PDMS-based green flexible composite material capable of synchronously responding to force and thermal stimulation and preparation technology of PDMS-based green flexible composite material

Abstract

The invention discloses a bifunctional PDMS / SrAl2O4: Eu < 2 + >, Dy < 3 + > flexible composite material synchronously responding to mechanical and thermal stimuli and a preparation technology, PDMS is used as a matrix, SrAl2O4: Eu < 2 + >, Dy < 3 + > fluorescent powder is subjected to surface modification and compounding, and a composite film with water resistance, high brightness and high flexibility is successfully prepared. The method effectively overcomes the defects of high brittleness and difficulty in independent molding of the fluorescent powder material, and expands the application potential of the fluorescent powder material in the flexible photoelectric field.

Description

Technical Field

[0001] This invention discloses a PDMS / SrAl2O4:Eu material that responds synchronously to mechanical and thermal stimuli. 2+ ,Dy 3+ Composite long-afterglow luminescent materials and their preparation techniques, through optimization of PDMS and SrAl2O4:Eu 2+ ,Dy 3+ The optimal ratio of PDMS to SAO enables efficient composite formation of long-afterglow luminescent powder within a PDMS matrix. This material maintains high brightness while exhibiting excellent flexibility, placing it within the field of optoelectronic functional materials technology. Background Technology

[0002] Rare earth-doped long-afterglow luminescent materials have been widely used in emergency lighting, near-infrared bio-imaging, anti-counterfeiting labels, and metal flaw detection. Among them, SrAl2O4:Eu 2+ ,Dy 3+ Long-afterglow materials have become a research hotspot due to their advantages such as high photoluminescence intensity, long afterglow lifetime, and mature preparation process.

[0003] Currently, a large amount of research focuses on SrAl2O4:Eu 2+ ,Dy 3+ The synthesis methods, phosphorescence mechanism, and surface polymer coating process of phosphors have been systematically revealed, showcasing their excellent luminescent properties. However, this material is inherently a brittle ceramic with low fracture toughness, making it prone to microcracks under mechanical stress, vibration, or impact, leading to surface wear or peeling and consequently, a decline in luminescent performance. More critically, the powdered form of SrAl2O4:Eu... 2+ ,Dy 3+ Lacking self-supporting flexibility and structural integrity, it is difficult to directly apply to strain-stress related scenarios. In 2010, SB Mishra et al. used SrAl2O4:Eu 2+ ,Dy 3+ Composites with EVA polymers were developed, but the resulting materials still had relatively low mechanical strength, failing to meet the requirements for high mechanical properties. In 2020, P. Jha et al. used PDMS as a matrix to support phosphors, which improved environmental stability to some extent, but the hydrophilic SrAl2O4:Eu 2+ ,Dy 3+ Interfacial incompatibility exists between long-afterglow materials and hydrophobic PDMS, resulting in weak interfacial bonding. Under high-energy impact, phosphor detachment or interfacial debonding easily occurs, severely affecting the material's lifespan. In recent years, research progress on combining long-afterglow materials with polymers to improve mechanical properties has been slow, mainly due to technical bottlenecks such as complex preparation processes, difficult sample encapsulation, easy powder agglomeration, and insufficient tensile strength.

[0004] Based on this, the present invention improves upon the SrAl2O4:Eu 2+ ,Dy 3+ The system underwent interface modification, which significantly improved the interfacial compatibility and bonding strength between the two phases, resulting in the development of a novel PDMS / SrAl2O4:Eu complex with excellent flexibility. 2+ ,Dy 3+ Composite materials will drive the further application of this type of long afterglow material in flexible optoelectronic functional devices. Summary of the Invention

[0005] This study successfully prepared a novel PDMS / SrAl2O4:Eu material with excellent flexibility. 2+ ,Dy 3+ Composite long afterglow material. Using SrAl2O4:Eu²⁺,Dy³⁺ phosphor as the luminescent medium. Take 1-3g of the powder, preheat to 30-100℃, add 1-2% (by weight of the powder) of diluted aluminate coupling agent, stir for 30-60 min, and then dry to obtain a hydrophobic modified SrAl2O4:Eu²⁺,Dy³⁺ sample. Weigh 5-10g of PDMS and stir for 10-20 min, add the modified powder and stir for 5-10 min, add 1mL of curing agent and stir at room temperature for 10-30 min, let stand for 45 min to degas, dry at 75-85℃ for 5 h, cool and demold to obtain the composite material.

[0006] This invention combines PDMS with SrAl2O4:Eu²⁺,Dy³⁺ long afterglow luminescent material, which significantly improves the environmental stability and hydrolysis resistance of phosphors, and successfully expands their application scope from traditional signage and lighting to the emerging field of strain-stress sensing.

[0007] Further research revealed that the fluorescence emission intensity of this composite film exhibits a regular response to temperature changes, demonstrating its potential for optical temperature sensing. This temperature-sensitive characteristic, combined with the material's inherent stress-responsiveness, makes it a bifunctional material capable of simultaneously responding to both mechanical and thermal stimuli. This breakthrough broadens the material's application scenarios, extending its use beyond structural health monitoring and flexible electronic skin to more complex applications requiring simultaneous, visualized, and wireless monitoring of temperature and stress. Attached Figure Description

[0008] Figure 1 This invention synthesizes SrAl2O4:Eu 2+ ,Dy 3+ XRD pattern of the composite material.

[0009] Figure 2 This invention synthesizes SrAl2O4:Eu 2+ ,Dy 3+Scanning electron microscope image of the composite material.

[0010] Figure 3 This invention synthesizes SrAl2O4:Eu 2+ ,Dy 3+ Excitation spectrum of the composite material.

[0011] Figure 4 This invention synthesizes SrAl2O4:Eu 2+ ,Dy 3+ Emission spectrum of the composite material.

[0012] Figure 5 This invention synthesizes SrAl2O4:Eu 2+ ,Dy 3+ Afterglow decay curve of composite material.

[0013] Figure 6 This invention synthesizes SrAl2O4:Eu 2+ ,Dy 3+ Tensile strength measurement results of composite materials prepared at different proportions.

[0014] Figure 7 This invention synthesizes SrAl2O4:Eu 2+ ,Dy 3+ Temperature-dependent fluorescence emission spectra of composite materials. Detailed Implementation

[0015] The detailed process of the SrAl2O4:Eu²⁺,Dy³⁺ composite material in this invention is described below: (1) This invention uses SrCO3, Al2O3, Eu2O3 and Dy2O3 aluminate coupling agents, PDMS and curing agent as raw materials, and H3BO3 as a flux. The amount of each raw material is calculated according to the stoichiometric ratio of SrAl2O4:Eu²⁺,Dy³⁺. The amount of flux H3BO3 added is 0~20% of the total raw material mass. The amount of aluminate coupling agent added is 1~2% of the phosphor mass.

[0016] (2) According to the stoichiometric ratio for preparing 2g of phosphor, weigh the corresponding amounts of SrCO3, Al2O3, Eu2O3, Dy2O3 and H3BO3 raw materials using a precision electronic balance, and mix and grind them thoroughly.

[0017] (3) Place the uniformly mixed powder raw material in a corundum crucible and then place it in a muffle furnace. Under a carbon reducing atmosphere, heat the material to 1200~1400℃ at a heating rate of 5℃ / min and calcine it at this temperature for 1~5 hours.

[0018] (4) After calcination, the sintered body is naturally cooled to room temperature. After grinding and sieving, high-brightness, pure-phase SrAl2O4:Eu²⁺,Dy³⁺ fluorescent powder is obtained.

[0019] (5) Weigh 1~3g of the fluorescent powder obtained in step (4), preheat to 50~60℃, then add 1~2% of the powder mass of diluted aluminate coupling agent, stir continuously for 30~60min, and dry to obtain a hydrophobic modified SrAl2O4:Eu²⁺,Dy³⁺ sample.

[0020] (6) Weigh 5~10g of PDMS matrix, stir for 10~20min, add the modified powder obtained in step (5), and continue stirring for 5~10min to mix it evenly.

[0021] (7) Add 1 mL of curing agent to the mixture obtained in step (6), stir at room temperature for 10-30 min, let stand for 45 min to degas, transfer to mold, and cure at 75-85℃ for 5 hours.

[0022] (8) After cooling to room temperature, demold to obtain a PDMS / SrAl2O4:Eu²⁺,Dy³⁺ composite material with both flexibility and hydrophobicity.

[0023] Figure 1 The SrAl2O4:Eu prepared in this invention 2+ ,Dy 3+ The XRD pattern of the composite material sample was consistent with the diffraction peaks of the standard card PDF#34-0379, indicating that the sample could be successfully composited and that the crystallinity of the phosphor remained intact at a ratio of 6PDMS:7SAO.

[0024] Figure 2 The prepared SrAl2O4:Eu 2+ ,Dy 3+ Scanning electron microscope images of long-afterglow luminescent material samples show the modified SrAl2O4:Eu 2+ ,Dy 3+ It is uniformly dispersed in the PDMS matrix and has a tight interface bond with no obvious agglomeration or gaps.

[0025] Figure 3 The prepared SrAl2O4:Eu 2+ ,Dy 3+ The excitation spectrum of the composite material sample is a broadband spectrum at 365 nm.

[0026] Figure 4 The prepared SrAl2O4:Eu 2+ ,Dy 3+The emission spectrum of the composite material sample shows that the sample has the highest emission peak at 520 nm and can emit bright green light under ultraviolet and visible light excitation.

[0027] Figure 5 The prepared SrAl2O4:Eu 2+ ,Dy 3+ The afterglow decay curves of the composite material samples show that the samples have good long afterglow performance.

[0028] Figure 6 This invention synthesizes SrAl2O4:Eu 2+ ,Dy 3+ The tensile strength measurement results of the composite materials prepared at different ratios show that the 6PDMS:7SAO ratio exhibits excellent flexibility and elastic deformation ability, and also has a certain tensile strength.

[0029] Figure 7 This invention synthesizes SrAl2O4:Eu 2+ ,Dy 3+ The temperature-dependent fluorescence emission spectrum of the composite material shows that the SrAl2O4:Eu composite material prepared at 35°C... 2+ ,Dy 3+ Composite materials have the highest emission spectral intensity.

Claims

1. A bifunctional PDMS / SrAl2O4:Eu material with excellent flexibility and synchronous response to mechanical and thermal stimuli. 2+ ,Dy 3+ The composite material and its preparation technology use SrAl2O4:Eu²⁺,Dy³⁺ phosphor as the luminescent material and PDMS as the flexible matrix. Take 1~3g of the phosphor and preheat it to 30~100℃. Add 1~10% of the powder mass of diluted aluminate coupling agent. Stir for 30~60min and dry to obtain a hydrophobic modified phosphor sample. Weigh 5~10g of PDMS and stir for 10~20min. Add the modified powder and stir for 5~10min. Add 1mL of curing agent and stir at room temperature for 10~30min. Let stand for 45min to degas. Finally, dry at 75~85℃ for 5h and cool to demold to obtain the composite material.

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