Hollow porous composite fiber, smart packaging material for hollow core fiber coupling connection

Abstract

The application discloses a kind of hollow porous composite fibers, and intelligent packaging material for hollow core optical fiber coupling connection, belong to optical fiber technical field, the hollow porous composite fiber includes shell layer and core layer, the shell layer includes polyurethane layer, the core layer includes ultraviolet response shape memory polymer material layer;The hollow porous composite fiber provided by the application can be applied to hollow core optical fiber coupling connection as intelligent packaging material, when being applied, only need ultraviolet irradiation to trigger material to occur accurate, controllable deformation, so that packaging material is adaptively shrunk and tightly wrapped optical fiber joint, realizes from mechanical exertion external force to material active adaptation intelligent packaging mode.

Description

Technical Field

[0001] This invention belongs to the field of optical fiber technology, specifically relating to a hollow porous composite fiber, an intelligent packaging material for hollow optical fiber coupling connection, and in particular, a hollow porous composite fiber, an intelligent packaging material, and a packaging method for hollow optical fiber coupling connection. Background Technology

[0002] Hollow-core optical fiber is considered a key transmission medium for next-generation communication and sensing systems due to its superior performance in terms of transmission rate, delay, and nonlinear effects. However, integrating hollow-core optical fiber into existing optical communication systems based on thermally expanded optical fiber faces the bottleneck of how to achieve low-loss, high-strength, and stable coupling connections. Unlike traditional solid-core fiber fusion splicing, the coupling connection between hollow-core optical fiber and thermally expanded optical fiber usually relies on precise physical alignment and mechanical fixation.

[0003] Currently, among existing packaging technologies, CN106383384A discloses a packaging system and method for connecting hollow-core optical fibers and solid-core optical fibers. This method relies on a complex two-dimensional displacement stage, a CCD vision monitoring system, and optical fiber clamps. After precision mechanical adjustment and alignment, it is fixed using UV-curing adhesive. Although this method can achieve a certain level of accuracy, the operation is cumbersome, and once the UV adhesive cures, it is irreversible, making it difficult to debug and maintain after packaging, resulting in poor flexibility. CN110412687A discloses a structure and its preparation method for coupling from a large-diameter hollow-core optical fiber to a thermally expanded-core optical fiber. This preparation method involves setting a coupling optical fiber with an end containing a spherical light-gathering part and an etched section of the optical fiber, and then performing five parts: fusion splicing, translation, burning, spherical formation, and insertion. The high temperature during fusion splicing can easily cause the precise air hole structure of the hollow-core optical fiber to collapse, destroying its light-guiding mechanism and increasing the complexity and cost of the system.

[0004] Therefore, a new type of intelligent packaging solution is needed that can achieve adaptive, high-strength packaging and reversible disassembly to meet the needs of optical devices in installation, commissioning and maintenance throughout their life cycle. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a hollow porous composite fiber and an intelligent encapsulation material for hollow optical fiber coupling connections.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a hollow porous composite fiber, the hollow porous composite fiber comprising a shell layer and a core layer, the shell layer comprising a polyurethane layer, and the core layer comprising a UV-responsive shape memory polymer material layer.

[0008] The hollow porous composite fiber provided by this invention uses polyurethane as a protective layer, which has a certain degree of light transmittance, and uses ultraviolet-responsive shape memory polymer material as a core layer. When it is used as an encapsulation material for hollow fiber coupling connection, the core layer can be triggered to undergo photo-induced shrinkage under ultraviolet light irradiation, thereby enabling the hollow porous composite fiber to adaptively and tightly wrap and fix the hollow fiber coupling connection connector. At the same time, the material can be expanded and restored by heating, realizing non-destructive disassembly.

[0009] The hollow porous composite fiber provided by this invention can ensure the mechanical stability of hollow fiber coupling and packaging, ultimately achieving efficient and non-contact fiber connection operation, and significantly improving packaging quality and reliability.

[0010] Meanwhile, the composite fiber of the present invention has a porous structure, the presence of which ensures the smooth shrinkage of the UV-responsive shape memory polymer material layer.

[0011] Preferably, the UV-responsive shape memory polymer material comprises poly(4-vinylpyridine)-b-poly(6-(4-butylazophenyl-4'-oxy)hexyl methacrylate) block copolymer (P4VP-b-PAzoMA block copolymer).

[0012] In the P4VP-b-PAzoMA block copolymer of the present invention, the PAzoMA segment is a photoresponsive reversible phase. Under ultraviolet light irradiation, the azophenyl group it includes undergoes trans-cis isomerization, which can drive the core porous structure to undergo precise and controllable shrinkage deformation, so that the hollow porous composite fiber can adaptively and tightly wrap and fix the optical fiber connector.

[0013] Preferably, the degree of polymerization of the block copolymer is 120-180, for example 120, 130, 140, 150, 160, 170, 180.

[0014] Preferably, in the block copolymer, the molar content of the azophenyl group in poly(6-(4-butylazophenyl-4'-oxy)hexyl methacrylate) is 30-50%, for example, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, etc.

[0015] The molar content of azophenyl groups in the block copolymer of the present invention is within the above-mentioned range, which can ensure the ultraviolet light response sensitivity and deformation recovery rate.

[0016] Preferably, the block copolymer is a block copolymer that has undergone cross-linking and curing treatment, with a cross-linking degree of 60-80%, such as 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, etc.

[0017] The P4VP segments in the P4VP-b-PAzoMA block copolymer of the present invention form a stable network phase through cross-linking, which can fix the initial porous expansion state of the core layer and ensure the stability of the shape memory effect.

[0018] Preferably, the thickness of the polyurethane layer is 100-120 μm.

[0019] Preferably, the ultraviolet transmittance of the polyurethane layer is ≥70%, such as 70%, 72%, 73%, 74%, 75%, 78%, 80%, 82%, 85%, 86%, 87%, 88%, 89%, etc.

[0020] The polyurethane layer of the present invention has excellent light transmittance, which enables ultraviolet light to effectively act on the ultraviolet-responsive shape memory polymer material layer to trigger a photoresponse.

[0021] Preferably, the polyurethane is a linear polyurethane, with a preferred weight-average molecular weight of 80,000-150,000 g / mol, such as 80,000 g / mol, 90,000 g / mol, 100,000 g / mol, 110,000 g / mol, 120,000 g / mol, 130,000 g / mol, 140,000 g / mol, 150,000 g / mol, etc., and a preferred PDI < 1.5, such as 1.49, 1.45, 1.42, 1.35, 1.3, etc.

[0022] The polyurethane layer described in this invention serves as a support layer, ensuring that the UV-responsive shape memory polymer material can be spun into fibers.

[0023] Preferably, the hollow porous composite fiber comprises pores with a diameter of 300-500 nm and a porosity of 40-60%.

[0024] Preferably, the total thickness of the hollow porous composite fiber is 300-400 μm.

[0025] Preferably, the hollow pores in the hollow porous composite fiber are arranged along the axial direction of the fiber.

[0026] The shape recovery rate of the UV-responsive shape memory polymer material described in this invention is ≥95%, such as 95%, 96%, 97%, 98%, 99%, etc. After 50 UV irradiation-heat recovery cycles, the deformation attenuation rate is ≤3%, such as 3%, 2.5%, 2%, 1.5%, 1%, etc. The heating recovery temperature is 60-80℃, and the recovery time is ≤5 min.

[0027] In a second aspect, the present invention provides a method for preparing hollow porous composite fibers as described in the first aspect, the method comprising:

[0028] S1. Prepare polyurethane spinning solution as shell spinning solution, prepare UV-responsive shape memory polymer material spinning solution as core spinning solution, and prepare deionized water as center spinning solution.

[0029] S2. Injection spinning is performed using microfluidic spinning, followed by solidification to obtain the hollow porous composite fiber.

[0030] This invention uses microfluidic spinning technology to prepare hollow porous composite fibers with a core-shell structure in an integrated manner. At the same time, by controlling spinning parameters (such as injection rate, coagulation conditions, etc.), stable control of fiber diameter, shell thickness, porosity and mechanical properties can be achieved.

[0031] The composite fiber described in this invention has porous pores formed by the self-assembly of P4VP-b-PAzoMA block copolymer, and can achieve reversible shrinkage-expansion during the photoresponse process.

[0032] Preferably, the injection rate of the shell spinning solution is 1.1-1.2 mL / min, the injection rate of the core spinning solution is 0.65-0.8 mL / min, and the injection rate of the center spinning solution is 0.45-0.55 mL / min.

[0033] Preferably, the preparation method further includes: after solidification, cross-linking and curing with 1,4-diiodobutane, with a cross-linking degree of 60-80%, such as 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, etc.

[0034] As a preferred embodiment of the present invention, the preparation method includes:

[0035] S1. Prepare polyurethane spinning solution as shell spinning solution, prepare UV-responsive shape memory polymer material spinning solution as core spinning solution, and prepare deionized water as center spinning solution, and inject them into the injection needle respectively.

[0036] S2. Set up three parallel microfluidic spinning needles, and control the injection rate of the shell spinning solution to 1.1-1.2 mL / min, the injection rate of the core spinning solution to 0.65-0.8 mL / min, and the injection rate of the center spinning solution to 0.45-0.55 mL / min by setting an injection pump, and then extrude.

[0037] S3. After extrusion, the fiber enters a coagulation bath, which is deionized water. Solvent exchange causes the fiber to solidify and take shape. Preferably, the length of the coagulation bath is 1-1.5 m, such as 1 m, 1.1 m, 1.2 m, 1.3 m, 1.4 m, 1.5 m, etc.

[0038] S4. After curing, the material is collected by a transfer roller at a rate of 10-20 r / min. After collection, it is cross-linked and cured using 1,4-diiodobutane vapor, with a cross-linking degree of 60-80%.

[0039] S5. After cross-linking and curing, place at room temperature for 18-24 h to obtain the hollow porous composite fiber for later use.

[0040] This invention utilizes deionized water as a coagulation bath and separates the phases through a non-solvent phase: the solvent (e.g., DMF) in the spinning solution dissolves in the deionized water, while the water simultaneously permeates into the polymer solution, causing a sharp decrease in the solubility of the polymer and resulting in liquid-liquid phase separation. The phase separation forms a polymer-rich phase (solidified into a fiber skeleton) and a polymer-poor phase (forming pores after water evaporation), thus forming the hollow porous structure described in this invention.

[0041] Preferably, the mass ratio of the shell spinning solution to the core spinning solution is (6-7):(4-3), that is, based on the sum of their masses being 100%, the mass percentage of the shell spinning solution is 60-70%, for example, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, etc.

[0042] Thirdly, the present invention provides a smart packaging material for hollow optical fiber coupling connection, comprising the hollow porous composite fiber described in the first aspect.

[0043] Fourthly, the present invention provides a packaging method for hollow optical fiber coupling connection, utilizing the smart packaging material described in the third aspect, the packaging method comprising:

[0044] (1) Place the parts to be connected, such as hollow optical fiber and thermally expanded optical fiber, inside the smart packaging material;

[0045] (2) The smart packaging material is irradiated with ultraviolet light to shrink the structure of the smart packaging material and realize the connection and packaging of hollow optical fiber and thermally expanded optical fiber.

[0046] The intelligent encapsulation material provided by this invention can cause the core layer to shrink and the shell structure to shrink under ultraviolet light irradiation, so that it can adaptively wrap and stably fix the connection part of the hollow optical fiber and the thermally expanded optical fiber.

[0047] The encapsulation method (usage method) of the encapsulation material provided by the present invention only requires ultraviolet irradiation and necessary heating, without the need for complex precision alignment equipment or high-temperature welding devices, and has a low cost.

[0048] Preferably, the intensity of the ultraviolet light irradiation is 10-30 mW / cm². 2 The irradiation time is 30-120 seconds.

[0049] Preferably, the method of use further includes: heating the smart packaging material to 60-80°C to disassemble or adjust the smart packaging material.

[0050] As a preferred embodiment of the present invention, the packaging method includes:

[0051] (1) The smart packaging material is set to adapt to the length of the connection part of the hollow fiber and the thermally expanded fiber, and the structure to be connected (the end to be connected) of the hollow fiber and the thermally expanded fiber is set inside the hollow structure of the smart packaging material.

[0052] (2) Irradiate the smart packaging material with ultraviolet light of wavelength 365 nm at an intensity of 10-30 mW / cm. 2 The irradiation time is 30-120 s, which triggers the trans-cis isomerization of the azophenyl groups in the P4VP-b-PAzoMA block copolymer in the core layer, causing the porous structure of the core layer to shrink, so that the composite fiber adaptively wraps and secures the hollow fiber connector. The wrapping pressure is 0.1-0.5 MPa, such as 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, etc.

[0053] (3) After irradiation, let it stand at room temperature for 10-20 min, such as 10 min, 12 min, 15 min, 18 min, 20 min, etc., so that the core layer P4VP crosslinking network forms a stable curing structure and the encapsulation is completed;

[0054] (4) If disassembly or adjustment is required, heat the smart packaging material to 60-80°C. The azophenyl groups in the core layer will restore the trans configuration, and the porous structure will expand, thus removing the wrapping.

[0055] Preferably, in the method of use, the positioning accuracy of the irradiated area is ≤0.5 mm by adjusting the ultraviolet irradiation area, for example, 0.5 mm, 0.4 mm, 0.3 mm, 0.2 mm, etc.

[0056] The intelligent packaging material and packaging method provided by this invention solve the contradiction between packaging strength and reversible operation, and provide direction for achieving high-performance, high-reliability and maintainable connection of hollow optical fibers.

[0057] The smart packaging material defined in this invention includes a light-controlled shape memory material, which has the unique property of directional light regulation: unlike the random deformation of ordinary light-responsive materials, the P4VP-b-PAzoMA block copolymer defined in this invention can achieve directional deformation of the pore structure through linearly polarized light; wherein, the isomerization of the azophenyl group under the action of polarized light has directional selectivity, which can drive the molecular chain to shrink and orient along a specific direction.

[0058] In this invention, the P4VP-b-PAzoMA block copolymer undergoes a dynamic process of reversible isomerization: when irradiated with ultraviolet light, the azophenyl group changes from a rigid trans configuration to a flexible cis configuration, and the molecular chain arrangement becomes loose and disordered, causing the pore structure of the porous membrane to shrink and deform; when annealed at temperature or irradiated again, the cis configuration reversibly changes back to the trans configuration, the molecular chain returns to a regular arrangement, and the pore structure returns to its initial expanded state. The isomerization process can be monitored by a UV-Vis spectrophotometer, and is manifested as alternating changes in the intensity of the characteristic absorption peak corresponding to the trans configuration.

[0059] The present invention also provides a hollow fiber connection assembly, comprising a hollow fiber, a thermally expanded fiber, and a smart encapsulation material as described in the third aspect. The smart encapsulation material is tightly wrapped around the connection portion of the hollow fiber and the thermally expanded fiber. The insertion loss of the connection portion is ≤0.5 dB, for example, 0.5 dB, 0.4 dB, 0.3 dB, etc., and the return loss is ≤-50 dB, for example, -50 dB, -52 dB, -55 dB, -56 dB, -58 dB, -60 dB, etc.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] (1) Achieving non-contact, adaptive intelligent packaging: This invention uses a UV-responsive shape memory polymer (P4VP-b-PAzoMA) with a specific block structure as the core material. Only UV light irradiation is needed to trigger the material to undergo precise and controllable deformation, so that the packaging material adaptively shrinks and tightly wraps the optical fiber connector, realizing an intelligent packaging mode from mechanically applying external force to the material actively adapting.

[0062] (2) The encapsulation is strong and can be disassembled without damage: The P4VP segments in the UV-responsive shape memory polymer material defined in this invention form a stable cross-linked network, ensuring the structural strength and long-term stability after encapsulation. The photothermal dual response characteristics of the PAzoMA segments allow the encapsulated part to quickly restore its original shape by heating (60-80℃), thereby achieving non-destructive disassembly and repeated adjustment, solving the irreversible maintenance problem of traditional adhesive encapsulation.

[0063] (3) Ensure excellent optical connection performance: The transparent polyurethane shell ensures efficient transmission of ultraviolet light to trigger deformation. At the same time, its own structure and hollow porous structure help reduce the influence of stress on the optical fiber. Combined with the adaptive uniform wrapping mechanism, it can effectively achieve precise alignment and fixation of the optical fiber, thereby achieving excellent optical performance with low insertion loss (≤0.5dB) and high return loss (≤-50dB).

[0064] (4) Controllable process and simple operation: The present invention uses microfluidic spinning technology to prepare core-shell fibers in an integrated manner. The fiber diameter, shell thickness, porosity and mechanical properties can be stably controlled by precisely adjusting spinning parameters (such as injection speed, coagulation conditions, etc.). The entire encapsulation process only requires ultraviolet irradiation and heating when necessary, without the need for complex precision alignment equipment or high-temperature welding devices, thus reducing costs. Attached Figure Description

[0065] Figure 1 A schematic diagram of the encapsulation for hollow fiber coupling connection;

[0066] Among them, 1-hollow core optical fiber; 2-thermally expanded core optical fiber; 3-smart packaging material. Detailed Implementation

[0067] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0068] Unless otherwise specified, the raw materials involved in the following specific embodiments of the present invention are all conventional materials in the art, and can be purchased from commercially available products. Some raw material information is as follows:

[0069] (1) P4VP-b-PAzoMA block copolymer-1: The preparation method is as follows: using reversible addition-fragmentation chain transfer (RAFT) polymerization.

[0070] S1. Using 2-dodecyl trithiocarbonate as a chain transfer agent and 4-vinylpyridine (4VP) as a monomer, the molar ratio of 4VP monomer to chain transfer agent was controlled at 75:1 to synthesize poly(4-vinylpyridine) (P4VP) macromolecular chain transfer agent with a degree of polymerization of approximately 75.

[0071] S2. Using P4VP macromolecular chain transfer agent as a RAFT reagent, the polymerization of 6-(4-butylazophenyl-4'-oxy)hexyl methacrylate (AzoMA) monomer and methyl methacrylate (MMA) was initiated. The molar ratio of AzoMA to MMA was approximately 2:3, and the molar ratio of the total monomer mixture to P4VP macromolecular chain transfer agent was controlled to be approximately 75:1, to obtain P4VP-b-PAzoMA block copolymer. The overall degree of polymerization of the product was approximately 150, and the molar content of azophenyl groups in the PAzoMA blocks was approximately 40%.

[0072] (2) P4VP-b-PAzoMA block copolymer-2: The degree of polymerization is 120, the degree of polymerization of P4VP is 75, and the molar content of azophenyl groups in the PAzoMA block is about 30%. The preparation method is as described in (1), wherein:

[0073] The molar ratio of AzoMA to MMA is controlled at approximately 3:7, so that AzoMA accounts for approximately 30% of the monomer mixture. The molar ratio of the total amount of monomer mixture to P4VP macromolecular chain transfer agent is controlled at approximately 45:1, so that the degree of second block polymerization reaches 45.

[0074] (3) P4VP-b-PAzoMA block copolymer-3: The degree of polymerization is 180, the degree of polymerization of P4VP is 90, and the molar content of azophenyl groups in the PAzoMA block is about 50%. The preparation method is as described in (1), wherein:

[0075] The molar ratio of AzoMA and MMA is controlled to be approximately 1:1, so that AzoMA accounts for approximately 50% of the monomer mixture; the molar ratio of the total amount of monomer mixture to P4VP macromolecular chain transfer agent is controlled to be approximately 90:1, so that the degree of second block polymerization reaches 90.

[0076] (4) Polyurethane-1: Its molecular weight is 150,000 g / mol. Polybutylene adipate diol (PBA, Mn=2000 g / mol, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) is used as the long-chain polyol, 1,4-butanediol (BDO) is used as the chain extender, and diphenylmethane diisocyanate (MDI) is used as the diisocyanate. The molar ratio of the feed is: MDI:PBA:BDO = 4.000:1.000:3.004. The preparation method is as follows:

[0077] PBA and BDO were dehydrated at 110℃ and -0.098 MPa vacuum for 3 h, respectively. MDI was melted at 45℃. The treated raw materials were then fed into the main barrel of a co-rotating twin-screw reactive extruder (screw diameter 40 mm, L / D=48, screw speed 180 rpm) in proportion by a high-precision metering pump through an independent feeding system. The polymerization temperature was set at 120℃. After polymerization, the material was cooled in a water bath, pelletized, and dried at 80℃ for 6 h to obtain polyurethane-1.

[0078] (5) Polyurethane-2: with a molecular weight of 120,000 g / mol, prepared by referring to the preparation method of polyurethane-1;

[0079] (6) Polyurethane-3: with a molecular weight of 80,000 g / mol, prepared by referring to the preparation method of polyurethane-1.

[0080] Example 1

[0081] This embodiment provides a hollow porous composite fiber, which consists of a shell layer and a core layer, wherein:

[0082] The shell is made of polyurethane-1 with a thickness of 105 μm and a 365 nm ultraviolet transmittance of 90%. The core layer is made of P4VP-b-PAzoMA block copolymer-1.

[0083] The hollow porous composite fiber comprises hollow pores arranged along the axial direction of the fiber, with a porosity of 45% and an average pore diameter of 320 nm.

[0084] The preparation method is as follows:

[0085] S1. Prepare the spinning solution:

[0086] Dissolve polyurethane-1 particles in N,N A shell spinning solution with a mass fraction of 12% was prepared in dimethylformamide (DMF); a core spinning solution with a mass fraction of 8% was prepared by dissolving P4VP-b-PAzoMA block copolymer-1 in chloroform, and deionized water was used as the central spinning solution.

[0087] S2. Microfluidic spinning:

[0088] A three-channel coaxial needle assembly was used to inject the three spinning solutions into separate injection pumps, with injection rates set as follows: 1.15 mL / min for shell spinning solution, 0.72 mL / min for core spinning solution, and 0.50 mL / min for center spinning solution.

[0089] S3. Solidification:

[0090] The extruded composite liquid stream is injected into a deionized water coagulation bath with a length of 1 m. Solvent exchange occurs during immersion at room temperature, causing the fiber to solidify and take shape.

[0091] S4. Cross-linking curing

[0092] The pre-solidified composite fibers were collected by a set of conveyor rollers (speed set at 15 r / min) and guided into a sealed container. 1,4-Diiodobutane vapor was introduced into the container and treated at room temperature for 2 h to induce quaternization crosslinking of the P4VP segments in the fiber core layer, with a crosslinking degree of approximately 70%.

[0093] S5. The composite fiber is left to stand at room temperature for 20 h to allow the solvent to evaporate completely and the structure to stabilize, thereby obtaining the hollow porous composite fiber.

[0094] Example 2

[0095] This embodiment provides a hollow porous composite fiber.

[0096] The difference from Example 1 is that, in this example, the injection rates in step S2 are as follows: 1.2 mL / min for the shell spinning solution, 0.8 mL / min for the core spinning solution, and 0.55 mL / min for the center spinning solution.

[0097] Example 3

[0098] This embodiment provides a hollow porous composite fiber, which consists of a shell layer and a core layer, wherein:

[0099] The shell is made of polyurethane-2 with a thickness of 100 μm and a 365 nm ultraviolet transmittance of 85%. The core layer is made of P4VP-b-PAzoMA block copolymer-2.

[0100] The hollow porous composite fiber comprises hollow pores that extend axially along the fiber axis, with a porosity of 40% and an average pore diameter of 400 nm.

[0101] The preparation method is as follows:

[0102] S1. Prepare the spinning solution:

[0103] Dissolve polyurethane-2 particles in N,N A shell spinning solution with a mass fraction of 12% was prepared in dimethylformamide (DMF); a core spinning solution with a mass fraction of 8% was prepared by dissolving P4VP-b-PAzoMA block copolymer-2 in chloroform, and deionized water was used as the central spinning solution.

[0104] S2. Microfluidic spinning:

[0105] A three-channel coaxial needle assembly was used to inject the three spinning solutions into separate injection pumps, with injection rates set as follows: 1.1 mL / min for shell spinning solution, 0.65 mL / min for core spinning solution, and 0.45 mL / min for center spinning solution.

[0106] S3. Solidification:

[0107] The extruded composite liquid stream is injected into a deionized water coagulation bath with a length of 1 m. Solvent exchange occurs during immersion at room temperature, causing the fiber to solidify and take shape.

[0108] S4. Cross-linking curing

[0109] The pre-solidified composite fibers were collected by a set of conveyor rollers (speed set at 18 r / min) and guided into a sealed container. 1,4-Diiodobutane vapor was introduced into the container and treated at room temperature for 1.5 h to induce quaternization crosslinking of the P4VP segments in the fiber core layer, with a crosslinking degree of approximately 60%.

[0110] S5. The composite fiber is left to stand at room temperature for 24 h to allow the solvent to evaporate completely and the structure to stabilize, thereby obtaining the hollow porous composite fiber.

[0111] Example 4

[0112] This embodiment provides a hollow porous composite fiber, which consists of a shell layer and a core layer, wherein:

[0113] The shell is made of polyurethane-3 with a thickness of 120 μm and a 365 nm ultraviolet transmittance of 80%. The core layer is made of P4VP-b-PAzoMA block copolymer-3.

[0114] The hollow porous composite fiber comprises hollow pores arranged along the axial direction of the fiber, with a porosity of 60% and an average pore diameter of 500 nm.

[0115] The preparation method is as follows:

[0116] S1. Prepare the spinning solution:

[0117] Dissolve polyurethane-3 particles in N,N A shell spinning solution with a mass fraction of 12% was prepared in dimethylformamide (DMF); a core spinning solution with a mass fraction of 8% was prepared by dissolving P4VP-b-PAzoMA block copolymer-3 in chloroform, and deionized water was used as the central spinning solution.

[0118] S2. Microfluidic spinning:

[0119] A three-channel coaxial needle assembly was used to inject the three spinning solutions into separate injection pumps, with injection rates set as follows: 1.15 mL / min for shell spinning solution, 0.72 mL / min for core spinning solution, and 0.50 mL / min for center spinning solution.

[0120] S3. Solidification:

[0121] The extruded composite liquid stream is injected into a deionized water coagulation bath with a length of 1.5 m. Solvent exchange occurs during immersion at room temperature, causing the fiber to solidify and take shape.

[0122] S4. Cross-linking curing

[0123] The pre-solidified composite fibers were collected by a set of conveyor rollers (speed set at 15 r / min) and guided into a sealed container. 1,4-Diiodobutane vapor was introduced into the container and treated at room temperature for 2.5 h to induce quaternization crosslinking of the P4VP segments in the fiber core layer, with a crosslinking degree of approximately 80%.

[0124] S5. The composite fiber is left to stand at room temperature for 18 h to allow the solvent to evaporate completely and the structure to stabilize, thereby obtaining the hollow porous composite fiber.

[0125] Application Example 1

[0126] This application example provides a method for hollow fiber coupling using the hollow porous composite fiber, as follows:

[0127] (1) Cut a sample of hollow porous composite fiber with a length of about 2 cm, prepare a hollow fiber (five-unit single-nested hollow fiber) and a thermally expanded fiber (G.652.D), and use a fiber optic cutter to make a connector with a flat end face.

[0128] (2) Insert the cut fiber segment into the splicing part of the hollow fiber and the thermally expanded fiber to be connected, so that the end faces of the two fibers are aligned and slightly in contact in the hollow channel inside the fiber.

[0129] (3) Use a UV LED point light source with an output wavelength of 365 nm, a spot diameter of about 2 mm, and an intensity adjusted to 25 mW / cm². 2 The light spot is precisely aligned and covered to cover the encapsulated fiber segment, and irradiated for 60 seconds. During this process, it can be observed that the fiber gradually and tightly wraps around the internal optical fiber due to the shrinkage of the core material.

[0130] (4) After irradiation, let the connection part stand at room temperature for 15 minutes to further stabilize and solidify the encapsulation structure and complete the encapsulation.

[0131] (5) Optionally, in order to verify the reversibility, the sealed connection part is placed in a hot air environment of 70°C and heated for 4 minutes. It is observed that the fiber gradually expands and relaxes, and it can be slid out from the fiber connector to achieve non-destructive disassembly. The fiber end face after disassembly is clean and there are no obvious residues.

[0132] Application Example 2

[0133] This application example provides a method for hollow fiber coupling connection using the hollow porous composite fiber.

[0134] The difference from Application Example 1 is that in this application example, the hollow fiber is a five-unit double-nested hollow fiber.

[0135] Performance testing

[0136] (1) Referring to the method of the application example, five hollow fiber-thermal expanded fiber connection component samples were prepared for each group of samples. Each group of samples was tested using an insertion loss / return loss integrated tester (MPM-1700 series) with the light source wavelength set to 1550 nm.

[0137] (2) Mechanical stability: Three samples were randomly selected from each group of samples after insertion loss / return loss testing. They were subjected to mechanical vibration (frequency 10-55 Hz, amplitude 1.5 mm, duration 2 h) and temperature cycling treatment (-20℃ to +60℃, 20 cycles). After treatment, hollow fiber coupling connection was performed according to application example 1, and then insertion loss and return loss were retested.

[0138] The test results are as follows:

[0139] Table 1

[0140]

[0141] As demonstrated by the embodiments and performance tests, the intelligent encapsulation material provided by the present invention can meet the application requirements of IL≤0.5 dB and RL≤-50 dB when used for hollow fiber coupling connection, and can be adapted to different types of hollow fiber structures. At the same time, after mechanical vibration and temperature cycling, the changes in insertion loss and return loss are both less than 0.05 dB, indicating that the encapsulation structure has good mechanical robustness and environmental stability.

[0142] As can be seen from the comparison between Example 1 and Example 2, the present invention can control the pore structure of hollow porous composite fibers by changing the process parameters of microfluidic spinning, thereby affecting the loss of hollow fiber-thermally expanded fiber connection components.

[0143] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A hollow porous composite fiber, characterized in that, The hollow porous composite fiber includes a shell layer and a core layer. The shell layer includes a polyurethane layer, and the core layer includes a UV-responsive shape memory polymer material layer. The UV-responsive shape memory polymer material includes a poly(4-vinylpyridine)-b-poly(6-(4-butylazophenyl-4'-oxy)hexyl methacrylate) block copolymer; The degree of polymerization of the block copolymer is 120-180; In the block copolymer, the molar content of azophenyl groups in poly(6-(4-butylazophenyl-4'-oxy)hexyl methacrylate) is 30-50%; The block copolymer is a cross-linked curing treatment block copolymer with a cross-linking degree of 60-80%; The ultraviolet transmittance of the polyurethane layer is ≥70%.

2. The hollow porous composite fiber according to claim 1, characterized in that, The thickness of the polyurethane layer is 100-120 μm.

3. The hollow porous composite fiber according to claim 1, characterized in that, The hollow porous composite fiber comprises pores with a diameter of 300-500 nm and a porosity of 40-60%. And / or, the total thickness of the hollow porous composite fiber is 300-400 μm.

4. A method for preparing hollow porous composite fibers as described in any one of claims 1-3, characterized in that, The preparation method includes: S1. Prepare polyurethane spinning solution as shell spinning solution, prepare UV-responsive shape memory polymer material spinning solution as core spinning solution, and prepare deionized water as center spinning solution. S2. Injection spinning is performed using microfluidic spinning, followed by solidification to obtain the hollow porous composite fiber.

5. The preparation method according to claim 4, characterized in that, The injection rate of the shell spinning solution is 1.1-1.2 mL / min, the injection rate of the core spinning solution is 0.65-0.8 mL / min, and the injection rate of the center spinning solution is 0.45-0.55 mL / min. And / or, the preparation method further includes: after solidification, crosslinking and curing with 1,4-diiodobutane, with a crosslinking degree of 60-80%.

6. A smart encapsulation material for hollow-core optical fiber coupling connections, characterized in that, It includes the hollow porous composite fiber according to any one of claims 1-3.

7. A method for encapsulating hollow optical fiber coupling connections, characterized in that, The encapsulation method, using the smart encapsulation material of claim 6, comprises: (1) Place the parts to be connected, such as hollow optical fiber and thermally expanded optical fiber, inside the smart packaging material; (2) The smart packaging material is irradiated with ultraviolet light to shrink the structure of the smart packaging material and realize the connection and packaging of hollow optical fiber and thermally expanded optical fiber.

8. The packaging method according to claim 7, characterized in that, The intensity of the ultraviolet light irradiation is 10-30 mW / cm². 2 The irradiation time is 30-120 seconds; And / or, the encapsulation method further includes: heating the smart encapsulation material to 60-80°C to disassemble or adjust the smart encapsulation material.

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