CN113461851B

CN113461851B - Application of polymer and photoresist containing polymer

Info

Publication number: CN113461851B
Application number: CN202110653466.1A
Authority: CN
Inventors: 罗亮; 田斯丹; 乐强; 孟凡玲
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2021-06-11
Filing date: 2021-06-11
Publication date: 2022-05-20
Anticipated expiration: 2041-06-11
Also published as: CN113461851A

Abstract

The invention relates to application of a polymer and a photoresist containing the polymer, belonging to the field of environment-friendly materials. Application of the polymer as degradable materialThe polymer contains a plurality of repeating units, and the structural formula of the repeating units is shown as the formula I:

and (3) subjecting the polymer to light and oxygen to carry out photooxidation degradation on the polymer into oligomer or dicarboxylic acid. The polymer in the invention can greatly reduce the molecular weight of the polymer and reduce the burden on the environment.

Description

Application of polymer and photoresist containing polymer

Technical Field

The invention relates to the field of environment-friendly materials, in particular to application of a polymer and a photoresist containing the polymer, and particularly relates to application of a degradable polymer and an article containing the polymer.

Background

The polymer material is widely applied to daily life. Wherein, the accumulation of the used polymer materials causes pollution to the environment and threatens the living health of human beings. Among them, the polymer plastic materials synthesized from petroleum are mostly inert in natural environment, and the natural degradation process may last centuries after being discarded.

Currently, a class of biodegradable polymer plastics has been synthesized. Such plastics can be degraded in laboratory or industrial composting environments. However, the recovery and degradation of such plastics require various processes from collection, classification, to incineration, and the like, which require a large amount of labor and material costs. On the other hand, the recycling environment is severe, the degradation catalyst is expensive, and the performance of the recycled product is deteriorated, which are factors restricting the development of the catalyst.

In fact, the current situation is that most plastics are still wasted in all corners of the earth and cannot be recycled. The main chain of the polysuccinyne forms a conjugated structure by C ═ C and C ≡ C bonds, and the polysuccinyne has been widely researched in the fields of optoelectronic communication, light-emitting diodes, electronic sensors and the like. Nowadays, internet science and technology is developed at a high speed, electronic products are updated rapidly, and a great amount of high-molecular conjugated polymers are contained in waste electronic devices. Degradable conjugated polymers are very rare and degradation and recycling of conjugated polymers after consumption is more challenging than commercial plastics.

In order to solve the problems, the invention aims to provide the application of the polydiacetylene with a specific structure in preparing degradable materials, which can greatly reduce the molecular weight of the polymer and reduce the burden on the environment under certain conditions.

Disclosure of Invention

The invention solves the problem that the high molecular conjugated polymer in the prior art is difficult to degrade, provides the application of the polydiacetylene conjugated polymer with a specific structure in preparing degradable materials, can greatly reduce the molecular weight of the polymer under certain conditions, and reduces the burden on the environment.

According to a first aspect of the present invention, there is provided a use of a polymer as a degradable material, the polymer comprising a plurality of repeating units, the repeating units having a formula as shown in formula i:

preferably, the polymer is subjected to light and in the presence of oxygen to photooxidatively degrade the polymer into oligomers and/or dicarboxylic acids.

Preferably, the oxygen-existing condition is an oxygen-existing condition or an active oxygen-existing condition.

Preferably, the oligomer has a weight average molecular weight of less than 5000, or the oligomer has a weight average molecular weight of 20% or less of the weight average molecular weight of the polymer.

Preferably, the dicarboxylic acid has the formula HOOC- (CH)₂) n-COOH, wherein n is less than or equal to 6 and n is a positive integer;

the dicarboxylic acid accounts for more than 10 wt%, preferably more than 20 wt%, and more preferably more than 40 wt% of the degradation product.

Preferably, the illumination is at least one of natural light, green light or blue light;

the photooxidative degradation process is added with a photosensitizer and/or the photooxidative degradation process is carried out in the presence of water.

Preferably, the weight average molecular weight of the polymer is from 1 to 1000 ten thousand.

According to another aspect of the present invention, there is provided a use of a polymer for the preparation of a no-clean photoresist, the polymer comprising a plurality of repeating units, the repeating units having a formula as shown in formula I:

According to another aspect of the present invention, there is provided a clean-free photoresist comprising a polymer comprising a plurality of repeating units, wherein the repeating units have a structural formula shown in formula I:

generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

(1) the invention realizes the degradation of the waste conjugated polymer by utilizing natural conditions, thereby avoiding the high-cost waste recovery process.

(2) The degradation process of the invention does not need additional energy input to avoid secondary pollution.

(3) The main chain of the polymer molecule of the invention is completely broken through chemical reaction.

(4) The degradation product is green and environment-friendly, and the degradation strategy is widely suitable for conjugated polymer molecules containing conjugated unsaturated main chain structures.

(5) The polymer of the invention is used as a photoresist material degradation product and is small molecule, and can realize larger difference of physicochemical properties.

(6) The degradation product of the invention is easy to sublimate, and the dry development of the photoresist can be realized.

Drawings

FIG. 1 is a trace of the PDDA film preparation and degradation in example 1: wherein A is a scheme for synthesizing PDDA by topochemical polymerization, and a photograph of a PDDA film prepared by a solution casting method. B is a photograph of the PDDA film immersed in fresh water or seawater, which is left standing outdoors and gradually degraded by natural light.

FIG. 2 is a photograph of agarose gel electrophoresis of a PDDA solid dispersion of example 1 after exposure to 800W LED white light for various periods of time.

FIG. 3 is a quantitative analysis of color signal intensity in the electrophotograph of FIG. 2 using the software "ImageJ 1.51J 8" in example 1 to show the change of Molecular Weight (MW) of PDDA with white light irradiation time.

FIG. 4 is a representation of the complete degradation of the PDDA Microparticles (MPs) in the natural environment of example 2: wherein A is a photograph of a deionized water dispersion of PDDA MPs exposed to natural light in the open air environment of Wuhan City for various periods of time. And B is positive and negative photoetching photo patterns generated by photoetching under the irradiation of ambient natural light after the PDDA film deposited on the filter paper covers the mask. C is the change of the absorption spectrum of the deionized water dispersion of the PDDA MPs along with the prolonging of the natural light irradiation time. The inset to the C is the absorbance at 500nm of a deionized water dispersion of PDDA MPs (A)₅₀₀) Changes with the prolonged time of natural light irradiation. D is the change of the Raman spectrum of the deionized water dispersion of the PDDA MPs along with the prolonging of the natural light irradiation time. The inset of the D is the deionized water dispersion of PDDA MPs at 1522cm^-1(I₁₅₂₂) And 2121cm^-1(I₂₁₂₁) The relative raman intensity of (a) changes with the natural illumination time.

FIG. 5 is a characterization of the degradation products in example 3: wherein A is the NMR spectrum of a crude product of PDDA degradation in natural ambient light, PDDA and succinic acid (succinic acid) standards. B is the nuclear magnetic resonance carbon spectrum of a crude product of PDDA degradation in natural environment illumination, PDDA and a succinic acid standard. And C is a high-resolution mass spectrum of a crude product and a succinic acid standard product of PDDA degradation in natural environment illumination. And D is a high performance liquid chromatography-mass spectrometry combined analysis chart of a crude product of PDDA degradation in natural environment illumination and a succinic acid standard substance.

FIG. 6 is a characterization of the PDDA natural light photo-oxidative degradation mechanism in example 4: wherein A is a proposed backbone polydiacetylene backbone C atom¹³PDDA (PDDA-¹³C) Schematic diagram of the degradation mechanism of (1). B is PDDA-¹³C degrading the crude product by natural light photooxidationAfter the liquid chromatography-mass spectrometry combined analysis: alpha-ketoglutaric acid-¹³C₂(left panel) and succinic acid-¹³High performance liquid chromatography of C (right panel); the interpolation graphs are respectively: alpha-ketoglutaric acid-¹³C₂(left panel) and succinic acid-¹³High resolution mass spectrum (M) of C (right panel)^-). C is the in-situ nmr hydrogen spectrum of the PDDA film after standing in deuterated water and being exposed to dark and air for 5 days (air only), or to sunlight and nitrogen for 5 days (h v only), or to sunlight and air for 5 days (air + h v). D is PDDA-¹³The LC-MS spectrum of the crude product of C degradation also shows a sharp 118.0215m/z peak corresponding to the expected 1¹³C atom-labeled succinic acid m/z signal (m/z 118.0227,¹³CC₃H₅O₅ M^-) Consistent, it is demonstrated that the PDDA photooxidative degradation process undergoes decarboxylation of alpha-ketoglutarate to succinic acid.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The raw material sources used in the invention are as follows: sodium hydroxide (NaOH), hydrochloric acid (HCl), sodium chloride, acetic acid, formic acid were purchased from pharmaceutical chemicals, Inc. Malonic acid, malic acid, Succinic Acid (SA) were purchased from shanghai alatin biochemical technologies, ltd. Alpha-ketoglutaric acid was purchased from bio-medicine technologies, limited, Haohnhong, Shanghai. Fe₃O₄Nanoparticles were purchased from shanghai yan chemical technology limited. Deuterated solvents were purchased from Cambridge Isotope Laboratories, inc. Chromatographic grade acetonitrile was purchased from Fisher corporation. (trimethylsilyl) acetylene-13C 2 was purchased from Sigma-Aldrich (Shanghai) trade, Inc. 4-Pentyyn-1-ol, Methylene Blue (MB) and Rose Bengal (RB) were all purchased from Annaiji chemical company. Other reagents and solvents were purchased from the national pharmacyChemical reagents, Inc., and used as received.

The polydiacetylene conjugated polymer with the specific structure has excellent degradability, does not depend on the conditions generally required by the existing biodegradable materials such as specific microorganisms, enzymes, temperature, pH and the like, can be rapidly degraded in natural environment such as seawater or refuse landfill, and does not leave fragments or harmful substances.

The invention provides an application of a polymer as a degradable material, wherein the polymer contains a plurality of repeating units, and the structural formula of the repeating units is shown as a formula I:

the polymer in the invention is synthesized by adopting eutectic supports for topological chemical polymerization.

The number of carbon atoms between the double bond of the main chain of the polymer of the invention and the carboxyl group is from 1 to 6 as shown in the figure, preferably from 1 to 4 or from 1 to 3, most preferably 2.

The weight average molecular weight of the polymer of the present invention is 1W to 1000W, preferably 1W to 50W or 1W to 20W or 1W to 10W, more preferably 2W to 8W or 4W to 7W.

The weight average molecular weight of the chain segment of the repeating unit in the formula I is less than or equal to the weight average molecular weight of the polymer. The recurring units of formula I represent more than 50% by weight, preferably 70% by weight and more preferably 90% by weight of the polymer.

The weight average molecular weight of the segment of the repeating unit of the formula I is 1W to 100W, preferably 1W to 50W or 1W to 20W or 1W to 10W, more preferably 2W to 8W or 4W to 7W.

The degradation process of the polymer of the invention comprises carrying out in the presence of light. The light presence condition may be natural light, green light or blue off, preferably natural light.

The degradation process of the polymer of the invention comprises carrying out it in the presence of oxygen. The oxygen may be present in air, enriched air, or with the addition of oxygen, or pure oxygen. Preferably air or externally applied oxygen, more preferably air.

The degradation process of the polymer can be carried out under the condition of adding a photosensitizer, or the photosensitizer is not added. The photosensitizer is a conventional photosensitizer known in the art.

The degradation process of the polymer of the invention can be carried out in the presence of water. The water conditions include pure water, tap water, fresh water from the natural environment, or seawater.

The degradation process of the polymer of the invention comprises carrying out under certain temperature conditions. The certain temperature is-40-100 ℃, preferably-40-50 ℃, 0-40 ℃ or 20-30 ℃ close to room temperature, and more preferably about 25 ℃.

As the main chain of the polymer is broken in the degradation process of the polymer chain segment of the repeating unit in the formula I, the molecular weight of the polymer is greatly reduced after the polymer is degraded, and the burden on the environment and the recovered or treated materials is reduced. The degradation process time is 0.1-60 days, preferably 0.5-30 days or 1-15 days, more preferably 2-10 days, most preferably 3-6 days.

The mass spectrum molecular weight of the degraded polymer is below 5000, or below 3000, preferably below 2000, and more preferably below 1000. When the molecular weight of the polymer is degraded to below 1000, the high molecules are basically and completely eliminated, and the product is full small molecules, so that zero burden is realized on the environment.

When the molecular weight of the polymer in a specific application scene is larger, such as the weight average molecular weight of the polymer is more than 10W, 20W, or 50W, the molecular weight of the polymer can be greatly reduced through the degradation process, and a degradation product with the mass spectrum molecular weight of less than 20% or less than 10%, preferably less than 8%, and more preferably less than 5% of the weight average molecular weight of the polymer is obtained.

Degradation products of the polymer include dicarboxylic acids: HOOC- (CH)₂)_n-COOH, n being as defined for the number of carbon atoms between the double bond of the polymer main chain and the carboxyl group. Preferably, succinic acid is included in the degradation products of the polymer.

The content of dicarboxylic acid in the degradation product is more than 10 wt%, preferably more than 20 wt%, and more preferably more than 40 wt%.

Due to the good degradation performance of the polymer, the polymer can be used in the fields of materials such as optics, electrics, engineering plastics and the like. Degradable materials include photoresists or electronic devices such as conductive elements, LEDs, sensors, etc.

When the polymer is used as the photoresist, the photoresist layer formed by the polymer is subjected to pattern etching under the conditions of illumination and oxygen, the etching part is degraded, the cleaning step is omitted, the polymer is a substantially clean-free photoresist, and the problem of reduced pattern quality caused by the cleaning of the traditional photoresist by a solvent is solved.

The invention also provides a photoresist comprising the aforementioned polymer and at least one additive that does not need to be removed after the photolithography process. The particular type of additive may be selected as required by the actual lithographic process.

In some embodiments, the polymer comprises a plurality of repeating units having a formula as shown in formula II:

in some embodiments, the recurring unit of formula II comprises more than 50 wt%, preferably 70 wt%, more preferably 90 wt% of the polymer.

In some embodiments, the degradation of the chain segments of the repeating units of formula ii results in a mass spectrum having a molecular weight in the range: degradation products of 3000 or less, preferably 2000 or less, more preferably 1000 or less.

In some embodiments, the degradation of the chain segments of the repeating units of formula ii results in a mass spectrum having a molecular weight in the range: a degradation product of 10% or less, preferably 8% or less, more preferably 5% or less of the weight average molecular weight of the polymer.

Example 1: preparation of PDDA film and complete degradation in natural environment

(1) Synthesis of Polymer PDDA

The PDDA is synthesized by performing topochemical polymerization on a host and an object by using deca-4, 6-diynedic acid (DDA) as a raw material and using an object N, N' -bis (pyridine-4-ylmethyi) ethane diamide as a eutectic support (A in figure 1).

(2) Preparation of PDDA film

PDDA films were prepared by solution casting: the PDDA is precipitated on the nylon membrane by deionized water, methanol, ethanol or other common low-boiling point solvents, and is peeled off from the nylon membrane after being dried. The PDDA film is dark red and exhibits a highly pi-conjugated skeletal character (a in fig. 1). The PDDA film keeps stable in property under the dark or nitrogen condition, and good stability of the PDDA film as a functional material is ensured.

(3) PDDA is completely degraded in natural environment

In the embodiment, three elements of 'natural light, water and air' are used for simulating a common natural environment, fresh water (standard deionized water) and seawater (yellow sea water near a hong Kong) are respectively selected, and experiments are carried out in natural light and air in outdoor clear weather of Wuhan city in 6-12 months. The PDDA film was immersed in fresh or sea water, left on an outdoor stand exposed to natural light and air, rapidly broken down into small pieces within 2 days, and finally the solids completely disappeared within one week, and the aqueous solution remained colorless, indicating that the PDDA was completely degraded at the molecular level (B in fig. 1).

(4) Electrophoresis tracing PDDA molecular level molecular weight change

An LED white light lamp (800W) is used as a stable light source. And analyzing the PDDA solid dispersion liquid sample before and after the LED white light is continuously irradiated for different time by adopting a gel electrophoresis method, and tracking the molecular weight change of the PDDA solid in the degradation process. Electrophoresis results as shown in fig. 2 and 3: the molecular weight of the original PDDA is more than 650kD through the correction of DNA marker marks with standard molecular weight; irradiating the PDDA sample for 1h by using white light, and enabling the color band corresponding to the high molecular weight to disappear; the signal of PDDA shifts significantly to the low molecular weight region as the illumination time is extended; the molecular weight of the PDDA is continuously reduced along with the prolonging of the illumination time, and the molecular weight is reduced to below 6.5kD after illumination for 6 hours; after 12h of illumination, no polymer bands were visible on the gel electrophoresis. After 96h of illumination, no PDDA signal is collected by gel electrophoresis, which indicates that PDDA is completely degraded into colorless small molecules. In addition, the shear viscosity of the PDDA solutions of different concentrations (pH 8.0) after irradiation also decreased significantly and no longer exhibited the characteristics of the high molecular weight polymer.

Example 2: PDDA microparticles are completely degraded in natural environment

(1) The color and tyndall dispersion effect of the PDDA microparticle dispersion completely disappear in natural illumination

Of particular concern in plastic contamination is plastic microparticles that may enter the natural ecosystem from a variety of sources and eventually accumulate in the food chain. The present invention also measures the degradability of PDDA Microparticles (MPs) in order to ensure that no micro-plastic build-up occurs during the PDDA fragmentation and degradation process. As shown in a of fig. 4, the red color and tyndall scattering effect of the dispersion of PDDA MPs rapidly disappeared within 30 minutes when exposed to outdoor natural light; the color of the dispersion and the tyndall scattering effect remained unchanged after the same storage time in the dark. The dynamic light scattering measurement of the laser light scattering intensity of the PDDA MPs is reduced, and further proves that the PDDA MPs can be rapidly and completely decomposed into soluble small molecules under the irradiation of natural light, and no particles with the nanometer scale or above or insoluble polymer residues exist.

(2) Spectral change of PDDA (poly (propylene-co-butylene) microparticle dispersion liquid in natural environment

To study the changes in the molecular structure of PDDA in the natural environment, we monitored the absorption and raman spectral changes of PDDA MPs dispersions. The absorption spectrum results of the PDDA MPs dispersion show: the absorption peak decreased with increasing time of natural light irradiation (C in fig. 4), indicating that the conjugated main chain length thereof gradually decreased; by comparison, the absorption peaks of the PDDA MPs dispersion remained unchanged under dark conditions. In the corresponding raman spectra of PDDA MPs dispersion samples: raman characteristic peak on PDDA conjugated main chain "carbon-carbon double bond (C ═ C,1522 cm)^-1) And triple bonds (C.ident.C, 2121 cm)^-1) "the peak intensity decreased synchronously with the increase of the natural light irradiation time (D in FIG. 4), which proves that the carbon-carbon double bonds and triple bonds on the conjugated main chain of PDDA were completely consumed simultaneously during the light irradiation. The above data clearly show that the polymer conjugated backbone of PDDA can be completely decomposed by sunlight in air.

Example 3: characterization of PDDA degradation products

After the PDDA film or the solid dispersion liquid is illuminated for one week in the outdoor natural environment, the degradation mixed crude product is not dividedSeparating and purifying, freeze-drying, dissolving with deuterated water again, adjusting pH to 8 with NaOH, and performing nuclear magnetic resonance hydrogen spectrum, nuclear magnetic resonance carbon spectrum, high resolution mass spectrum, and high performance liquid chromatography-mass spectrum combined detection. As shown in a in fig. 5, there is no residual PDDA signal peak on the nmr hydrogen spectrum of the crude product, but a sharp single peak of 2.41ppm appears, which is consistent with the nmr hydrogen spectrum of the small molecule succinic acid. As shown in fig. 5B, the nmr carbon spectrum of the crude product also coincided with that of succinic acid, and the peaks associated with sp and sp2 carbons of PDDA disappeared accordingly, indicating that all C ═ C and C ≡ C bonds in the main chain have been cleaved. As shown by C in FIG. 5, high resolution mass spectrometry showed that the major component in the crude product was succinic acid (m/z 117.0181, C)₄H₅O₄M^-). As shown in D in fig. 5, hplc-ms analysis further confirmed that the main component in the crude product was succinic acid. The yield of succinic acid in the crude product is close to 50% by the analysis of hydrogen nuclear magnetic resonance spectrum. High performance liquid chromatography-mass spectrometry analysis also shows that a series of other dicarboxylic acid micromolecules which are not succinic acid can be generated in the PDDA degradation process, and each other dicarboxylic acid micromolecule is only trace. Most importantly, no m/z peak above 300 was found in high resolution mass spectrometry, which again confirms that PDDA has been completely degraded into small molecules.

Example 4: verification of PDDA photo-oxidative degradation mechanism

(1) Isotope of carbon monoxide¹³C-labeled PDDA conjugated main chain tracing degradation mechanism

According to the change of the molecular structure of PDDA in the degradation process: complete disappearance of C ═ C and C ≡ C bonds in the PDDA backbone; and characterization of the product: generating succinic acid; we propose a mechanism by which PDDA undergoes photo-oxidative degradation under natural light (sunlight, white light) irradiation in the air, as shown by a in fig. 6. According to this mechanism, the conjugated C ═ C and C ≡ C bonds in the PDDA backbone are completely oxidatively cleaved to produce α -ketoglutarate, a key intermediate, which is further decarboxylated and oxidized to produce succinic acid (a in fig. 6), the final product. In fact, we have analyzed in the crude degradation of PDDA by liquid chromatography-mass spectrometryThe trace amount of alpha-ketoglutaric acid (m/z145.0131, C) was identified₅H₅O₅ M^-). To further validate, we used all carbons on the conjugated backbone chain¹³C-labeled PDDA (PDDA-¹³C) The corresponding degradation intermediates and end products are traced. As can be seen from LC-MS, PDDA-¹³The crude degradation product of C contained a sharp m/z signal peak of 147.0189 (C in FIG. 6), corresponding to the expected 2¹³C atom-labeled alpha-ketoglutarate m/z signal (m/z 147.0210,¹³C₂C₃H₅O₅ M^-) Are consistent and not all are collected¹²Alpha-ketoglutaric acid of C (m/z 145.0132, C)₅H₅O₅ M^-) The complete oxidative cleavage of the PDDA backbone C ═ C and C ≡ C bonds to α -carbonyl carboxylic acid structures is demonstrated. In addition, PDDA-¹³The LC-MS spectrum of the crude product of C degradation also shows a sharp 118.0215m/z peak corresponding to the expected 1¹³C atom-labeled succinic acid m/z signal (m/z 118.0227,¹³CC₃H₅O₅ M^-) In agreement, it was demonstrated that the PDDA photo-oxidative degradation process underwent decarboxylation of α -ketoglutarate to succinate (D in fig. 6).

(2) PDDA is completely oxidatively degraded by active oxygen generated by various ways

PDDA can also be completely decomposed by Reactive Oxygen Species (ROS) generated by Fenton's reagent or photosensitizer under proper light irradiation, and succinic acid is still the major decomposition product, demonstrating that PDDA can be completely oxidatively degraded by reactive oxygen species generated in a variety of ways. It is shown that PDDA can be degraded by ROS produced by various pathways in the natural environment, such as microorganisms, enzymes, photosensitizers, peroxides, and the like.

(3) The photooxidation degradation of PDDA in natural environment depends on the coexistence of oxygen and light

In order to prove that the PDDA photooxidative degradation process needs to be performed by oxygen and light simultaneously, the PDDA film is placed in deuterium water sealed with air in the dark for 5 days, or in deuterium water sealed with nitrogen in natural light for 5 days, and the in-situ nmr spectrogram shows no nuclear magnetic signal of succinic acid (B in fig. 6). The PDDA film produced a sharp succinic acid nuclear magnetic signal after being placed in deuterium water sealed in air under natural light for 5 days, further confirming that the photo-oxidative degradation characteristic of PDDA degradation requires the simultaneous participation of oxygen and light (B in fig. 6).

(4) Change of organic carbon during PDDA degradation

The total organic carbon measurement shows that the content of organic carbon of PDDA after natural photooxidation degradation is reduced by about 20 percent, and is matched with the carbon loss in the degradation process of the degradation mechanism degradation polymer provided in A in figure 6. The fact that 80% of the carbon atoms and oxygen atoms trapped from the atmosphere in PDDA are preserved in the degradation products, as shown in a in figure 6, indicates the excellent atomic economic prospects of this upgrading cycle.

Example 5: PDDA lithographic pattern

In addition, after the filter paper coated with the PDDA is covered with different photomasks and exposed to natural environment illumination, the filter paper is etched by natural light (sunlight) within a few minutes to form a picture with good resolution (B in fig. 4), and the efficient decomposition of the PDDA MPs under sunlight illumination is also confirmed. A PDDA aqueous solution (10mg/mL) is spin-coated on a silicon wafer at the rotating speed of 1500rpm to form a thin film with the thickness of about 0.1-1um, and a line pattern with the width of 1um is successfully and completely etched by a laser with the power of 50mW and the wavelength of 488nm, which indicates that the PDDA can be prepared into a photoresist.

Pro-oxidant containing materials have been used to prepare oxidatively degradable plastics. However, whether these plastics can be completely mineralized or degraded into acceptable products in the natural environment remains a great problem. In contrast, the case of conjugated polymers is completely different. Since the conjugated polymer has a conjugated pi-electron skeleton, photochemical generation of active oxygen can be significantly promoted. Therefore, photo-oxidation has great promise in degrading the unsaturated conjugated backbone of the conjugated polymer by photo-oxidation without any co-oxidant. In fact, we observed similar photo-oxidative degradation reactions on model small molecules conjugated with C ═ C and C ≡ C bonds and generated succinic acid, which suggests that the photo-oxidative reaction can proceed exhaustively on polymers and fragmented analogs with conjugated repeating units of C ≡ C and C ≡ C bonds. Thus, in addition to representing the pioneer paradigm for environmentally degradable conjugated polymers, PDDA is completely degraded in air by natural light (sunlight) into green upgraded cycle products, also validating a promising general strategy for degrading post-consumer conjugated polymers in natural environments.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. The application of a polymer as a degradable material, wherein the polymer comprises a plurality of repeating units, and the structural formula of each repeating unit is shown as the formula I:

subjecting the polymer to light and oxygen to cause the polymer to undergo photooxidative degradation into oligomers and/or dicarboxylic acids; the weight average molecular weight of the oligomer is less than 5000, or the weight average molecular weight of the oligomer is less than 20% of the weight average molecular weight of the polymer;

the oxygen existence condition is an oxygen existence condition, and the illumination is at least one of natural light, green light or blue light.

2. Use of the polymer of claim 1 as a degradable material, wherein the dicarboxylic acid has the formula HOOC- (CH)₂) n-COOH, wherein n is less than or equal to 6 and n is a positive integer; the dicarboxylic acid accounts for more than 10 wt% of the degradation product.

3. Use of a polymer according to claim 2 as a degradable material, wherein the dicarboxylic acid comprises more than 20 wt% of the degradation product.

4. Use of a polymer according to claim 2 as a degradable material, wherein the dicarboxylic acid constitutes more than 40 wt% of the degradation products.

5. Use of a polymer according to claim 1 as a degradable material, wherein the photooxidative degradation process is carried out in the presence of water.

6. Use of a polymer according to claim 1 as a degradable material, wherein the weight average molecular weight of the polymer is from 1 to 1000 ten thousand.

7. The application of a polymer in preparing a wash-free photoresist comprises a plurality of repeating units, wherein the structural formula of the repeating units is shown as a formula I:

8. Use of a polymer according to claim 7 for the preparation of a photoresist, wherein the polymer has a weight average molecular weight of from 1 to 1000 ten thousand.