A dual responsive photoresist composition and use thereof

Abstract

The application discloses a double-response photoresist composition and application thereof. The photoresist composition comprises a functional monomer, a polymer and a photoinitiator. The functional monomer, the polymer and the photoinitiator in the composition are subjected to a polymerization reaction under irradiation of a femtosecond laser, the functional monomer is combined into the polymer chain, thereby realizing intelligent response to double stimulation of pH and temperature, and the photoresist composition has a lower femtosecond laser direct writing threshold and a faster femtosecond laser direct writing speed. The photoresist composition is mostly an olefin substance, raw materials of which are easy to obtain and easy to synthesize, and the acquisition process of the intelligent material is simplified.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photoresist and laser direct writing technology. More particularly, it relates to a dual-responsive photoresist composition and its application. BACKGROUND

[0002] Femtosecond laser processing technology is an important means to realize microstructure preparation. This technology uses femtosecond laser as light source to irradiate photoresist, so that the photoresist at the irradiation site absorbs two or more photons at the same time and undergoes polymerization reaction. Therefore, femtosecond laser direct writing technology has the ability of high precision, no mask, breaking through the optical diffraction limit, and processing three-dimensional microstructure. It is currently widely used in the preparation of micro-nano robots, microfluidic structures and optical structures, etc. Photoresist is a material system that has two-photon absorption of femtosecond laser, but the microstructure obtained by using traditional commercial photoresist and inorganic non-metallic materials at the present stage cannot flexibly change its own structure after processing, and has no stimulus response or controllable self-adaptive deformation ability. CN113835296A discloses a femtosecond laser direct writing photoresist composition, which relates to a combination of acrylate monomers, photoinitiators and polymers. Through specific structure of monomers and polymers, the photoresist composition has dual-color photosensitivity, which not only improves the femtosecond laser direct writing precision, but also reduces the femtosecond laser direct writing threshold and enhances the mechanical strength. However, the technical concept of stimulus response is not involved in the document.

[0003] At present, a class of stimulus-responsive materials, also known as smart materials, appears in the field. They can receive external environmental stimulus signals and change their molecular structure or state according to specific trigger factors (such as heat, light, electric and magnetic fields, pH, oxidizing and reducing agents, gas, etc.), thereby affecting their physical or chemical properties and embodying corresponding functions. These stimulus-responsive materials are often considered intelligent because they can sense the surrounding environment and produce human-controllable responses. Stimulus-responsive materials have been used in fields such as sensors, actuators, wearable devices, and biomedical devices. While people are increasingly interested in smart materials and their wide range of applications, they have begun to combine smart materials with microstructures to take full advantage of their material properties. However, the preparation of such stimulus-responsive microstructures has problems such as long manufacturing time, high cost, and limited available materials, and the manufacturing of stimulus-responsive microstructures remains challenging.

[0004] Therefore, it is necessary to develop a photoresist composition with multiple stimulus-responsive properties to realize the preparation of multiple response microstructures. SUMMARY

[0005] Based on the above defects, the first object of the present application is to provide a dual-responsive photoresist composition. The functional monomer and polymer in the photoresist composition are initiated to polymerize under the action of a femtosecond laser under the action of a photoinitiator, the functional monomer is combined into the polymer chain, thereby realizing the intelligent response to the dual stimulation of pH and temperature, and at the same time, the photoresist composition has a lower femtosecond laser direct writing threshold and a fast femtosecond laser direct writing speed.

[0006] The second object of the present application is to provide an application of the photoresist composition as above in the preparation of a dual-responsive microstructure. The photoresist composition prepared by the present application can be quickly formed in the femtosecond laser irradiation area, and a complex three-dimensional microstructure with high resolution is obtained; the obtained microstructure can realize stable and repeatable temperature response and pH response behavior without adding additional substances.

[0007] To achieve the above first object, the present application adopts the following technical solutions:

[0008] The present application discloses a dual-responsive photoresist composition, comprising a functional monomer, a photoinitiator and a polymer.

[0009] The functional monomer comprises an acrylic ester monomer with the following structural formula I and an acrylic ester monomer with the following structural formula II.

[0010]

[0011] wherein m1 represents an integer of 1-50, and R1 and R2 each represent a linear or branched alkyl group with 1-5 carbon atoms.

[0012] X-(Y) m2 Ⅱ.

[0013] wherein X represents a linear or branched alkyl group with 1-50 carbon atoms, and m2 represents an integer of 1-20.

[0014] Y represents -OOC-CR3=CH2; and R3 represents methyl or hydrogen.

[0015] The polymer is a polymer with the following structural formula III.

[0016]

[0017] In the technical scheme of the present application, the functional monomer comprises two kinds of acrylic ester monomers of structural formula I and structural formula II, the acrylic ester monomer of structural formula I is used in combination with the monomer of structural formula II under the action of a photoinitiator and a femtosecond laser to be polymerized onto a polymer chain to form a microstructure having a dual response characteristic to pH and temperature, the microstructure can be deformed according to environmental changes at different pH and temperature to realize stable and repeatable temperature response and pH response behaviors, the photoresist composition is mainly an olefin substance, raw materials are easy to obtain and easy to synthesize, the obtaining process of the smart material is simplified, the femtosecond laser direct writing threshold is low, the femtosecond laser direct writing speed is fast, and the photoresist composition is expected to be widely applied in the field of smart materials.

[0018] Specifically, structural formula I is a kind of tertiary amine-based acrylic ester monomer, due to the presence of the monomer, pH and temperature can be responded, the inventors found that the monomer combined with a polymer chain of a specific structure can produce a certain stimulation response behavior, but the processing difficulty is large, the stability is poor, and the formability is low, in order to improve the above problems, another kind of acrylic ester monomer of structural formula II is introduced, which mainly plays a crosslinking role in the technical scheme of the present application to improve the stability and formability of the photoresist.

[0019] Further, the average molecular weight of the polymer is 200-20000; preferably, the average molecular weight of the polymer is 500-5000; more preferably, the average molecular weight of the polymer is 700-3000.

[0020] Further, m1 in structural formula I represents an integer of 1-20; preferably, m1 represents an integer of 1-10.

[0021] Further, R1 in structural formula I represents a linear or branched alkyl group of C1-C3; R2 represents a linear or branched alkyl group of C1-C2.

[0022] Further, X in structural formula II represents a linear or branched alkyl group of C1-C30; preferably, the hydrogen of X in structural formula II is selectively substituted by a hydroxyl group, a halogen, a carboxyl group or an amino group.

[0023] Further, m2 represents an integer of 1-10; preferably, m2 represents an integer of 3-6.

[0024] Further, the structural formula I has a structure as shown in any one of I-1 to I-3:

[0025]

[0026] Further, the photoinitiator is selected from the group consisting of two-photon absorption photoinitiators; preferably, the photoinitiator includes but is not limited to one or more of diphenyl ketone, 2,2-diethoxy-1-phenylhexanone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0027] Further, the photoresist composition comprises 5-95 parts by weight of the functional monomer, 5-80 parts by weight of the polymer, and 0.01-20 parts by weight of the photoinitiator.

[0028] Further, the photoresist composition comprises 10-50 parts by weight of the functional monomer, 10-60 parts by weight of the polymer, and 0.01-10 parts by weight of the photoinitiator.

[0029] To achieve the above-mentioned second object, the application adopts the following technical scheme:

[0030] The application discloses an application of the photoresist composition in preparing a dual-response microstructure, and the specific steps for preparing the microstructure are as follows:

[0031] (1) The functional monomer, the photoinitiator, and the polymer are mixed in a brown glass container in a yellow light darkroom according to a proportion, and the photoresist composition is obtained after stirring;

[0032] (2) The photoresist composition is dropped on a substrate, and the photoresist composition is irradiated by using a femtosecond laser;

[0033] (3) The irradiated photoresist composition is developed in a developing solution, and a dual-response microstructure is obtained.

[0034] The microstructure can be designed by a femtosecond laser processing system, and coordinates are generated as a femtosecond laser processing path, in the actual preparation process, various shapes of three-dimensional microstructures, such as a micro-shaped platform structure and a micro-arm structure, can be obtained according to application needs.

[0035] Further, the substrate includes but is not limited to a glass sheet, a silicon wafer, a flexible resin film, a quartz sheet, sapphire, or conductive glass ITO.

[0036] Further, the wavelength of the femtosecond laser is 200-1100 nm; the power range of the femtosecond laser is 5-40 mW; and the scanning speed range is 5-100 μm / s.

[0037] The application has the following beneficial effects:

[0038] (1) The photoresist composition provided by the application has a lower two-photon processing threshold, and can realize faster speed processing.

[0039] (2) The photoresist composition provided by the application has a dual response characteristic, and the microstructure obtained by processing can realize stable and repeatable temperature response and pH response behavior.

[0040] (3) The photoresist composition provided by the application is mostly olefinic substance, and the raw material is easy to obtain and easy to synthesize, which simplifies the obtaining process of intelligent materials.

[0041] Therefore, the photoresist composition provided by the application realizes the dual response characteristic of the microstructure by using the functional monomer and polymer with a specific structure, simplifies the obtaining process of intelligent materials, reduces the two-photon processing threshold, and improves the processing efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0042] The specific embodiments of the application will be further described in detail below with reference to the accompanying drawings.

[0043] Figure 1 A schematic diagram of a femtosecond laser processing system is shown.

[0044] Figure 2 The response of the dual-response micro-shaped square platform structure processed by the photoresist composition described in Example 1 to different pH values is shown.

[0045] Figure 3 The response of the dual-response micro-shaped square platform structure processed by the photoresist composition described in Example 2 to different temperatures is shown.

[0046] Figure 4 The response of the dual-response micro-arm structure processed by the photoresist composition described in Example 3 to different pH values is shown.

[0047] Figure 5 The response of the dual-response micro-arm structure processed by the photoresist composition described in Example 4 to different temperatures is shown. DETAILED DESCRIPTION

[0048] In order to more clearly illustrate the application, the application will be further described below in conjunction with preferred embodiments and drawings. In the drawings, similar components are denoted by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative and not limiting, and should not limit the scope of protection of the application.

[0049] Unless otherwise specified, the raw materials used in the present application are commercially available, and the stimulus response behavior of the photoresist composition and microstructure prepared by the raw materials is not related to the source of the raw materials.

[0050] Example 1

[0051] a) First, a clean 5 mL glass bottle with a cap was prepared, and 0.53 g of polyethylene glycol diacrylate, 0.15 g of dimethylaminoethyl methacrylate, 0.01 g of 2,4,6(trimethylbenzoyl) diphenylphosphine oxide, 0.01 g of 2-hydroxy-2-methyl-l-phenyl-l-propanone and 0.3 g of pentaerythritol triacrylate were sequentially added. Then, a clean magnetic stir bar was added, the glass bottle was wrapped with aluminum foil, and after being labeled, it was placed on a magnetic stirrer to stir for 4 hours to clarity and transparency under light protection. A photoresist composition was obtained and was ready for use.

[0052] b) A rectangular glass cover slide with a thickness of 0.15 mm was prepared, and the glass cover slide was ultrasonically cleaned in deionized water containing detergent for 30 minutes, followed by repeated ultrasonic cleaning with deionized water for 6 times, and then dried in an oven. The dried glass cover slide was immersed in a 5 wt% KH-570 / toluene solution for 2 hours, and then the glass cover slide was quickly cleaned with anhydrous ethanol and dried.

[0053] c) The femtosecond laser processing system used in the present application is shown in FIG. 1. The wavelength of the femtosecond laser is 780 nm, and the magnification of the objective lens used is 60 times, and the numerical aperture is 1.42. The prepared photoresist composition was dropped on the cleaned glass cover slide, and then the glass cover slide was placed on the piezoelectric moving stage of the femtosecond laser processing system. The designed square platform structure was prepared using a femtosecond laser power of 30 mW and a scanning speed of 40 μm / s. The laser moving path was composed of continuous coordinates, and the designed processing model was scaled by computer software and the coordinates were generated as the femtosecond laser processing path. Figure 1

[0054] d) After the processing was completed, the glass cover slide was removed from the piezoelectric moving stage, and the unreacted photoresist was removed with ethanol. After the ethanol was naturally evaporated, the designed microstructure with dual response characteristics was obtained, which was a suspended square platform structure supported by a 8 μm diameter cylindrical structure, and the side length of the square platform structure was 28 μm.

[0055] e) Then, the square microstructure with a side length of 28 μm after processing was placed in a solution of dilute hydrochloric acid and sodium hydroxide with a pH value of 1 and 13, and the pH response characteristics of the microstructure were observed, and the results are shown in FIG. 2. It was found from FIG. 2 that the length of the microstructure was 28 μm when no acid was added, the microstructure swelled and the length increased to 33 μm after being soaked in an acid solution with a pH value of 1, and when the microstructure was transferred from the acid solution with a pH value of 1 to an alkali solution with a pH value of 13, the size of the microstructure decreased and the length decreased to 29 μm, which fully demonstrated the pH response. Figure 2 Figure 2

[0056] Example 2

[0057] ​​​a) First, prepare a clean 5mL glass bottle with a cap. Add 0.53g of polyethylene glycol diacrylate, 0.15g of dimethylaminoethyl methacrylate, 0.01g of 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, 0.01g of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 0.3g of pentaerythritol triacrylate in sequence. Then add a clean magnetic stir bar, wrap the glass bottle with aluminum foil, label it, and place it on a magnetic stirrer to stir in the dark for 4 hours until clear and transparent. This yields the photoresist composition, ready for use.

[0058] b) Prepare a rectangular glass coverslip with a thickness of 0.15 mm. Soak the coverslip in deionized water containing detergent for 30 minutes using ultrasonic cleaning. Repeat the ultrasonic cleaning process 6 times with deionized water, then dry it in an oven. Immerse the dried coverslip in a 5 wt% KH-570 / toluene solution for 2 hours, then quickly clean it with anhydrous ethanol and dry it.

[0059] c) The femtosecond laser processing system used in this invention is as shown in the appendix. Figure 1 As shown. The femtosecond laser wavelength is 780 nm, the objective lens magnification is 60x, and the numerical aperture is 1.42. The prepared photoresist composition is dropped onto a cleaned glass cover glass, which is then placed on the piezoelectric moving stage of the femtosecond laser processing system. Using a femtosecond laser power of 40 mW and a scanning speed of 40 μm / s, the designed square stage structure is fabricated. The laser movement path consists of continuous coordinates, which are generated by scaling the designed processing model using computer software to serve as the femtosecond laser processing path.

[0060] d) After processing, remove the glass cover glass from the piezoelectric stage and remove unreacted photoresist with ethanol. After the ethanol evaporates naturally, the designed microstructure with dual-response properties can be obtained, such as... Figure 3 As shown, it is a suspended square platform structure supported by a cylindrical structure with a diameter of 8μm, wherein the side length of the square platform structure is 32μm.

[0061] e) The processed square microstructure with a side length of 32 μm was placed in an aqueous solution. The aqueous solution was first slowly heated and then slowly cooled. The temperature response characteristics of the microstructure were observed, and the results are shown in [Figure number missing]. Figure 3 As the temperature rises to 80°C, the microstructure shrinks, with its length decreasing to 29 μm. However, when the temperature drops back to the initial temperature, the microstructure returns to its original size, fully demonstrating its temperature responsiveness.

[0062] Example 3

[0063] a) First, prepare a clean 5mL glass bottle with a cap. Add 0.53g of polyethylene glycol diacrylate, 0.15g of dimethylaminoethyl methacrylate, 0.01g of 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, 0.01g of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 0.3g of pentaerythritol triacrylate in sequence. Then add a clean magnetic stir bar, wrap the glass bottle with aluminum foil, label it, and place it on a magnetic stirrer to stir in the dark for 4 hours until clear and transparent. This yields the photoresist composition, ready for use.

[0064] b) Prepare a rectangular glass coverslip with a thickness of 0.15 mm. Soak the coverslip in deionized water containing detergent for 30 minutes using ultrasonic cleaning. Repeat the ultrasonic cleaning process 6 times with deionized water, then dry it in an oven. Immerse the dried coverslip in a 5 wt% KH-570 / toluene solution for 2 hours, then quickly clean it with anhydrous ethanol and dry it.

[0065] c) The femtosecond laser processing system used in this invention is as shown in the appendix. Figure 1 As shown. The femtosecond laser wavelength is 780 nm, the objective lens magnification is 60x, and the numerical aperture is 1.42. The prepared photoresist composition is dropped onto a cleaned glass cover glass, which is then placed on the piezoelectric stage of the femtosecond laser processing system. The femtosecond laser power range is 30 mW, and the scanning speed is 40 μm / s. The laser movement path consists of continuous coordinates; by adjusting the density of these continuous coordinates, microarm structures with asymmetric crosslinking density are fabricated.

[0066] d) After processing, remove the glass cover glass from the piezoelectric stage and remove unreacted photoresist with ethanol. After the ethanol evaporates naturally, the designed microstructure with dual-response properties can be obtained, such as... Figure 4 As shown, a microarm structure with asymmetric crosslinking density is presented. This microarm structure exhibits a pH response through bending angle, depending on the different responsiveness brought about by the crosslinking density.

[0067] e) The processed microarm structure was then placed in solutions prepared with dilute hydrochloric acid and sodium hydroxide, with pH values ​​of 1 and 13, and the pH response characteristics of the microarm structure were observed. The results are shown in [Figure number missing]. Figure 4 .Depend on Figure 4 The study found that after immersion in an acidic solution with pH=1, the hydrogel on the low-crosslinked side exhibited a greater swelling rate due to water absorption than the high-crosslinked side, and the microarm structure bent to the right. Conversely, when transferred from the acidic solution with pH=1 to an alkaline solution with pH=13, the hydrogel on the low-crosslinked side showed a greater shrinkage rate due to water loss than the high-crosslinked side, and the microarm structure bent to the left. This demonstrates a clear pH-responsiveness.

[0068] Example 4

[0069] a) First, prepare a clean 5mL glass bottle with a cap. Add 0.53g of polyethylene glycol diacrylate, 0.15g of dimethylaminoethyl methacrylate, 0.01g of 2,4,6-(trimethylbenzoyl)diphenylphosphine oxide, 0.01g of 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 0.3g of pentaerythritol triacrylate in sequence. Then add a clean magnetic stir bar, wrap the glass bottle with aluminum foil, label it, and place it on a magnetic stirrer to stir in the dark for 4 hours until clear and transparent. This yields the photoresist composition, ready for use.

[0070] b) Prepare a rectangular glass coverslip with a thickness of 0.15 mm. Soak the coverslip in deionized water containing detergent for 30 minutes using ultrasonic cleaning. Repeat the ultrasonic cleaning process 6 times with deionized water, then dry it in an oven. Immerse the dried coverslip in a 5 wt% KH-570 / toluene solution for 2 hours, then quickly clean it with anhydrous ethanol and dry it.

[0071] c) The femtosecond laser processing system used in this invention is as shown in the appendix. Figure 1 As shown. The femtosecond laser wavelength is 780 nm, the objective lens magnification is 60x, and the numerical aperture is 1.42. The prepared photoresist composition is dropped onto a cleaned glass cover glass, which is then placed on the piezoelectric stage of the femtosecond laser processing system. The femtosecond laser power range is 30 mW, and the scanning speed is 40 μm / s. The laser movement path consists of continuous coordinates; by adjusting the density of these continuous coordinates, microarm structures with asymmetric crosslinking density are fabricated.

[0072] d) After processing, remove the glass cover glass from the piezoelectric stage and remove unreacted photoresist with ethanol. After the ethanol evaporates naturally, the designed microstructure with dual-response properties can be obtained, such as... Figure 5 As shown, a microarm structure with asymmetric crosslinking density is presented. This microarm structure exhibits a temperature response through bending angle, depending on the different responsiveness brought about by the crosslinking density.

[0073] e) Place the fabricated microarm structure in an aqueous solution. The aqueous solution is first slowly heated and then slowly cooled. Observe the temperature response characteristics of the microstructure. The results are shown in [Figure number missing]. Figure 5 As the temperature rises to 80℃, the low-crosslinked hydrogel exhibits a greater shrinkage rate due to water loss than the high-crosslinked side, causing the microarm structure to bend to the left. However, when the temperature drops back to its initial value, the low-crosslinked hydrogel shows a greater swelling rate due to water absorption than the high-crosslinked side, causing the microarm structure to bend to the right. This fully demonstrates its temperature responsiveness.

[0074] The photoresist composition prepared by the application can be quickly formed in a femtosecond laser irradiation area, and a complex three-dimensional microstructure with high resolution is obtained; the obtained microstructure does not need to add additional substances, and can realize stable and repeatable temperature response and pH response behaviors.

[0075] Obviously, the above embodiments of the application are only examples for clearly illustrating the application, and are not intended to limit the implementation manners of the application; for ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description, and it is impossible to enumerate all the implementation manners here; any changes or variations derived from the technical solutions of the application still fall within the protection scope of the application.

Claims

1. Use of a photoresist composition in the manufacture of a microstructure with dual response, characterized in that, The photoresist composition comprises a functional monomer, a photoinitiator and a polymer; The functional monomer is selected from polyethylene glycol diacrylate and dimethylaminoethyl methacrylate; The photoinitiator is selected from 2-hydroxy-2-methyl-1-phenyl-1-propanone and 2,4,6 (trimethylbenzoyl) diphenyl phosphine oxide; The polymer is selected from pentaerythritol triacrylate; The specific steps for preparing the microstructure are as follows: (1) mixing the functional monomer, the photoinitiator and the polymer in a brown glass container in a yellow light darkroom according to the proportion, and stirring to obtain a photoresist composition; (2) dropping the photoresist composition on a substrate, and irradiating the photoresist composition with a femtosecond laser; (3) developing the irradiated photoresist composition in a developing solution to obtain a double-response microstructure; The laser moving path is composed of continuous coordinates, and by adjusting the density of the continuous coordinates, a micro-arm structure with asymmetric crosslinking density is prepared.

2. Use according to claim 1, characterized in that, The substrate is selected from glass sheet, silicon sheet, flexible resin film, quartz sheet, sapphire or conductive glass ITO.

3. Use according to claim 1, characterized in that, The wavelength of the femtosecond laser is 200-1100 nm; the femtosecond laser power range is 5-40 mW; and the scanning speed range is 5-100 μm / s.

4. Use according to claim 1, characterized in that, The photoresist composition comprises 5-95 parts of the functional monomer, 5-80 parts of the polymer and 0.01-20 parts of the photoinitiator.

5. The use according to claim 1, characterized in that, The photoresist composition comprises 10-50 parts of the functional monomer, 10-60 parts of the polymer and 0.01-10 parts of the photoinitiator.

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