of the network structure. A through-cell orientation index of 0.70 reflects good directional breathability. This example uses sodium chloride as a template material, which has high leaching efficiency and is environmentally friendly. The formaldehyde content is only 8 mg / kg, far below the limit of 20 mg / kg, and the extract pH of 6.5 is within the moderate range of 4.0-7.5. All color fastness properties reach an excellent level of 4-5. The 5mm thickness and 2.0 edge gradient ratio are particularly suitable for use as bra cup padding, providing moderate support while maintaining good breathability and comfort. The process parameter combination in this embodiment is mature and reliable, suitable for industrial mass production, and is particularly suitable for everyday wear such as nursing bras and sports bras that need to be worn for a long time, as well as for applications such as daily protective masks that have high requirements for breathability and comfort.

[0061] Example 2

[0062] This embodiment provides a water-permeable and air-permeable sponge, comprising a cross-linked polydimethylsiloxane continuous phase and a through-pore network. The through-pores in this embodiment are formed by the dissolution of oriented soluble particle templates, with an open porosity of 91%, a through-pore orientation index of 0.75, a thickness of 3 mm, and a pore size gradient of an average pore size of 180 μm near the skin and 550 μm far from the skin. The continuous phase in this embodiment is a silicone rubber network obtained by cross-linking vinyl-terminated polydimethylsiloxane and dimethylmethylhydrosiloxane, and the cross-linking reaction in this embodiment is promoted by a platinum complex catalyst. The sponge in this embodiment contains silane-coupled modified cellulose nanocrystals, with a mass fraction of 0.80%. The surface or bulk phase of the sponge in this embodiment contains a covalently fixed layer of hydrophilic functionalized silane; the hydrophilic functionalized silane in this embodiment is 3-glycidoxypropyltrimethoxysilane, with a total mass fraction of 0.75%. The air permeability of the sponge in this embodiment, as measured according to GB / T 5453-1997 at a pressure difference of 100 Pa, is 520 L·m⁻²·s⁻¹.

[0063] The silane-coupled modified cellulose nanocrystals of this embodiment were prepared according to the following steps: The raw materials were 100 parts by mass of microcrystalline cellulose, 60% by mass of sulfuric acid, sodium hydroxide, and deionized water. In the acid hydrolysis step, the nanocrystals were treated at 42°C with 60% by mass sulfuric acid at a mass ratio of acid to microcrystalline cellulose of 8:1 for 40 minutes to obtain a cellulose nanocrystal dispersion. In the neutralization and washing step, the nanocrystals were neutralized to pH 6.5 with sodium hydroxide solution and then washed repeatedly with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 2.5%. In the coupling step, 3-glycidoxypropyltrimethoxysilane was added to the dispersion of this embodiment. The mass ratio of silane to cellulose nanocrystals in this embodiment was 3%. The mixture was stirred and reacted for 1.2 hours, followed by washing and drying to obtain the silane-coupled modified cellulose nanocrystal powder of this embodiment.

[0064] The directional soluble particle template of this embodiment is prepared according to the following steps: The raw material is sucrose. A grading step prepares two grades of particles, one with an average particle size of 180 μm and the other with an average particle size of 550 μm. In the directional laying and pre-compression step, a small-diameter layer and a large-diameter layer are laid sequentially from the near-skin side to the far-skin side, with a particle mass ratio of 1.8 between the near-skin side and the far-skin side. The entire template is unidirectionally pre-compressed at 8 MPa to form a 3 mm thick directional soluble particle template. The unidirectional pre-compression direction of the template is parallel to the long axis orientation direction of the through-hole in this embodiment.

[0065] In this embodiment, the covalent fixation of the hydrophilic functional silane is achieved by incorporating 0.75 wt% of 3-glycidoxypropyltrimethoxysilane into a siloxane-alkyl composite prepolymer system, which is then fixed to the pore wall / cellulose nanocrystal surface via alkoxy hydrolysis-condensation during curing. In this embodiment, the near-skin side layer accounts for 55% of the total thickness, with an average pore size of 180 μm, while the far-skin side layer has an average pore size of 550 μm. In this embodiment, the mass ratio of the hydrophilic functional silane to the silane-coupled modified cellulose nanocrystals is 0.94.

[0066] The method for preparing the water-permeable and breathable sponge in this embodiment includes the following steps: S1. Preparing a directional soluble particle template; S2. Preparing a composite adhesive, with 100 parts by weight of vinyl-terminated polydimethylsiloxane, dimethylmethylhydrosiloxane as the hydrosiloxane crosslinking agent, added according to a Si-H / C=C equivalent ratio of 0.90, 0.80 parts by weight of silane-coupled modified cellulose nanocrystals, 0.75 parts by weight of hydrophilic functional silane, and platinum complex catalyst platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane as the platinum content, accounting for 10 parts by weight. S3. The composite adhesive of this embodiment is impregnated into the oriented soluble particle template of this embodiment under a low pressure environment of 15 kPa until it is completely filled, and the impregnation time is 12 minutes; S4. The composite template body is obtained by curing at 90°C for 1.50 hours; S5. The oriented soluble particle template is dissolved with deionized water and dried to obtain a water-permeable and air-permeable sponge. The oriented soluble particle template is dissolved by multi-stage countercurrent cleaning, and the volume of the cleaning liquid is 15 times the volume of the template.

[0067] This embodiment demonstrates the application of a water-permeable and breathable sponge in nursing and sports bras, masks, underwear, goggles, clothing, shoes, and mattresses, providing both water permeability and breathability while offering support and resilience. When used as a bra cup pad, the single-piece thickness of this water-permeable and breathable sponge is 3mm, with an edge thickness gradient ratio of 1.8. According to GB / T 2912.1-2009, the formaldehyde content is 5 mg / kg; according to GB / T 17592-2024, no decomposable carcinogenic aromatic amine dyes were detected; according to GB / T 7573-2009, the pH of the extract is 6.0; and according to GB 18401-2010, it is odorless and meets the Class A requirements of GB 18401-2010. The water fastness is grade 4-5, the perspiration fastness (acid and alkali) is grade 5, and the dry rubbing fastness is grade 5.

[0068] Example 2 Features: This example focuses on optimizing high breathability, achieving an open porosity of 91%, close to the upper limit. Combined with a relatively thin 3mm thickness, it achieves excellent breathability and moisture permeability, with an air permeability of 520 L·m⁻²·s⁻¹, the highest among the four examples. A through-pore orientation index of 0.75 demonstrates superior directional breathability. A lower cellulose nanocrystal content of 0.80% and a suitable excess Si-H equivalent ratio of 0.90 result in better softness and skin-friendly comfort. A higher hydrophilic functional silane content of 0.75% significantly improves moisture absorption and wicking capacity, and the mass ratio of hydrophilic silane to cellulose nanocrystals of 0.94, close to the upper limit, enhances surface hydrophilicity. This example uses sucrose as a template material, resulting in a gentler dissolution process, suitable for applications requiring high material purity. A lower pre-compression pressure of 8MPa maintains a relatively loose structure, beneficial for breathability. A lower curing temperature of 90℃ and a suitable extended curing time of 1.50 hours facilitate the formation of a more uniform cross-linked network. The formaldehyde content was the lowest among the four examples, at only 5 mg / kg. The extract pH was 6.0, and the color fastness achieved an excellent level of 4-5 to 5. This example is particularly suitable for applications requiring extreme breathability and rapid moisture wicking, such as high-intensity sports bras, thin summer nursing bras, and sports masks. It is also suitable for products requiring lightweight breathability, such as goggles. The ultra-thin 3mm design and 1.8 edge gradient ratio make it particularly suitable for making seamless bras and lightweight bra cups.

[0069] Example 3

[0070] This embodiment provides a water-permeable and air-permeable sponge, comprising a cross-linked polydimethylsiloxane continuous phase and a through-pore network. The through-pores in this embodiment are formed by the dissolution of oriented soluble particle templates, with an open porosity of 86%, a through-pore orientation index of 0.68, a thickness of 7 mm, and a pore size gradient of an average pore size of 230 μm near the skin and 450 μm distal to the skin. The continuous phase in this embodiment is a silicone rubber network obtained by cross-linking vinyl-terminated polydimethylsiloxane and dimethylmethylhydrosiloxane, and the cross-linking reaction in this embodiment is promoted by a platinum complex catalyst. The sponge in this embodiment contains silane-coupled modified cellulose nanocrystals at a mass fraction of 1.50%. The sponge in this embodiment contains a covalently fixed layer of hydrophilic functional silane on its surface or in its bulk phase. The hydrophilic functional silane in this embodiment is a mixture of 3-aminopropyltriethoxysilane and 3-glycidoxypropyltrimethoxysilane, wherein 3-aminopropyltriethoxysilane accounts for 60% and 3-glycidoxypropyltrimethoxysilane accounts for 40%, with a total mass fraction of 0.35%. The air permeability of the sponge in this embodiment, measured according to GB / T 5453-1997 at a pressure difference of 100 Pa, is 430 L·m⁻²·s⁻¹.

[0071] The silane-coupled modified cellulose nanocrystals of this embodiment were prepared according to the following steps: The raw materials were 100 parts by mass of microcrystalline cellulose, 64% sulfuric acid, sodium hydroxide, and deionized water. In the acid hydrolysis step, the nanocrystals were treated with 64% sulfuric acid at a mass ratio of 10:1 (acid to microcrystalline cellulose) for 80 minutes at 48°C to obtain a cellulose nanocrystal dispersion. In the neutralization and washing step, the nanocrystals were neutralized to pH 7.8 with sodium hydroxide solution and then washed repeatedly with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 4.5%. In the coupling step, 3-methacryloyloxypropyltrimethoxysilane was added to the dispersion of this embodiment. The mass ratio of silane to cellulose nanocrystals in this embodiment was 9%. The mixture was stirred and reacted for 2.8 hours, followed by washing and drying to obtain the silane-coupled modified cellulose nanocrystal powder of this embodiment.

[0072] The directional soluble particle template of this embodiment is prepared according to the following steps: The raw material is sodium chloride. A grading step prepares two grades of particles, one with an average particle size of 230 μm and the other with an average particle size of 450 μm. In the directional laying and pre-compression step, the small-diameter layer and the large-diameter layer are laid sequentially from the near-skin side to the far-skin side, with a particle mass ratio of 1.2 between the near-skin side and the far-skin side. The entire template is unidirectionally pre-compressed at 18 MPa to form a 7 mm thick directional soluble particle template. The unidirectional pre-compression direction of the template is parallel to the long axis orientation direction of the through-hole in this embodiment.

[0073] In this embodiment, the covalent fixation of hydrophilic functional silanes is achieved by incorporating 0.35 wt% of a mixed hydrophilic functional silane into a siloxane-alkyl composite prepolymer system and fixing it to the pore wall / cellulose nanocrystal surface via alkoxy hydrolysis-condensation during curing. The mixture contains 0.21 wt% 3-aminopropyltriethoxysilane and 0.14 wt% 3-glycidoxypropyltrimethoxysilane. In this embodiment, the proximal skin layer accounts for 40% of the total thickness, with an average pore size of 230 μm, while the distal skin layer has an average pore size of 450 μm. The mass ratio of the hydrophilic functional silane to the silane-coupled modified cellulose nanocrystals in this embodiment is 0.23.

[0074] The method for preparing the water-permeable and breathable sponge in this embodiment includes the following steps: S1. Preparing a directional soluble particle template; S2. Preparing a composite adhesive, with 100 parts by weight of vinyl-terminated polydimethylsiloxane, dimethylmethylhydrosiloxane as the hydrosiloxane crosslinking agent, added according to a Si-H / C=C equivalent ratio of 1.10, 1.50 parts by weight of silane-coupled modified cellulose nanocrystals, 0.35 parts by weight of hydrophilic functional silane, and platinum complex catalyst platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane with a platinum content of 45%. S3. The composite adhesive of this embodiment is impregnated into the oriented soluble particle template of this embodiment under a low pressure environment of 45 kPa until it is filled, and the impregnation time is 18 minutes; S4. The composite template body is obtained by curing at 110°C for 0.80 hours; S5. The oriented soluble particle template is dissolved with deionized water and dried to obtain a water-permeable and air-permeable sponge. The oriented soluble particle template is dissolved by multi-stage countercurrent cleaning, and the volume of the cleaning liquid is 28 times the volume of the template.

[0075] This embodiment demonstrates the application of a water-permeable and breathable sponge in nursing and sports underwear, masks, underwear, goggles, clothing, shoes, and mattresses, providing both water permeability and breathability while maintaining support and resilience. In this embodiment, the formaldehyde content was determined to be 12 mg / kg according to GB / T 2912.1-2009; no decomposable carcinogenic aromatic amine dyes were detected according to GB / T 17592-2024; the pH of the extract was 7.0 according to GB / T 7573-2009; and there was no odor according to GB 18401-2010, meeting the Class A requirements of GB 18401-2010. The water fastness is grade 4, the perspiration fastness (acid and alkali) is grade 4, and the dry rubbing fastness is grade 4.

[0076] Example 3 Features: This example focuses on optimizing high strength and structural stability. A low porosity of 86%, combined with a relatively thick 7mm design and a high cellulose nanocrystal content of 1.50%, endows the sponge with excellent mechanical strength, resilience, and structural stability. The air permeability of 430 L·m⁻²·s⁻¹ still meets high air permeability requirements. A through-pore orientation index of 0.68 demonstrates stable directional air permeability. An excess Si-H equivalent ratio of 1.10 ensures sufficient cross-linking to form a dense network structure, enhancing the material's durability and resistance to deformation. A high pre-compression pressure of 18MPa gives the template better density and strength. A high curing temperature of 110℃ and a short curing time of 0.80 hours facilitate rapid molding and improved production efficiency. The combined use of two hydrophilic functional silanes (60% aminopropyl + 40% epoxy) achieves a synergistic effect between the amino hydrophilicity and epoxy reactivity. Although the total amount is low at 0.35%, the mass ratio to the high-content cellulose nanocrystal content (0.23) is still within a reasonable range. The relatively large proximal pore size of 230 μm and the smaller distal pore size of 450 μm form a relatively gentle pore size gradient, which is beneficial to the uniformity of the overall structure. The formaldehyde content is 12 mg / kg, the extract pH is neutral at 7.0, and all color fastness properties reach a good level of 4. This embodiment is particularly suitable for applications requiring strong support, such as large-cup bras, shaping underwear, thick sports protective gear, and impact-resistant masks, where high mechanical strength and resilience are required. It is also suitable for areas requiring good support and washability, such as the crotch area of ​​underwear.

[0077] Example 4

[0078] This embodiment provides a water-permeable and air-permeable sponge, comprising a cross-linked polydimethylsiloxane continuous phase and a through-pore network. The through-pores in this embodiment are formed by the dissolution of oriented soluble particle templates, with an open porosity of 85%, a through-pore orientation index of 0.80, a thickness of 7.5 mm, and a pore size gradient of an average pore size of 155 μm near the skin and 580 μm distal to the skin. The continuous phase in this embodiment is a silicone rubber network obtained by cross-linking vinyl-terminated polydimethylsiloxane and dimethylmethylhydrosiloxane, and the cross-linking reaction in this embodiment is promoted by a platinum complex catalyst. The sponge in this embodiment contains 2.00% by mass of silane-coupled modified cellulose nanocrystals. The sponge in this embodiment contains a covalently fixed layer of hydrophilic functional silane on its surface or in its bulk phase. The hydrophilic functional silane in this embodiment is a mixture of 3-aminopropyltriethoxysilane and 3-glycidoxypropyltrimethoxysilane, wherein 3-aminopropyltriethoxysilane accounts for 70% and 3-glycidoxypropyltrimethoxysilane accounts for 30%, with a total mass fraction of 0.95%. The air permeability of the sponge in this embodiment, measured according to GB / T 5453-1997 at a pressure difference of 100 Pa, is 415 L·m⁻²·s⁻¹.

[0079] The silane-coupled modified cellulose nanocrystals of this embodiment were prepared according to the following steps: The raw materials were 100 parts by mass of microcrystalline cellulose, 65% by mass of sulfuric acid, sodium hydroxide, and deionized water. In the acid hydrolysis step, the nanocrystals were treated at 50°C with 65% by mass sulfuric acid at a mass ratio of acid to microcrystalline cellulose of 12:1 for 90 minutes to obtain a cellulose nanocrystal dispersion. In the neutralization and washing step, the nanocrystals were neutralized to pH 8.0 with sodium hydroxide solution and then washed repeatedly with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 5%. In the coupling step, 3-glycidoxypropyltrimethoxysilane was added to the dispersion of this embodiment. The mass ratio of silane to cellulose nanocrystals in this embodiment was 10%. The mixture was stirred and reacted for 3 hours, followed by washing and drying to obtain the silane-coupled modified cellulose nanocrystal powder of this embodiment.

[0080] The directional soluble particle template of this embodiment is prepared according to the following steps: The raw material is sucrose. A grading step prepares two grades of particles, one with an average particle size of 155 μm and the other with an average particle size of 580 μm. In the directional laying and pre-compression step, a small-diameter layer and a large-diameter layer are laid sequentially from the near-skin side to the far-skin side, with a particle mass ratio of 1.9 between the near-skin side and the far-skin side. The entire template is unidirectionally pre-compressed at 18 MPa to form a 7.5 mm thick directional soluble particle template. The unidirectional pre-compression direction of the template is parallel to the long axis orientation direction of the through-hole in this embodiment.

[0081] In this embodiment, the covalent fixation of hydrophilic functional silanes is achieved by incorporating 0.95 wt% of a mixed hydrophilic functional silane into a siloxane-alkyl composite prepolymer system and fixing it to the pore wall / cellulose nanocrystal surface via alkoxy hydrolysis-condensation during curing. The mixed silane comprises 0.665 wt% 3-aminopropyltriethoxysilane and 0.285 wt% 3-glycidoxypropyltrimethoxysilane. In this embodiment, the proximal skin layer accounts for 58% of the total thickness, with an average pore size of 155 μm, while the distal skin layer has an average pore size of 580 μm. The mass ratio of the hydrophilic functional silane to the silane-coupled modified cellulose nanocrystals in this embodiment is 0.48.

[0082] The method for preparing the water-permeable and breathable sponge in this embodiment includes the following steps: S1. Preparing a directional soluble particle template; S2. Preparing a composite adhesive, with 100 parts by weight of vinyl-terminated polydimethylsiloxane, dimethylmethylhydrosiloxane as the hydrosiloxane crosslinking agent, added according to a Si-H / C=C equivalent ratio of 1.00, 2.00 parts by weight of silane-coupled modified cellulose nanocrystals, 0.95 parts by weight of hydrophilic functional silane, and platinum complex catalyst platinum(O)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane with a platinum content of 48%. S3. The composite adhesive of this embodiment is impregnated into the oriented soluble particle template of this embodiment under a low pressure environment of 45 kPa until it is filled, and the impregnation time is 19 minutes; S4. The composite template body is obtained by curing at 115°C for 1.80 hours; S5. The oriented soluble particle template is dissolved with deionized water and dried to obtain a water-permeable and air-permeable sponge. The oriented soluble particle template is dissolved by multi-stage countercurrent cleaning, and the volume of the cleaning liquid is 28 times the volume of the template.

[0083] This embodiment demonstrates the application of a water-permeable and breathable sponge in nursing and sports underwear, masks, underwear, goggles, clothing, shoes, and mattresses, providing both water permeability and breathability while maintaining support and resilience. In this embodiment, the formaldehyde content was determined to be 15 mg / kg according to GB / T 2912.1-2009; no decomposable carcinogenic aromatic amine dyes were detected according to GB / T 17592-2024; the pH of the extract was 6.8 according to GB / T 7573-2009; and it was odorless according to GB 18401-2010, meeting the Class A requirements of GB 18401-2010. The water fastness is grade 4, the perspiration fastness (acid and alkali) is grade 4, and the dry rubbing fastness is grade 4-5.

[0084] Example 4 Features: This example focuses on verifying the feasibility of the claims' boundaries, employing boundary or near-boundary value configurations for multiple parameters. An open porosity of 85% is the lower boundary actual value (first-level boundary verification), verifying that even under the lowest open porosity condition, an air permeability of 415 L·m⁻²·s⁻¹ can still be maintained, meeting the performance requirement of over 400 L·m⁻²·s⁻¹. A through-pore orientation index of 0.80 is the highest among the four examples, demonstrating optimal directional air permeability. A cellulose nanocrystal content of 2.00% is the upper boundary actual value (first-level boundary verification), proving the processability and performance controllability of the material under high filler content. A hydrophilic functionalized silane content of 0.95% is close to the upper boundary, and the mass ratio of 0.48 is within a reasonable range, demonstrating the feasibility of a high degree of hydrophilic modification. The extremely large pore size gradient design (155 μm near the lower limit on the near-skin side and 580 μm near the upper limit on the far-skin side) resulted in the most significant directional air permeability. Combined with a near-skin side layer thickness of up to 58% and a particle mass ratio of 1.9, this verified the structural stability of the extreme pore size distribution. Multiple cellulose nanocrystal preparation parameters, including a sulfuric acid concentration of 65% (first-level boundary verification), an acid hydrolysis temperature of 50℃ (first-level boundary verification), an acid hydrolysis time of 90 minutes, a neutralization pH of 8.0, a solid content of 5%, a coupling agent mass ratio of 10%, and a reaction time of 3 hours, all reached their upper limits, demonstrating the feasibility of enhanced acid hydrolysis and efficient coupling processes. A stoichiometric ratio of 1.00 ensured sufficient cross-linking of the highly filled system, and a platinum content of 48 ppm, close to the upper limit, guaranteed catalytic efficiency. A curing temperature of 115℃ and a curing time of 1.80 hours, close to the upper limits, verified the feasibility of high-temperature, long-term curing. With a formaldehyde content of 15 mg / kg and an extract pH of 6.8, all color fastness grades reached 4 to 4-5. This embodiment is particularly suitable for special application scenarios that require extreme performance, such as high-end products that require verification of material performance boundaries, such as heavy-duty shaping underwear, professional sports protective gear, medical protective masks, and high-strength support goggles. It fully demonstrates the scientific rationality and industrial feasibility of the solution scope.

[0085] Comparative Example 1

[0086] It is basically the same as Example 1, except that the porosity is 82%, which is achieved by increasing the pre-compression pressure of the oriented soluble particle template to 15 MPa. The amount of other components and the preparation conditions remain unchanged.

[0087] Comparative Example 2

[0088] It is basically the same as Example 1, except that the porosity is 94%, which is achieved by reducing the pre-compression pressure of the oriented soluble particle template to 9 MPa, while the amount of other components and preparation conditions remain unchanged.

[0089] Comparative Example 3

[0090] The method is basically the same as Example 1, except that the through-hole orientation index is 0.50, which is achieved by preparing a soluble particle template using a non-directional laying method, that is, mixing the two grades of particles and laying them randomly, while keeping the amount of other components and preparation conditions unchanged.

[0091] Comparative Example 4

[0092] The process is basically the same as in Example 1, except that the average pore size on the near-skin side is 130 μm. Particles with an average particle size of 130 μm are prepared by sieving to form the near-skin side layer. The amounts of other components and the preparation conditions remain unchanged.

[0093] Comparative Example 5

[0094] The method is basically the same as in Example 1, except that the average pore size of the distal skin side is 650 μm. Particles with an average particle size of 650 μm are prepared by sieving to serve as the distal skin side layer. The amounts of other components and preparation conditions remain unchanged.

[0095] Comparative Example 6

[0096] The method is basically the same as in Example 1, except that the mass fraction of cellulose nanocrystals is 0.35%, and the amount of cellulose nanocrystals added is reduced to 0.35% when preparing the composite adhesive, while the amount of other components and preparation conditions remain unchanged.

[0097] Comparative Example 7

[0098] The method is basically the same as in Example 1, except that the mass fraction of cellulose nanocrystals is 2.30%, and the amount of cellulose nanocrystals added is increased to 2.30% when the composite adhesive is prepared. The amounts of other components and preparation conditions remain unchanged.

[0099] Comparative Example 8

[0100] The process is basically the same as in Example 1, except that the mass fraction of the hydrophilic functional silane is 0.05%, and the amount of 3-aminopropyltriethoxysilane added is reduced to 0.05% when preparing the composite compound. The amounts of other components and the preparation conditions remain unchanged.

[0101] Comparative Example 9

[0102] The process is basically the same as in Example 1, except that the mass fraction of the hydrophilic functional silane is 1.15%, and the amount of 3-aminopropyltriethoxysilane added is increased to 1.15% when the composite compound is prepared. The amounts of other components and the preparation conditions remain unchanged.

[0103] Comparative Example 10

[0104] The process is basically the same as in Example 1, except that silane-coupled modified cellulose nanocrystals are not added, and cellulose nanocrystals are not added when preparing the composite adhesive. The amounts of other components and preparation conditions remain unchanged.

[0105] Comparative Example 11

[0106] The process is basically the same as in Example 1, except that no hydrophilic functional silane is added, and 3-aminopropyltriethoxysilane is not added when preparing the composite adhesive. The amounts of other components and the preparation conditions remain unchanged.

[0107] Comparative Example 12

[0108] The process is basically the same as in Example 1, except that the equivalent ratio of Si-H to C=C is 0.70, and the amount of dimethylmethylhydrosiloxane and polysiloxane added is reduced to make the equivalent ratio 0.70 when the composite compound is formulated. The amount of other components and the preparation conditions remain unchanged.

[0109] Comparative Example 13

[0110] It is basically the same as Example 1, except that the curing temperature is 70°C and it is cured at 70°C for 1.25 hours. The amount of other components and the preparation conditions remain unchanged.

[0111] Performance testing:

[0112] Experiment 1: Air Permeability Test

[0113] The test subject was a water-permeable and air-permeable sponge. The purpose of the test was to evaluate the air permeability of the sponge and verify the air permeability efficiency of the through-pore network. The test principle was based on Darcy's law, measuring the airflow rate per unit area per unit time by applying a fixed pressure difference. The experimental method adopted the GB / T 5453-1997 standard "Determination of Air Permeability of Textile Fabrics". The sample (circular with a diameter of 100 mm) was clamped between the upper and lower clamps of the air permeability tester (YG461E type) and sealed. A pressure difference of 100 Pa was applied, and the steady-state airflow rate Q (L / min) was recorded. The test conditions were a temperature of 20±2℃ and a relative humidity of 65±3%RH. Each sample was tested 5 times and the average value was taken. Key parameters included a pressure difference of 100 Pa and a sample area of ​​78.5 cm². Data processing was performed according to GB / T 5453-1997. Air permeability was calculated under a specified pressure difference (ΔP=100 Pa in this test): AP=Q×60 / A (where Q is L / min and A is m²). The unit of AP is L·m⁻²·s⁻¹, and the criterion is ≥400 L·m⁻²·s⁻¹.

[0114] Experiment 2: Compression Permanent Deformation Test

[0115] The test subject was a water-permeable and breathable foam product. The purpose of the test was to evaluate the sponge's resilience and deformation resistance under long-term compressive load. The test principle was based on the residual deformation rate of the material after being held under constant compressive strain for a certain period of time. The experimental method referred to GB / T 6669-2008 "Determination of Compression Set of Flexible Foam Polymer Materials". The sample (a cylinder with a diameter of 29 mm × the original thickness) was placed between two parallel metal plates, compressed to 50% of the original thickness at 23±2℃ and held for 22 hours. After removing the load, it was allowed to stand at room temperature for 30 minutes to measure the final thickness. The test conditions were temperature 23±2℃ and relative humidity 50±5%RH. Three samples were tested in each group. Key parameters included compression ratio of 50%, holding time of 22 hours, and recovery time of 30 minutes. Data processing was performed by calculating the compression set rate CS=(t0-t2) / (t0-t1)×100%, where t0 is the original thickness, t1 is the compressed thickness, and t2 is the recovered thickness. A deformation rate ≤15% was considered excellent.

[0116] Experiment 3: Tensile Strength and Elongation at Break Test

[0117] The test subject was a water-permeable and breathable sponge product. The purpose of the test was to evaluate the mechanical strength and elongation properties of the sponge. The test principle was based on the stress-strain relationship of the material under constant-rate tensile stress. The experimental method referred to GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber". The specimen was cut into a dumbbell shape (Specimen No. 2, total length 75 mm, narrow width 4 mm), and stretched at 500 mm / min at 23±2℃ until fracture using a universal testing machine (Instron 5966). The maximum tensile stress and elongation at fracture were recorded. The standard was based on GB / T 528-2009. The test conditions were temperature 23±2℃, relative humidity 50±5%RH, and 5 specimens were tested in each group, with the average value taken. Key parameters included tensile rate 500 mm / min and gauge length 25 mm. The data processing yields tensile strength σ = F / A (MPa) and elongation at break ε = (L - L0) / L0 × 100%, where F is the maximum tensile force, A is the original cross-sectional area, L is the fracture length, and L0 is the original gauge length.

[0118] Experiment 4: Moisture-wicking performance test

[0119] The test subject was a water-permeable and air-permeable sponge. The purpose of the test was to evaluate the moisture absorption rate and permeability of the sponge, and to verify the modification effect of hydrophilic functionalized silanes. The test principle was based on the water vapor transmission rate of the material under standard atmospheric pressure. The experimental method referred to GB / T 12704.1-2009 "Textiles - Test Methods for Moisture Permeability - Part 1: Moisture Absorption Method". The sample (70mm diameter circle) was sealed in a permeation cup containing 10g of desiccant (anhydrous calcium chloride). The permeation cup was placed in a constant temperature and humidity chamber at 38±1℃ and 90±2%RH. The sample was weighed every hour for 24 consecutive hours, and a weight gain-time curve was plotted. The standard was based on GB / T 12704.1-2009. The test conditions were 38±1℃ and 90±2%RH. Key parameters included sample area of ​​38.5 cm² and test duration of 24 hours. Data processing calculates the water vapor transmission rate WVT=Δm / (A×t) based on the slope during the steady-state phase, where Δm is the weight gain (g), A is the sample area (m²), and t is the time (h), with units of g·m⁻²·h⁻¹.

[0120] Experiment 5: Contact Angle Test

[0121] The test subject was a water-permeable and air-permeable sponge surface. The purpose of the test was to evaluate the hydrophilicity of the sponge surface and verify the fixation effect of hydrophilic functionalized silanes. The test principle was based on the wetting behavior of droplets on a solid surface, and the surface energy was quantified by measuring the contact angle of the liquid-solid-gas three phases. The experimental method used a video optical contact angle meter (SDC-200S model). The sample was fixed flat on the test stage, and 2 μL of deionized water was dropped onto the sample surface using the pendant drop method. Side view images were captured at 1 second, 5 seconds, 10 seconds, and 30 seconds after the drop was added. The droplet profile was fitted by software and the contact angle was calculated. The test conditions were a temperature of 25±1℃ and a relative humidity of 40±5%RH. Key parameters included the droplet volume of 2 μL and the test time of 1 / 5 / 10 / 30 seconds. Data processing: The average value was taken from 5 different locations for each sample. A contact angle θ < 90° was considered hydrophilic; the smaller the θ, the stronger the hydrophilicity. For samples not explicitly defined in the claims, the hydrophilicity should be significantly reduced compared to the comparative example.

[0122] Experiment 6: Determination of Pore Size Distribution and Aperture Ratio

[0123] The test subject was a water-permeable and air-permeable sponge product. The purpose of the test was to characterize the pore size distribution, average pore size, and open porosity of the sponge, and to verify the interconnected pore network structure. The test principle was based on the mercury intrusion porosimetry to determine the pore size distribution and the Archimedes' displacement method to determine the open porosity. The experimental method used a fully automated mercury intrusion porosimetry instrument (AutoPore V9620 model) to determine the pore size distribution. The sample (approximately 1 cm³) was placed in a dilatometer, vacuumed, and then mercury was injected. The pressure was gradually increased to 400 MPa, and the pressure-mercury intrusion curve was recorded. The pore size distribution was calculated using the Washburn equation d=(-4γcosθ) / P. The open porosity was determined using GB / T 6343-2009 "Determination of Apparent Density of Foamed Plastics and Rubber" combined with the liquid displacement method, measured by ρ... a (apparent density) and ρ s (Skeleton density) Calculation of porosity φ=(1-ρ a / ρ s ()×100%. Test conditions were a temperature of 25±1℃. Key parameters included a mercury contact angle of 130° and a maximum pressure of 400 MPa. Data processing was used to plot pore size distribution curves and calculate the average pore size and porosity near and far from the skin side.

[0124] Experiment 7: Scanning Electron Microscopy Morphology Characterization

[0125] The test subject was the cross-section and surface of a water-permeable and air-permeable sponge. The purpose of the test was to observe the microstructure, interconnected pore structure, cellulose nanocrystal dispersion, and pore wall thickness of the sponge. The test principle was based on secondary electron imaging technology. The experimental method employed a field emission scanning electron microscope (FESEM, ZEISS Sigma 300). The sample was cut along its thickness to obtain the cross-section, and liquid nitrogen embrittlement was used to preserve the original structure. Vacuum gold sputtering (10 nm thickness) was applied to enhance conductivity. Low-magnification (×100), medium-magnification (×500), and high-magnification (×5000) images were captured under accelerating voltage of 5 kV and working distance of 8 mm to observe the interconnected pore network, pore size gradient, cellulose nanocrystal distribution, and silicone rubber matrix morphology. The test conditions were a vacuum of 1×10⁻⁻⁻⁶. 4 Pa. Key parameters included an accelerating voltage of 5 kV and a gold sputtering thickness of 10 nm. Data processing involved using ImageJ software to analyze the high-magnification images and determine the size and distribution uniformity of the cellulose nanocrystals.

[0126] The above four sets of single-factor experiments, by fixing the basic formulation of Example 1 and independently varying four key parameters—open porosity, cellulose nanocrystal mass fraction, hydrophilic functional silane mass fraction, and curing temperature—systematically verified the influence of each parameter on material properties and the rationality of the parameter range in the claims. The experimental design followed the principle of the controlled variable method to ensure the reliability and comparability of the data. Figure 1To investigate the effect of porosity on air permeability and compression set, the following conditions were used: 100 parts by mass of vinyl-terminated polydimethylsiloxane, Si-H to C=C equivalent ratio of 1.00, platinum catalyst of 27.5 ppm, 1.25% silane-coupled modified cellulose nanocrystals, 0.55% hydrophilic functional silane, thickness of 5 mm, near-skin pore diameter of 200 μm, far-skin pore diameter of 500 μm, through-pore orientation index of 0.70, and curing conditions of 100℃ for 1.25 hours. The porosity was adjusted by regulating the pre-compression pressure. Figure 2 To investigate the effect of the mass fraction of cellulose nanocrystals on tensile strength and elongation at break, the following conditions were used: 100 parts by mass of vinyl-terminated polydimethylsiloxane, Si-H to C=C equivalent ratio of 1.00, 27.5 ppm platinum catalyst, 0.55% hydrophilic functional silane, porosity of 88.5%, thickness of 5 mm, near-skin pore diameter of 200 μm, far-skin pore diameter of 500 μm, and curing conditions of 100 °C × 1.25 h. The mass fraction of cellulose nanocrystals was varied. Figure 3 To investigate the effect of the mass fraction of hydrophilic functional silane on the contact angle (30 seconds) and water vapor transmission rate, the following fixed conditions were used: 100 parts by mass of vinyl-terminated polydimethylsiloxane, Si-H to C=C equivalent ratio of 1.00, platinum catalyst of 27.5 ppm, 1.25% silane-coupled modified cellulose nanocrystals, porosity of 88.5%, thickness of 5 mm, near-skin pore size of 200 μm, far-skin pore size of 500 μm, and curing conditions of 100 °C × 1.25 h. The mass fraction of hydrophilic functional silane was varied. Figure 4To investigate the effect of curing temperature on tensile strength and compressive set, the following conditions were used: 100 parts by mass of vinyl-terminated polydimethylsiloxane, Si-H to C=C equivalent ratio of 1.00, 27.5 ppm platinum catalyst, 1.25% silane-coupled modified cellulose nanocrystals, 0.55% hydrophilic functionalized silane, 88.5% porosity, 5 mm thickness, and 1.25 hours of curing time, with varying curing temperature. Single-factor experiments on porosity revealed that the 85-92% range was based on a scientific consideration of balancing air permeability and structural stability. When the porosity was below the lower limit of 85%, the air permeability dropped sharply to 405 L·m⁻²·s⁻¹, failing to meet air permeability requirements. Conversely, when it was above the upper limit of 92%, the compressive set surged to over 16.5%, leading to a loss of long-term stability. The optimal performance within the 88.5-90% range in the experimental data validated the accuracy of the claimed scope. Single-factor experiments on the mass fraction of cellulose nanocrystals, spanning a wide range of 0.30-2.60%, confirmed the necessity of the 0.50-2.00% range. Below the lower limit of 0.50%, the tensile strength was only 0.71 MPa, which could not provide sufficient mechanical support. Above the upper limit of 2.00%, although the strength increased to 1.28 MPa, the elongation at break plummeted to 265%, making the material brittle and losing its flexibility. Furthermore, the marginal effect of strength gain from adding cellulose nanocrystals above 2.30% diminished, while the elongation continued to deteriorate to 210%. This fully demonstrates that the upper limit of 2.00% is the critical point for a comprehensive balance between strength and flexibility. Single-factor experiments using the mass fraction of hydrophilic functional silanes verified the effectiveness of modifying surface hydrophilicity in the range of 0.10-1.00%. Below 0.10%, the contact angle reached as high as 58°, indicating no significant hydrophilic effect. Above 1.00%, although the contact angle could be reduced to below 30°, the increase in water vapor transmission rate slowed down to 4400 g·m⁻²·h⁻¹ and tended to plateau. Furthermore, excessive hydrophilic silanes may introduce VOC risks and affect the processing flowability of the compound. The experimental data showed that the range of 0.55-0.85% achieved good hydrophilicity of 42-34° while maintaining a high moisture transmission rate of 4200-4350 g·m⁻²·h⁻¹, proving that the upper limit of 1.00% balanced performance improvement with process controllability. The single-factor curing temperature experiment confirmed the process window of 80-120℃ through temperature gradient testing of 65-140℃. Below 80℃, the crosslinking reaction was incomplete, resulting in a tensile strength of only 0.73 MPa and a deterioration of the compression set to 15.5%. Above 120℃, although the performance could still be maintained in the 110-120℃ range, above 130℃, signs of excessive crosslinking or thermo-oxidative degradation began to appear, causing the strength to drop to 0.88 MPa and the deformation rate to rebound to 12.5%. The experimental data showed that 100-120℃ was the optimal curing temperature range, which ensured sufficient crosslinking and avoided thermal damage. The upper limit of 120℃ was set to provide a safety margin for industrial production.The boundary verification levels of the four sets of single-factor experiments were clearly defined. Porosity, cellulose nanocrystals, and hydrophilic silanes, as core structural and functional parameters, were listed as the first-level practical boundary verification objects. By setting two test points outside the upper and lower limits, the performance degradation trend after exceeding the scope of the claims was fully exposed. Curing temperature, as a process parameter, was listed as the second-level safety boundary verification, which focused on confirming the reliability and stability of the process window. All experiments used three parallel tests and calculated the standard deviation to quantify the data dispersion. The trend of the standard deviation increasing as the parameter deviates from the optimal range further confirmed the stability and repeatability of the material performance within the scope of the claims. The combined results of the four sets of single-factor experiments fully proved that the setting of the range of each core parameter in the technical solution of this invention is a scientific choice based on the laws of materials science and engineering practice experience. It not only ensures the excellent comprehensive performance of the material, but also ensures the operability and quality stability of industrial production, providing solid experimental data support for the rationality, reliability, and validity of the claims.

[0127] Aperture distribution map ( Figure 5 The correctness is reflected in its high consistency with the structural design and process parameters of Example 1: the oriented soluble particle template is composed of two grades of graded sodium chloride particles, with an average particle size of approximately 200 μm near the skin and approximately 500 μm far from the skin. These particles are oriented and pre-compressed in the order of small particle size layer → large particle size layer. Subsequently, after impregnation at 30 kPa low pressure and curing at 100℃, the template is dissolved, resulting in a sponge structure with an open porosity of 88.5%, a through-pore orientation index of 0.70, and a pore size gradient increasing from the near-skin side to the far-skin side. Therefore, the pore size distribution should exhibit a bimodal or broad-peak distribution with characteristic peaks or main peak regions of 200 μm and 500 μm, and a gradient characteristic from small to large in the cross-sectional direction. This distribution corroborates the measured high air permeability of 450 L·m⁻²·s⁻¹, proving that the pore size distribution shown in the figure above matches the target structure and functional parameters of the material. Therefore, it can be determined that it correctly reflects the pore structure characteristics of this example.

[0128] The performance of the examples and comparative examples is summarized in Table 1. The data in the table shows that porosity is a key factor affecting air permeability. Comparative Example 1, with an open porosity of only 82%, resulted in a permeability of only 350 L·m⁻²·s⁻¹, while Comparative Example 2, with an open porosity as high as 94%, achieved a permeability of 580 L·m⁻²·s⁻¹. However, excessively high porosity severely weakens the mechanical properties of the material, leading to a compression set of 18.5% and a tensile strength decrease to 0.58 MPa. The content of cellulose nanocrystals significantly enhances mechanical properties. Example 4, using 2.00% cellulose nanocrystals, achieved the highest tensile strength of 1.28 MPa and the lowest compression set of 8.5%, while Comparative Example 10, without any cellulose nanocrystals, resulted in a tensile strength of only 0.52 MPa. The strength of Comparative Example 13, despite containing cellulose nanocrystals, exhibited a high deformation rate of 20.5% and a low strength of 0.55 MPa due to insufficient curing conditions (70℃ × 1.25h) resulting in low crosslinking density. The content of hydrophilic silane directly affects the surface wettability of the material. Example 2 reduced the 30-second contact angle to 35° by introducing 0.75% hydrophilic silane. Comparative Example 9, while using a higher content of 1.15% hydrophilic silane to further reduce the contact angle to 28°, exceeded the scope of the claims and may pose a VOC risk. Comparative Example 8, with a hydrophilic silane content of less than 0.25%, and Comparative Example 11, with no hydrophilic silane added at all, resulted in a 30-second contact angle deterioration to 68° and 82°, respectively. The Si-H equivalent ratio and curing conditions of the crosslinking system are crucial to the integrity of the material's network structure. Comparative Example 12 used an insufficient crosslinking agent (Si–H and C=C). The equivalent ratio of 0.70 resulted in insufficient cross-linking, leading to increased material brittleness and a decrease in elongation at break to 285%. Comparative Example 13 exhibited high deformation rate and low strength due to insufficient cross-linking caused by excessively low curing temperature. The pore size gradient design affected the moisture permeability. Examples 1-4 achieved a water vapor permeability of 3850-4800 g·m⁻²·h⁻¹ through a gradient pore size structure on the near-skin and far-skin sides, while Comparative Example 1, with an open porosity of only 82%, experienced reduced pore connectivity, resulting in a moisture permeability of 3200 g·m⁻²·h⁻¹. In Comparative Example 3, the orientation index of only 0.50 led to an increase in pore tortuosity, resulting in a significant decrease in both air permeability and moisture permeability. Overall, Examples 1-4 achieved better results by controlling the open porosity to 85-91%, optimizing the cellulose nanocrystal content to 1.00-2.00%, setting the hydrophilic silane content to 0.45-0.75%, maintaining the Si-H equivalent ratio between 0.95-1.10, and selecting curing conditions of 95-105℃ with a temperature of 1.0-1.Within 5 hours, a comprehensive balance of air permeability, mechanical properties, hydrophilicity, and moisture permeability was successfully achieved. However, each comparative example deviated from the aforementioned parameter range, resulting in significant deterioration in one or more performance indicators. Even if individual comparisons, such as Comparative Example 2 and Comparative Example 9, showed slight advantages in a single indicator, they lacked practical value due to performance imbalances or exceeding the scope of the claims.

[0129] Figure 6 The correctness of this can be corroborated by the changes in characteristic absorption peaks: unmodified cellulose nanocrystals should exhibit typical broad peaks of O–H stretching vibration (approximately 3300–3400 cm⁻¹), C–H stretching vibration (approximately 2900 cm⁻¹), and sugar ring fingerprint bands of C–O–C and C–O stretching vibrations (approximately 1050–1160 cm⁻¹). After coupling modification with 3-methacryloxypropyltrimethoxysilane, the spectrum should retain the main cellulose backbone peaks and show or enhance the following signals: Si–O–C / Si–O–Si related absorption (overlapping bands with slight redshift / intensity changes in the approximately 1000–1130 cm⁻¹ range), Si–CH₃ related absorption (approximately 1250–1270 cm⁻¹ and approximately 800–850 cm⁻¹), methacrylyl C=O stretching (approximately 1715–1730 cm⁻¹, with slight shifts possible if there is partial condensation or hydrogen bonding environment), and C=C related absorption (approximately 1635–1645 cm⁻¹, with intensity changes due to different degrees of crosslinking or hydrolytic condensation). At the same time, the broad O–H peaks will narrow or decrease in intensity due to the substitution of surface hydroxyl groups by silane and changes in the hydrogen bond network. The aforementioned peak shapes and shift patterns are consistent with the chemical mechanism of silane coupling to the cellulose surface, thus proving that... Figure 6 The comparison of the FTIR transmission spectra of the modified and unmodified samples is accurate and chemically indicative.

[0130] Figure 7 and Figure 8 The sponge morphology of the proximal and distal dermal sides of Embodiment 1 of the present invention is shown respectively. Scanning electron microscopy clearly verifies the successful construction of the gradient pore structure. Figure 7 The pores on the near-skin side are concentrated at around 200 μm, with regular pore morphology and uniform pore wall thickness. This fine pore structure provides a soft touch upon contact with the skin and promotes rapid sweat absorption. Figure 8The results show a significant increase in pore size on the distal skin side, reaching approximately 500 μm. This large pore structure creates rapid moisture-wicking channels, facilitating the outward diffusion of water vapor. The pore sizes on both sides exhibit a gradient difference of approximately 2.5 times and are interconnected. This demonstrates that the graded installation and unidirectional pre-compression of the directional soluble particle template successfully achieved a directional gradient pore distribution from the proximal to the distal skin side. This asymmetric bidirectional gradient structure ensures both comfort at the skin contact interface and high overall air and moisture permeability. Morphological observation results are consistent with the air permeability of 450 L·m⁻²·s⁻¹ and water vapor permeability of 4200 L·m⁻²·s⁻¹ measured in Example 1. The excellent data of g·m⁻²·h⁻¹ corroborate each other, fully demonstrating the key role of gradient pore size design in realizing the material's function. At the same time, the smooth surface of the pore walls without obvious defects and the good pore connectivity indicate that the proper control of the curing process parameters enabled the silicone rubber matrix to fully crosslink and form a stable three-dimensional network structure. The uniform dispersion of cellulose nanocrystals in the pore wall matrix plays a reinforcing role. The successful modification of the pore wall surface by hydrophilic functional silane enhances the hydrophilicity. The high consistency between the microscopic morphology characteristics and the macroscopic performance test data provides intuitive and reliable experimental evidence for the scientificity and practicality of the technical solution of this invention.

[0131]

[0132]

[0133] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A water-permeable and breathable sponge, characterized in that, It includes a cross-linked polydimethylsiloxane continuous phase and a through-pore network, and has the following characteristics: a. The through-hole is formed by dissolving oriented soluble particle template, with an opening rate of 85-92%, an orientation index of not less than 0.60, a thickness of 2-8 mm, and a pore size gradient of 150-250 μm on the near-skin side and 400-600 μm on the far-skin side. b. The continuous phase is a silicone rubber network formed by crosslinking vinyl-terminated polydimethylsiloxane with a hydrosiloxane, wherein the hydrosiloxane is dimethylmethylhydrosiloxane or a methylhydrosiloxane-dimethylsiloxane copolymer; the crosslinking is a platinum-catalyzed hydrosilylation reaction; c. The sponge contains silane-coupled modified cellulose nanocrystals, with a mass fraction of 0.50-2.00%; d. The surface or bulk phase of the sponge contains a covalently fixed layer of a hydrophilic functional silane, wherein the hydrophilic functional silane is selected from 3-aminopropyltriethoxysilane and / or 3-glycidoxypropyltrimethoxysilane, and its total mass fraction in the finished sponge is 0.10–1.00%; e. The air permeability of the sponge, as measured by GB / T 5453-1997 at a pressure difference of 100 Pa, shall be not less than 400 L·m⁻²·s⁻¹; the covalent fixation of the hydrophilic functional silane is achieved by mixing 0.10–1.00 wt% of 3-aminopropyltriethoxysilane and / or 3-glycidoxypropyltrimethoxysilane into the composite prepolymer system, which, during the curing process, undergoes alkoxy hydrolysis-condensation and condensation with silanol on the pore wall / cellulose nanocrystal surface to form a covalent hydrophilic layer; this process does not participate in the hydrosilylation reaction.

2. The sponge according to claim 1, characterized in that, The silane-coupled modified cellulose nanocrystals were prepared according to the following steps: A1. Raw materials: 100 parts by weight of microcrystalline cellulose, 60-65% by weight of sulfuric acid, sodium hydroxide, and deionized water; A2. Acid hydrolysis: At 40-50℃, treat with sulfuric acid of 60-65% by mass at a mass ratio of acid solution to microcrystalline cellulose of 8:1-12:1 for 30-90 minutes to obtain cellulose nanocrystal dispersion; A3. Neutralization and washing: Neutralize with sodium hydroxide solution to pH 6.0-8.0, then wash repeatedly with deionized water to obtain a cellulose nanocrystal dispersion with a solid content of 2-5%; A4. Coupling: 3-(methacryloyloxy)propyltrimethoxysilane or 3-glycidoxypropyltrimethoxysilane is added to the dispersion, wherein the mass ratio of silane to cellulose nanocrystals is 2-10%, the mixture is stirred for 1-3 hours, and then washed and dried to obtain the silane-coupled modified cellulose nanocrystal powder.

3. The sponge according to claim 1, characterized in that, The oriented soluble particle template is prepared according to the following steps: C1. Raw material: Sodium chloride or sucrose; C2. Grading: Prepare two grades of particles, one with an average particle size of 150-250 μm and the other with an average particle size of 400-600 μm; C3. Oriented laying and pre-compression: Small-diameter layer and large-diameter layer are laid in sequence from near skin side to far skin side. The mass ratio of particles near skin side to far skin side is 1.0-2.

0. The whole is unidirectionally pre-compressed at 5-20MPa to form a 2-8mm thick oriented soluble particle template. The unidirectional pre-compression direction of the template is parallel to the orientation direction of the long axis of the through hole.

4. The sponge according to claim 1, characterized in that, The thickness of the proximal lateral lamina accounts for 30-60% of the total thickness, with an average pore size of 150-250 μm, while the average pore size of the distal lateral lamina is 400-600 μm.

5. The sponge according to claim 1, characterized in that, The mass ratio of hydrophilic functional silane to silane-coupled modified cellulose nanocrystals is 0.20-1.

00.

6. A method for preparing a water-permeable and air-permeable sponge as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of oriented soluble particle template; S2. Preparation of composite adhesive: 100 parts by weight of vinyl-terminated polydimethylsiloxane; hydrogen-containing siloxane crosslinking agent added according to Si–H / C=C equivalent ratio of 0.80–1.20; 0.50–2.00 parts by weight of silane-coupled modified cellulose nanocrystals; 0.10–1.00 parts by weight of hydrophilic functional silane; 5–50 ppm of platinum complex catalyst based on platinum content, the platinum complex catalyst being platinum(0)-1,3-diethylene-1,1,3,3-tetramethyldisiloxane; after mixing, degas under low pressure. S3. The composite adhesive is impregnated into the oriented soluble particle template under a low pressure environment of 10-50 kPa until it is completely filled; S4. Curing at 80-120℃ for 0.50-2.00 hours yields the composite template. S5. Dissolve the oriented soluble particle template with deionized water and dry it to obtain a water-permeable and air-permeable sponge.

7. The method for preparing a water-permeable and air-permeable sponge according to claim 6, characterized in that, The impregnation time for S3 is 10-20 minutes.

8. The method for preparing a water-permeable and air-permeable sponge according to claim 6, characterized in that, The soluble particle template dissolution process employs multi-stage countercurrent washing, with the washing liquid volume being 10-30 times the template volume.

9. The water-permeable and breathable sponge according to any one of claims 1-5 or the water-permeable and breathable sponge obtained by the preparation method according to any one of claims 6-8, for the application of water permeability, breathability, support and rebound in nursing and sports underwear, masks, underwear, goggles, clothing, shoes and mattresses.

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