An iron powder induced heat discolorable polydimethylsiloxane fiber and a preparation method thereof

Abstract

This invention discloses a thermochromic polydimethylsiloxane fiber and its preparation method, comprising adding iron powder and thermochromic microcapsules to a mixed emulsion of polydimethylsiloxane and a curing agent, thereby endowing the polydimethylsiloxane fiber with a rapid-response thermochromic function, realizing remote non-contact rapid control of temperature and color changes. Compared with traditional thermochromic materials, the fiber prepared by this invention has a faster response speed, higher flexibility and plasticity, and expands the application scenarios, enabling its use in textiles, smart clothing, medicine, and temperature control, increasing the intelligence and application value of the material.

Description

Technical Field

[0001] This invention belongs to the field of smart materials technology, specifically relating to a polydimethylsiloxane fiber that exhibits thermochromic properties in response to iron powder, its preparation method, and its applications. Background Technology

[0002] In the current research context, thermochromic fiber materials have been widely used in textiles, medicine, and construction, capable of changing color according to changes in ambient temperature. However, traditional thermochromic fibers have certain limitations in terms of temperature response speed and controllability of color transition. To improve the performance of this type of material, this invention combines iron powder and polydimethylsiloxane (PDMS) as matrix materials and innovatively applies electromagnetic induction heating technology to the design and manufacture of thermochromic fiber materials.

[0003] Traditional thermochromic fibers rely on heat sources, such as human body temperature or ambient heat, to trigger color changes in the material. Due to the lack of effective control over the heat source, these materials often face problems such as slow temperature change response and inability to adjust in real time in practical applications. Therefore, improving the response speed of thermochromic fibers to temperature changes and their application potential in different scenarios has become a research focus. Summary of the Invention

[0004] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0005] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0006] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing polydimethylsiloxane fibers that are thermochromic due to iron powder.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0008] Polydimethylsiloxane and curing agent are mixed evenly, iron powder with a particle size of 100-150μm is added, and after stirring, vacuum is drawn to obtain spinning mother liquor;

[0009] Thermochromic microcapsules are added to spinning mother liquor and mixed evenly to obtain iron powder-induced thermochromic spinning solution.

[0010] Iron powder-induced thermochromic spinning solution is loaded into a syringe and injected into a coagulation bath through a needle hole under the push of a propeller, ultimately preparing polydimethylsiloxane fiber;

[0011] The amount of iron powder added is 5-10 wt% compared to the amount of polydimethylsiloxane fiber.

[0012] In a preferred embodiment of the method for preparing the iron powder-induced thermochromic polydimethylsiloxane fiber described in this invention, the amount of iron powder added relative to the amount of polydimethylsiloxane fiber is 5 wt%.

[0013] In a preferred embodiment of the method for preparing the iron powder-induced thermochromic polydimethylsiloxane fiber of the present invention, the mass ratio of the polydimethylsiloxane to the curing agent is 9-10:1.

[0014] In a preferred embodiment of the method for preparing the iron powder-induced thermochromic polydimethylsiloxane fiber of the present invention, the stirring time is 8-10 min and the vacuuming time is 30-50 min.

[0015] In a preferred embodiment of the method for preparing the iron powder-induced thermochromic polydimethylsiloxane fiber described in this invention, the thermochromic microcapsules are red and the color-changing temperature is 30–42°C.

[0016] In a preferred embodiment of the method for preparing the iron powder-induced thermochromic polydimethylsiloxane fiber of the present invention, the content of the thermochromic microcapsules is 2.5 to 4 wt% of the spinning solution.

[0017] In a preferred embodiment of the method for preparing the iron powder-induced thermochromic polydimethylsiloxane fiber of the present invention, the pinhole size is 18-19G.

[0018] In a preferred embodiment of the method for preparing polydimethylsiloxane fiber with iron powder induction thermochromic properties according to the present invention, the coagulation bath is an oil bath at 100-125°C.

[0019] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing polydimethylsiloxane fibers by means of iron powder induction thermochromic polydimethylsiloxane fibers.

[0020] Another objective of this invention is to overcome the shortcomings of the prior art and provide an application of iron powder-sensitive thermochromic polydimethylsiloxane fiber in smart textiles, wearable devices, medical thermotherapy, and dynamic visual displays.

[0021] Beneficial effects of this invention:

[0022] (1) This invention develops electromagnetic induction thermochromic fibers by combining iron powder with thermochromic pigments and PDMS matrix, thereby realizing remote non-contact rapid control of temperature and color changes.

[0023] (2) Compared with traditional thermochromic materials, the fibers prepared by this invention have a faster response speed, higher flexibility and plasticity, and can be used in textiles, smart clothing, medicine and temperature monitoring systems, which greatly expands their application scenarios and improves the intelligent performance and application value of the materials. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0025] Figure 1 This diagram illustrates the preparation process and color testing process of the polydimethylsiloxane fiber with iron powder-induced thermochromic properties in Example 1 of the present invention.

[0026] Figure 2 The mechanical properties of the iron powder-induced thermochromic polydimethylsiloxane fibers prepared in Example 1 and Comparative Example 1 of this invention are shown in the diagram.

[0027] Figure 3 The image shows the electromagnetic induction heating performance of the iron powder-induced thermochromic polydimethylsiloxane fibers prepared in Example 1 and Comparative Example 2 of this invention. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0031] The method for determining the color-changing properties of iron powder-induced thermochromic polydimethylsiloxane fibers according to this invention is as follows: Electromagnetically induction-heated color-changing fibers are fixed on a heating stage. The heating stage is set to a heating (cooling) rate of 1℃ / min. A thermal infrared imager is used to detect the color-changing temperature and color change process during the temperature rise and fall of the fiber surface, and the results are recorded. Alternatively, the iron powder-induced thermochromic polydimethylsiloxane fibers are placed in an alternating magnetic field. Electromagnetic induction heating causes the iron powder in the fibers to be heated and converted, driving the fiber color change. A thermal infrared imager is used to detect the changes in the fiber surface during the magnetic field changes, and the color changes are recorded.

[0032] The method for determining the color of polydimethylsiloxane fiber that is thermochromic due to iron powder in this invention is as follows: under artificial sunlight of 6500K, the CIE-1931 chromaticity coordinates, reflectance, and absorptivity are measured using a computer colorimeter and colorimeter.

[0033] The curing agent used in this invention is SYLGARD 186 silicone curing agent.

[0034] The red thermochromic microcapsules used in this invention are self-made, with a color-changing temperature of 31℃ and a particle size of 10μm. The preparation method is as follows: urea and formaldehyde are mixed evenly at a molar ratio of 1:1.5, and the pH of the solution is adjusted to 7-9. The mixture is reacted at a constant temperature of 70℃ for 1 hour to form a bone aldehyde resin pre-solution. A thermochromic ternary compound (tetradecyl alcohol, bisphenol A, and crystal violet lactone) is used as the core material, and a 5% concentration of gum arabic powder solution is gradually added as an emulsifier to form a stable solution. The pre-solution is slowly added to the core material while maintaining air stirring, and the reaction is continued at 70℃ for 1 hour. The wall material gradually forms and coats the core material to obtain microcapsules. After cooling to room temperature, the microcapsules are obtained by centrifugation.

[0035] The Fe powder used in this invention is high-purity metallic iron powder with a particle size of 112 μm.

[0036] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0037] Example 1

[0038] This embodiment provides a method for preparing polydimethylsiloxane fibers that exhibit thermochromic properties induction by iron powder, specifically as follows:

[0039] (1) Mix polydimethylsiloxane (PDMS) and curing agent at a mass ratio of 10:1, add 5wt% iron powder with a particle size of 100μm, stir for 10min and then vacuum for 30min to obtain spinning mother liquor.

[0040] (2) Add red thermochromic microcapsules with a color change temperature of 31℃ to the spinning mother liquor, mix evenly to obtain iron powder-induced thermochromic spinning solution, wherein the content of red thermochromic microcapsules is 4wt%.

[0041] (3) The above electromagnetic induction thermochromic spinning solution is loaded into a syringe and injected into an oil bath at 100°C through a 19G needle hole under the push of the pusher, and finally iron powder induction thermochromic polydimethylsiloxane fiber is prepared.

[0042] Example 2

[0043] This embodiment provides a method for preparing thermochromic fibers, specifically:

[0044] (1) Mix polydimethylsiloxane (PDMS) and curing agent at a mass ratio of 9:1, add 10wt% iron powder with a particle size of 150μm, stir for 8min and then vacuum for 50min to obtain spinning mother liquor.

[0045] (2) Add red thermochromic microcapsules with a color change temperature of 31℃ to the spinning mother liquor, mix evenly to obtain iron powder-induced thermochromic spinning solution, wherein the content of red thermochromic microcapsules is 3wt%.

[0046] (3) The above-mentioned iron powder thermochromic spinning solution was loaded into a syringe and injected into an oil bath at 125°C through an 18G needle hole under the push of the pusher, and finally iron powder thermochromic polydimethylsiloxane fiber was prepared.

[0047] Example 3

[0048] This embodiment provides a method for preparing thermochromic fibers, specifically:

[0049] (1) Mix polydimethylsiloxane (PDMS) and curing agent at a mass ratio of 9:1, add 10wt% iron powder with a particle size of 150μm, stir for 8min and then vacuum for 45min to obtain spinning mother liquor.

[0050] (2) Red thermochromic microcapsules with a color change temperature of 31℃ were added to the spinning mother liquor and mixed evenly to obtain a spinning solution with iron powder induction thermochromic properties, wherein the content of red thermochromic microcapsules was 2.5wt%.

[0051] (3) The above-mentioned iron powder-induced thermochromic spinning solution was loaded into a syringe and injected into an oil bath at 125°C through a 19G needle hole under the push of the pusher, and finally iron powder-induced thermochromic polydimethylsiloxane fiber was prepared.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 1 is that the content of iron powder in step (1) is adjusted to 10wt%, 20wt%, 30wt%, 40wt%, and 50wt% to prepare the iron powder-induced thermochromic polydimethylsiloxane fiber of this comparative example.

[0054] The mechanical properties of the iron powder-induced thermochromic polydimethylsiloxane fibers prepared in Example 1 and Comparative Example 1 were measured, and the results are as follows: Figure 2 As shown.

[0055] from Figure 2 As can be seen, when the iron powder content is between 5 and 10 wt%, the polydimethylsiloxane fibers exhibiting iron powder-induced thermochromic properties all demonstrate good elasticity, with an elongation exceeding 250%. The elasticity is best at an iron powder content of 5 wt%, with an elongation approaching 300%. However, when the iron powder content exceeds 10%, both elasticity and elongation decrease.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that the iron powder particle size in step (1) was adjusted to 200 μm and 300 μm respectively, and polydimethylsiloxane fiber with iron powder induction thermochromic effect was prepared.

[0058] The electromagnetic induction heating properties of the iron powder-induced thermochromic polydimethylsiloxane fibers prepared in Example 1 and Comparative Example 2 were measured, such as... Figure 3 As shown.

[0059] from Figure 3 As can be seen, iron powder with a particle size of 100μm has the best heating effect, followed by 200μm iron powder, and 300μm iron powder has the worst heating effect. This is because 100μm iron powder has a smaller particle size, a larger surface area, and better thermal conductivity, thus achieving the best heating effect. After a fixed heating time of 20s, the heating temperature of 100μm iron powder can reach 41.8℃.

[0060] Comparative Example 3

[0061] The difference between this comparative example and Example 1 is that the mass ratio of PDMS and curing agent in step (1) is adjusted to 5:1, 6:1, 7:1, 8:1, and 9:1, respectively, to prepare polydimethylsiloxane fibers with iron powder-induced thermochromic properties.

[0062] The mechanical properties of the polydimethylsiloxane fibers prepared in Example 1 and Comparative Example 3 were measured, and the results are shown in Table 1.

[0063] Table 1 Comparison of mechanical properties of polydimethylsiloxane fibers prepared with different mass ratios

[0064]

[0065] As shown in Table 1, when the mass ratio of PDMS and curing agent is relatively low, the prepared polydimethylsiloxane fibers are relatively rigid and brittle. When the mass ratio of polydimethylsiloxane to curing agent is 10:1, the prepared polydimethylsiloxane fibers exhibit the best flexibility, can undergo large deformations without breaking, and have good plasticity.

[0066] Comparative Example 4

[0067] The difference between this comparative example and Example 1 is that the pinhole size in step (3) is adjusted to 14G, 18G, 20G, and 25G to prepare polydimethylsiloxane fiber with iron powder induction thermochromic properties.

[0068] The spinnability of the iron powder-induced thermochromic polydimethylsiloxane fibers prepared in Example 1 and Comparative Example 4 was tested, and the results are shown in Table 2.

[0069] Table 2 Comparison of spinnability of polydimethylsiloxane fibers prepared with needles of different specifications

[0070]

[0071] As shown in Table 2, different needle sizes significantly impact fiber properties and spinning processes. The 14G needle, due to its larger inner diameter, allows for smoother spinning, but the excessively large fiber diameter (1.65mm) makes it unsuitable for fine weaving and results in poor curing. The 18G needle offers a balanced performance in fiber diameter and process stability, approaching that of the 19G needle. The 19G needle achieves the optimal balance between fiber fineness, spinnability, and curing effect, with a moderate fiber diameter, high process stability, and excellent curing performance, making it the final best choice. In contrast, while the 20G and 25G needles can produce finer fibers, their small inner diameter causes the spinning solution to solidify inside the needle, clogging it and significantly reducing process stability, sometimes even preventing normal spinning.

[0072] In summary, the 19G needle ensures fiber fineness while maintaining good process stability, balancing performance and processing difficulty, making it the best choice for wet spinning.

[0073] Comparative Example 5

[0074] The difference between this comparative example and Example 1 is that the content of red thermochromic microcapsules in step (2) was adjusted to 2wt%, 2.5wt%, 3wt%, 5wt%, and 6wt%, respectively, to prepare polydimethylsiloxane fibers that are thermochromic induction by iron powder.

[0075] The polydimethylsiloxane fibers prepared in Example 1 and Comparative Example 5 were subjected to comprehensive performance testing, and the results are shown in Table 3.

[0076] Table 3 Comparison of comprehensive properties of polydimethylsiloxane fibers prepared with different contents of thermochromic powder

[0077]

[0078] According to Table 3, after comprehensive evaluation of various factors, fibers prepared with thermochromic microcapsules in the range of 2.5–4 wt% exhibit balanced performance in key indicators such as color change, spinnability, spinning solution viscosity, and cost. While formulations with contents below or above this range each have their own characteristics, they all have significant limitations and cannot meet application requirements.

[0079] In summary, this invention develops electromagnetically inductive thermochromic fibers by combining iron powder and thermochromic pigments with a PDMS matrix, enabling remote, non-contact, and rapid control of temperature and color changes. Furthermore, compared to traditional thermochromic materials, the fibers prepared in this invention exhibit faster response speeds, greater flexibility and plasticity, and can be used in textiles, smart clothing, medicine, and temperature monitoring systems, greatly expanding their application scenarios and enhancing the material's intelligent performance and application value.

[0080] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a polydimethylsiloxane fiber that exhibits thermochromic properties in response to iron powder, characterized in that: include, Polydimethylsiloxane and curing agent are mixed evenly, iron powder with a particle size of 100~150μm is added, and after stirring, vacuum is drawn to obtain spinning mother liquor; Thermochromic microcapsules are added to spinning mother liquor and mixed evenly to obtain iron powder-induced thermochromic spinning solution. Iron powder-induced thermochromic spinning solution is loaded into a syringe and injected into a coagulation bath through a needle hole under the push of a propeller, ultimately preparing polydimethylsiloxane fiber; The amount of iron powder added relative to the amount of polydimethylsiloxane fiber is 5-10 wt%. The content of the thermochromic microcapsules is 2.5~4 wt% of the spinning solution.

2. The method for preparing the iron powder-induced thermochromic polydimethylsiloxane fiber as described in claim 1, characterized in that: The amount of iron powder added is 5 wt% relative to the amount of polydimethylsiloxane fiber.

3. The method for preparing iron powder-induced thermochromic polydimethylsiloxane fiber as described in claim 1, characterized in that: The mass ratio of polydimethylsiloxane to curing agent is 9~10:

1.

4. The method for preparing iron powder-induced thermochromic polydimethylsiloxane fiber as described in claim 1, characterized in that: The stirring time is 8-10 minutes, and the vacuuming time is 30-50 minutes.

5. The method for preparing iron powder-induced thermochromic polydimethylsiloxane fiber as described in claim 1, characterized in that: The thermochromic microcapsules are red, and the color-changing temperature is 30~42℃.

6. The method for preparing the iron powder-induced thermochromic polydimethylsiloxane fiber as described in claim 1, characterized in that: The pinhole size is 18~19G.

7. The method for preparing the iron powder-induced thermochromic polydimethylsiloxane fiber as described in claim 1, characterized in that: The coagulation bath is an oil bath at 100~125℃.

8. A polydimethylsiloxane fiber with iron powder induction thermochromic properties prepared by any one of the preparation methods described in claims 1 to 7.

9. The application of the iron powder-sensitive thermochromic polydimethylsiloxane fiber as described in claim 8 in smart textiles, wearable devices, medical thermotherapy, and dynamic visual displays.

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