CN114395233B

CN114395233B - Degradable plastic and preparation method thereof

Info

Publication number: CN114395233B
Application number: CN202210115591.1A
Authority: CN
Inventors: 牛志强; 张胜波; 吴艳芬
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2022-02-07
Filing date: 2022-02-07
Publication date: 2022-10-25
Anticipated expiration: 2042-02-07
Also published as: CN114395233A

Abstract

The invention discloses degradable plastic and a preparation method thereof. The invention adds the bimetallic complex catalyst as an additive into polyester or polyamide plastics, thereby providing possibility for realizing the degradation of plastics in natural environments such as oceans and the like, the degradation of plastics under the condition of composting and accelerating the degradation of mulching films. Compared with a biological enzyme catalyst, the added bimetallic ligand catalyst is more stable; the catalyst has wider operable range when being mutually soluble with plastics compared with a biological enzyme catalyst; compared with a biological enzyme catalyst, the binuclear metal ligand catalyst can be suitable for various polyester or polyamide plastics, and breaks through the specificity limitation of the traditional biological enzyme catalyst.

Description

Degradable plastic and preparation method thereof

Technical Field

The invention relates to the field of polyester and polyamide plastics, in particular to degradable plastic and a preparation method thereof.

Background

In recent years, the use of plastics in large quantities has created serious environmental and energy problems. It normally takes decades or even hundreds of years for waste plastics to naturally degrade in the environment, such as the ocean. Therefore, how to accelerate the natural degradation process of waste plastics is a great challenge. Among them, the acceleration of plastics degradation by means of sea water, compost and other conditions by adding a bio-enzyme catalyst in the plastics synthesis process in an additive manner is a very potential plastics treatment approach. In addition, the degradable plastic product containing the catalyst also provides possibility for accelerating the degradation of the mulching film in the farmland.

The biological enzyme catalyzes the degradation of polyester plastics to be a mild and environment-friendly effective mode, but the activity of the biological enzyme is excessively dependent on temperature and pH value, the external pollution resistance is poor, and the biological enzyme is easy to inactivate in the presence of additives or pigments, so that the biological enzyme hardly plays a catalytic role in a complex ecological environment. Therefore, the development of novel degradable plastic products and the acceleration of the degradation of traditional polyester and polyamide plastics in natural environment (such as seawater), the degradation under composting condition and the degradation of mulching films in agricultural fields by means of plastic additives are problems to be solved urgently.

Disclosure of Invention

The invention aims to provide degradable plastic, which is characterized in that a bimetallic complex catalyst is added into a plastic product in a plastic additive mode, so that the degradation of various polyester and polyamide plastics is catalyzed under the conditions of seawater, compost and the like, and the degradation of mulching films in farmlands is accelerated.

The invention also aims to provide a preparation method of the degradable plastic.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a degradable plastic, which comprises a catalyst for catalyzing the degradation of the plastic, wherein the catalyst is a bimetallic complex.

The bimetallic complex can catalyze plastics to degrade into monomers, and the bimetallic complex is directly added into a plastic product as an additive, so that the bimetallic complex exists relatively stably in the plastic product, and can realize the degradation of the plastics in natural environments such as seawater and the like and under the condition of plastic composting and accelerate the degradation of mulching films.

According to the degradable plastic of the present invention, preferably, the bimetallic complex is selected from compounds represented by the following structural general formula 1, formula 2, formula 3 or formula 4:

wherein, M ₁ And M ₂ Represents a metal atom independently selected from transition metals such as Fe, co, ni, cu, zn, mg, ca, mn, ru, pd or Pt, and M ₁ And M ₂ Between two atoms of

M ₁ And M ₂ May be the same or different;

Y ^n- selected from NO ₃ ^– 、Cl ^– 、Br ^– 、OAc ^– 、ClO ₄ ^– 、OH ^– Or SO ₄ ^2– Plasma anions;

R ₃ independently selected from H, hydrocarbyl, halogen, hydroxy or carboxy, or R ₃ And R ₁ Or R ₁ ' fused to form a ring;

R ₄ selected from H, hydrocarbyl, halogen, hydroxyl, carboxyl, nitro, methoxy or ether-containing groups.

According to the degradable plastic of the invention, preferably, the hydrocarbon group comprises a C1-C6 alkyl group, such as a C1-C4 alkyl group.

According to the degradable plastic of the invention, preferably, the structure of the bimetallic complex is as follows:

the degradable plastic according to the present invention is preferably a polyester plastic or a polyamide plastic, wherein the polyester includes but is not limited to carboxylate, carbonate, phosphate.

More preferably, the polyester or polyamide plastic is selected from one or a combination of two or more of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polylactic acid (PLA), polycaprolactone (PCL), polybutylene adipate/terephthalate (PBAT), polycarbonate (PC), polyurethane (TPU), polyethylene 2, 5-furandicarboxylate (PEF), polybutylene succinate (PBS), polybutylene adipate (PBA), poly-3-hydroxybutyrate (PHB) and poly (3-hydroxybutyrate-4-hydroxybutyrate) (P3/4 HB), nylon 66.

The degradable plastic according to the present invention preferably the bimetallic complex is 0.05wt.% to 20wt.%, more preferably 1.5wt.% to 20wt.% of the polyester or polyamide plastic.

In another aspect, the present invention provides a method for preparing one or more degradable plastics, which includes, but is not limited to, the following methods:

the method comprises the following steps: dissolving polyester or polyamide plastic and a bimetallic complex in an organic solvent, and then removing the solvent to obtain degradable plastic containing the bimetallic complex;

the method 2 comprises the following steps: melting polyester or polyamide plastics and a bimetallic complex at high temperature, and then molding and extruding to obtain degradable plastics containing the bimetallic complex;

the method 3 comprises the following steps: mixing polyester or polyamide plastic and a bimetallic complex and fully ball-milling to obtain degradable plastic containing the bimetallic complex;

the method 4 comprises the following steps: the polyester or polyamide plastic is smashed into fine particles, then the fine particles are soaked in the aqueous solution containing the bimetallic complex, the plastic particles fully adsorb the bimetallic complex, and finally the solid mixture is separated out and extruded and molded to obtain the degradable plastic containing the bimetallic complex.

In the above method 1, preferably, the organic solvent is selected from one or a combination of two or more of dichloromethane, toluene, chloroform, hexafluoroisopropanol, m-cresol, tetrahydrofuran and N, N-dimethylformamide.

In the above method 2, preferably, the temperature of the high-temperature melting and shaping extrusion is 180 to 300 ℃;

in the above method 4, preferably, the mesh number of the polyester or polyamide plastic crushed into fine particles is 800-1500 meshes.

According to the preparation method of the present invention, preferably, the bimetallic complex is 0.05wt.% to 20wt.%, more preferably 1.5wt.% to 20wt.% of the polyester or polyamide plastic.

In the examples of the present invention, in order to test the degradation effect of the degradable plastic of the present invention, the plastic was placed in an alkaline aqueous solution selected from, but not limited to, 10 and heated for hydrolysis ^-7 KOH solution of M to 1.0M, 10 ^-7 NaOH solution of M to 1.0M, 10 ^-7 M1.0M Ca (OH) ₂ And (3) solution. More preferably, the concentration of the aqueous alkaline solution is less than 10 ^-3 M, e.g. 10 ^-7 M～10 ^-3 M; the alkaline aqueous solution is selected from but not limited to 10 ^-7 M～10 ^-3 NaOH solution of M. In a specific embodiment of the present invention, the temperature of the hydrolysis reaction is preferably 25 ℃ to 60 ℃ (30 ℃ to 50 ℃); the time for the hydrolysis reaction is preferably 0.5 to 30 days, for example, 2 to 15 days, 15 to 30 days, or the like.

In order to further test the degradation effect of the degradable plastic in the environment, tests are carried out under the conditions of seawater and compost in the embodiment, the plastic is made into a film to replace a mulching film, and the degradation process of the mulching film is further accelerated.

The degradable plastic is added with the bimetallic ligand catalyst, so that the degradable plastic provides possibility for realizing the degradation of the plastic in natural environments such as seawater and the like, the degradation of the plastic under the condition of composting and the accelerated degradation of a mulching film. Compared with a biological enzyme catalyst, the added bimetallic ligand catalyst is more stable; the catalyst has wider operable range compared with a biological enzyme catalyst when being mutually soluble with plastics; compared with a biological enzyme catalyst, the bimetallic ligand catalyst can be suitable for various polyesters and polyamide plastics, and breaks through the specificity limitation of the traditional biological enzyme catalyst.

Drawings

FIG. 1 is a graph of the mass loss of a PLA film over time in example 1.

Fig. 2 is a plot of mass loss over time for the catalyst-containing PBAT membrane of example 2.

FIG. 3 is a powder X-ray characterization of the complex of example 5.

FIG. 4 is a graph of the mass loss of the catalyst-containing PLA film over time in example 12.

FIG. 5 is a graph showing the conversion curve of the catalyst-containing PET film of example 13 in seawater.

FIG. 6 is a plot of mass loss over time for catalyst-containing PLA pellets in example 14.

Detailed Description

In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

All numerical designations herein (e.g., temperature, time, concentration, and weight, etc., including ranges for each) may generally be approximated as varied (+) or (-) in increments of 0.1 or 1.0, as appropriate. All numerical designations should be understood to be preceded by the term "about".

Conversion = amount of reacted plastic/total input of plastic, wherein the amount of reacted plastic is determined by conversion from amount of monomer obtained by reaction, and the amount of monomer obtained by reaction is quantified by nuclear magnetic hydrogen spectrum.

Example 1

The degradable plastic of the embodiment is PLA; the bimetallic complex used has the chemical formula Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ The structural formula is as follows:

1) Bimetallic complex Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ The preparation of (1):

the synthesis of the bimetallic complexes is described in Pilkington N H, robson R.complexes of binding ligands, III. Novel complexes of a macroporous binding ligand, aust.J.Chem.,1970,23,2225-2236, in which the zinc chloride and zinc acetate used are replaced by zinc nitrate hexahydrate in amounts corresponding to the molar sum of the two, and the remainder of the procedure is unchanged to give a yellow solid.

The nuclear magnetism of the bimetallic complex is characterized in that: ¹ H NMR(400MHz,D ₂ O):δ8.26(s,4H,N＝CH),7.34(s,4H,Ar),3.92(s,8H,N–CH ₂ ),2.20(s,6H,Ar–CH ₃ ),2.04(s,4H,CH ₂ )。

2) Preparation of PLA film containing bimetallic complex:

10mg of PLA and 1mg of Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ Dissolved in dichloromethane and then spin-evaporated to obtain a PLA film containing the catalyst.

In the same way, PLA films without catalyst were also prepared.

3) PLA film hydrolysis test:

PLA film hydrolysis test conditions: 10mg of PLA film prepared above was placed at 10mL 10 ^-6 Hydrolysis reaction is carried out in the M NaOH solution, the reaction temperature is 40 ℃, and the reaction time is 8 days. The test results are shown in table 1 and fig. 1.

TABLE 1

Hydrolyzing a substrate	Catalyst-containing PLA film	Catalyst-free PLA film
			Conversion rate/%	78	25

Note: the reaction conditions for the catalyst-free PLA film were the same as the catalyst-containing PLA film test conditions.

As can be seen from Table 1 and FIG. 1, [ Zn ] was used ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ ]The hydrolysis effect of the additive is obviously higher than that of the additive-free additive, which shows that [ Zn ] ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ ]Can be used as a plastic additive to effectively degrade PLA.

Example 2

The degradable plastic of this example is PBAT; the bimetallic complex used has the chemical formula [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The structural formula is as follows:

1) Bimetallic complexes [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The preparation of (1):

the synthesis of the bimetallic complex is similar to the method in example 1, and 2-hydroxy-5-methyl isophthalaldehyde is replaced by 2-hydroxy-5-ethyl isophthalaldehyde, and the bimetallic complex is stood to separate out light yellow solid, filtered and dried.

The nuclear magnetism of the bimetallic complex is characterized in that: nuclear magnetic characterization ¹ H NMR(400MHz,D ₂ O):δ8.53(s,4H,N＝CH),7.58(s,4H,Ar),3.98(s,8H,N–CH ₂ ),2.59(q,4H,Ar–CH ₂ ),2.03(s,4H,CH ₂ ),1.20(t,6H,–CH ₃ )。

2) Preparation of a PBAT membrane containing a bimetallic complex:

10mg of PBAT and 1mg of Zn ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Dissolved in dichloromethane and then spin evaporated to obtain catalyst-containing PBAT membranes.

In the same way, a PBAT membrane without catalyst was also prepared.

3) PBAT membrane hydrolysis test:

PBAT membrane hydrolysis test conditions: 10mg of the PBAT membrane prepared above was placed in 10mL 10 ^-6 Hydrolysis reaction is carried out in the M NaOH solution, the reaction temperature is 40 ℃, and the reaction time is 8 days. The test results are shown in table 2 and fig. 2.

TABLE 2

Hydrolysis of substrates	Catalyst-containing PBAT membranes	Catalyst-free PBAT membranes
			Conversion rate/%	45	12

Note: the reaction conditions for the catalyst-free PBAT membrane were the same as the catalyst-containing PBAT membrane test conditions.

As can be seen from Table 2 and FIG. 2, [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The hydrolysis effect is obviously higher than that without the additive when the additive is used as the plastic additive, which shows that [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Can be used as a plastic additive to effectively degrade PBAT.

Example 3

The degradable plastic of the embodiment is PCL; the bimetallic complex used has the chemical formula [ Zn ] ₂ (C ₂₄ H ₂₆ N ₄ O ₄ )(NO ₃ ) ₂ ]The structural formula is as follows:

1) Bimetallic complexes [ Zn ] ₂ (C ₂₄ H ₂₆ N ₄ O ₄ )(NO ₃ ) ₂ ]The preparation of (1):

the synthesis of the bimetallic complex precursor 2-hydroxy-5-methoxy-isophthalaldehyde is described in Lindoy, L.F., meehan, G.V., svenstrup, N.Mono-and transformation of 4-substitated phenols, a new application of the complex, 1998,7, 1029-1032. Then, 0.5mmol of 1, 3-propanediamine and 0.5mmol of zinc nitrate are mixed, dissolved in 10ml of methanol, an equivalent amount of a methanol solution of 2-hydroxy-5-methoxy-isophthalaldehyde is added dropwise to the mixed solution, stirred at normal temperature for 10min and then kept stand to precipitate a yellow solid, and the yellow solid is filtered and dried.

The nuclear magnetism of the bimetallic complex is characterized in that: ¹ H NMR(400MHz,DMSO-d6):δ8.55(s,4H,N＝CH),7.41(s,4H,Ar),3.98(s,8H,N–CH ₂ ),2.05(s,4H,CH ₂ )。

2) Preparing a PCL film containing a bimetallic complex:

10mg of PCL and 1mg of Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₄ )(NO ₃ ) ₂ ]Dissolved in toluene and then spin-evaporated to obtain PCL film containing catalyst.

In the same way, PCL films without catalyst were also prepared.

3) And (3) PCL membrane hydrolysis test:

testing conditions for hydrolysis of PCL membrane: 10mg of PCL film prepared above was placed in 10mL 10 ^-6 Hydrolysis reaction is carried out in the M NaOH solution, the reaction temperature is 40 ℃, and the reaction time is 8 days. The test results are shown in table 3.

TABLE 3

Hydrolysis of substrates	PCL film containing catalyst	Catalyst-free PCL films
			Conversion rate/%)	66	24

Note: the reaction conditions of the catalyst-free PCL film were the same as the test conditions of the catalyst-containing PCL film.

As can be seen from Table 3, [ Zn ] was used ₂ (C ₂₄ H ₂₆ N ₄ O ₄ )(NO ₃ ) ₂ ]The hydrolysis effect is obviously higher than that without the additive when the additive is used as the plastic additive, which shows that [ Zn ] ₂ (C ₂₄ H ₂₆ N ₄ O ₄ )(NO ₃ ) ₂ ]Can be used as a plastic additive to effectively degrade PCL.

Example 4

The degradable plastic in the embodiment is TPU; the bimetallic complex used has the chemical formula [ Zn ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]The structural formula is as follows:

1) Bimetallic complexes [ Zn ] ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]The preparation of (1):

bimetallic complexes [ Zn ] ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]Synthetic references of Pilkington N H, robson R. Compounds of binding ligands III. Novel compounds of a macromolecular bindingThe method given in ligand, aust.j.chem.,1970,23,2225-2236, wherein 2-hydroxy-5-methyl isophthalaldehyde used was replaced with an equal molar amount of 2-hydroxy-5-tert-butyl isophthalaldehyde, and zinc chloride and zinc acetate were replaced with zinc nitrate hexahydrate in an amount equal to the sum of the molar amounts thereof, and the rest of the procedure was unchanged to give a yellow solid.

The nuclear magnetism of the bimetallic complex is characterized in that: ¹ H NMR(400MHz,DMSO-d6):δ8.61(s,4H,N＝CH),7.76(s,4H,Ar),3.98(s,8H,N–CH ₂ ),2.03(s,4H,CH ₂ ),1.30(s,18H,Ar–C–CH ₃ )。

2) Preparation of a TPU film containing a bimetallic complex:

mixing 10mg of TPU and 1mg of Zn ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]Dissolved in chloroform and then the catalyst containing TPU film was obtained by rotary evaporation.

In the same way, TPU films without catalyst are also prepared.

3) Hydrolysis test of TPU film:

the hydrolysis test conditions of the TPU film are as follows: 10mg of the TPU film prepared above was placed in 10mL of 10 ^-6 Hydrolysis reaction is carried out in the M NaOH solution, the reaction temperature is 40 ℃, and the reaction time is 8 days. The test results are shown in table 4.

TABLE 4

Hydrolysis of substrates	TPU film containing catalyst	Catalyst-free TPU films
			Conversion rate/%	86	12

Note: the reaction conditions for the catalyst-free TPU membrane were the same as for the catalyst-containing TPU membrane test conditions.

As can be seen from Table 4, [ Zn ] was used ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]The hydrolysis effect is obviously higher than that without the additive when the additive is used as the plastic additive, which shows that [ Zn ] ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]Can be used as a plastic additive to effectively degrade TPU.

Example 5

The degradable plastic of this example is PC; the bimetallic complex used has the chemical formula [ Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(OH) ₂ ]The structural formula is as follows:

1) Bimetallic complex [ Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(OH) ₂ ]The preparation of (1):

synthesis of the Complex [ Zn ] according to example 1 ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ ]Then dissolving the mixture in 0.2M KOH solution, stirring for 24 hours, filtering and drying to obtain the catalyst. The X-ray diffraction characterization data of the obtained bimetallic complex powder are shown in FIG. 3.

2) Preparation of a PC film containing a bimetallic complex:

mixing 10mg of PC and 1mg of Zn [ alpha ] ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(OH) ₂ ]Dissolved in dichloromethane and then spin evaporated to obtain a catalyst containing PC film.

In the same way, a catalyst-free PC membrane was also prepared.

3) PC membrane hydrolysis test:

PC membrane hydrolysis test conditions: 10mg of the PC film prepared above was placed in 10mL of 10 ^-6 M NaOH solutionThe hydrolysis reaction is carried out at the reaction temperature of 60 ℃ for 12 days. The test results are shown in table 5.

TABLE 5

Hydrolysis of substrates	Catalyst-containing PC membrane	Catalyst-free PC membrane
			Conversion rate/%	56	20

Note: the reaction conditions for the catalyst-free PC membrane were the same as the catalyst-containing PC membrane test conditions.

As can be seen from Table 5, [ Zn ] was used ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(OH) ₂ ]The catalytic effect is obviously higher than that of the additive-free plastic additive, which shows that [ Zn ] ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(OH) ₂ ]Can be used as a plastic additive to effectively degrade PC.

Example 6

The degradable plastic of the embodiment is PLA; the chemical formula of the bimetallic complex is Cu ₂ (C ₁₇ H ₂₃ N ₄ O ₃ )(ClO ₄ ) ₂ The structural formula is as follows:

1) Bimetallic complex Cu ₂ (C ₁₇ H ₂₃ N ₄ O ₃ )(ClO ₄ ) ₂ The preparation of (1):

synthetic references Mazurek, w. for the bimetallic complexes; kennedy, b.j.; murray, k.s.; o' Connor, m.j.; rodgers, j.r.; snow, m.r.; wedd, a.g.; zwack, P.R. magnetic Interactions in Metal Complexes of binding ligands.2.Synthesis and Properties of binding coater (II) Compounds of binding Ligands of homology Ligands of Bridge through atom of Crystal and Molecular Structure of a binding mu-paramagnetic-N, N' -Bridge linker (II) Complex of l,3-Bis (salicylideneamino) expand-2-ol. Inorg. Chem.1985,24, 3258-3264.

2) Preparation of PLA film containing bimetallic complex:

10mg of PLA and 2mg of Cu ₂ (C ₁₇ H ₂₃ N ₄ O ₃ )(ClO ₄ ) ₂ Dissolved in dichloromethane and then spin evaporated to obtain catalyst-containing PLA films.

In the same way, PLA films without catalyst were also prepared.

3) PLA film hydrolysis test:

PLA film hydrolysis test conditions: place 10mg of PLA film prepared above 10mL ^-6 Hydrolysis reaction is carried out in M NaOH solution, the reaction temperature is 40 ℃, and the reaction time is 8 days. The test results are shown in table 6.

TABLE 6

Hydrolysis of substrates	Catalyst-containing PLA films	Catalyst-free PLA films
			Conversion rate/%	58	22

As shown in Table 6, cu was used ₂ (C ₁₇ H ₂₃ N ₄ O ₃ )(ClO ₄ ) ₂ When the additive is used as a plastic additive, the hydrolysis effect is obviously higher than that of the additive-free additive, shows Cu ₂ (C ₁₇ H ₂₃ N ₄ O ₃ )(ClO ₄ ) ₂ Can be used as a plastic additive to effectively degrade PLA.

Example 7

The degradable plastic of the embodiment is PCL; the chemical formula of the bimetallic complex is Zn ₂ (C ₂₂ H ₂₀ Br ₂ N ₄ O ₂ )(NO ₃ ) ₂ The structural formula is as follows:

1) Bimetallic complex Zn ₂ (C ₂₂ H ₂₀ Br ₂ N ₄ O ₂ )(NO ₃ ) ₂ The preparation of (1):

the precursor of the bimetallic complex, 5-bromo-2-hydroxyisophthalaldehyde, is synthesized by the method given in Leonard F.Lindoy, george V.Meehan, niels Svensstrup. Mono-and Diformylation of 4-substistuted Phenols: A New Application of the Duff Reaction, synthesis,1998,7, 1029-1032. With the complex [ Zn ] in example 3 ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]The synthesis method is similar, 2-hydroxy-5-methoxyl isophthalaldehyde is replaced by 5-bromo-2-hydroxyl isophthalaldehyde, and the mixture is kept stand to separate out light yellow solid, filtered and dried to obtain the product.

The nuclear magnetism of the bimetallic complex is characterized in that: ¹ H NMR(400MHz,DMSO-d6):δ8.53(s,4H,N＝CH),7.94(s,4H,Ar),3.96(s,8H,N–CH ₂ ),2.06(s,4H,CH ₂ )。

2) Preparing a PCL film containing a bimetallic complex:

10mg of PLA and 0.5mg of Zn ₂ (C ₂₂ H ₂₀ Br ₂ N ₄ O ₂ )(NO ₃ ) ₂ Dissolved in toluene and then spin evaporated to obtain PCL film containing catalyst.

In the same way, PCL films without catalyst were also prepared.

3) And (3) PCL membrane hydrolysis test:

testing conditions for hydrolysis of PCL membrane: 10mg of PC film L prepared above was placed in 10mL of 10 ^-6 Hydrolysis reaction is carried out in the M NaOH solution, the reaction temperature is 40 ℃, and the reaction time is 8 days. The test results are shown in table 7.

TABLE 7

Hydrolyzing a substrate	PCL film containing catalyst	Catalyst-free PCL films
			Conversion rate/%	52	18

Note: the reaction conditions of the catalyst-free PCL film are the same as the testing conditions of the catalyst-containing PCL film.

As can be seen from Table 7, zn is used ₂ (C ₂₂ H ₂₀ Br ₂ N ₄ O ₂ )(NO ₃ ) ₂ The hydrolysis effect is obviously higher than that of the additive-free additive when the additive is used as a plastic additive, which indicates that Zn ₂ (C ₂₂ H ₂₀ Br ₂ N ₄ O ₂ )(NO ₃ ) ₂ Can be used as a plastic additive to effectively degrade PCL.

Example 8

The degradable plastic of this example is PEF; the chemical formula of the bimetallic complex is Zn ₂ (C ₂₂ H ₂₂ N ₄ O ₂ )(NO ₃ ) ₂ The structural formula is as follows:

1) Bimetallic complex Zn ₂ (C ₂₂ H ₂₂ N ₄ O ₂ )(NO ₃ ) ₂ The preparation of (1):

the synthesis of the bimetallic complex is disclosed in Pilkington N H, robson R.complex of binding ligands, III. Novel complexes of a macromolecular binding ligand, aust.J.Chem.1970, 23,2225-2236, wherein 2-hydroxy-5-methyl-m-xylene formaldehyde is replaced by 2-hydroxy-m-xylene formaldehyde, and the bimetallic complex is allowed to stand to separate out a yellowish solid, filtered and dried.

The nuclear magnetism of the bimetallic complex is characterized as follows: ¹ H NMR(400MHz,DMSO-d6):δ8.56(s,4H,N＝CH),7.72(d,4H,Ar),7.03(t,2H,Ar),3.99(s,8H,N–CH ₂ ),2.05(s,4H,CH ₂ )。

2) Preparation of a PEF film containing a bimetallic complex:

10mg of PEF and 0.5mg of Zn ₂ (C ₂₂ H ₂₂ N ₄ O ₂ )(NO ₃ ) ₂ Dissolved in toluene and then spin evaporated to obtain catalyst containing PEF film.

In the same way, catalyst-free PEF membranes were also prepared.

3) PEF membrane hydrolysis test:

PEF membrane hydrolysis test conditions: 10mg of the PCL film prepared above was placed in 10mL of 10 ^-6 Hydrolysis reaction is carried out in M NaOH solution, the reaction temperature is 40 ℃, and the reaction time is 8 days. The test results are shown in table 8.

TABLE 8

Hydrolyzing a substrate	Catalyst-containing PEF membrane	Catalyst-free PEF membranes
			Conversion rate/%	64	25

Note: the reaction conditions for the catalyst-free PEF membrane were the same as the test conditions for the catalyst-containing PEF membrane.

As can be seen from Table 8, zn is used ₂ (C ₂₂ H ₂₂ N ₄ O ₂ )(NO ₃ ) ₂ The catalytic effect is obviously higher than that of the additive-free catalyst when the additive is used as a plastic additive, which shows that Zn ₂ (C ₂₂ H ₂₂ N ₄ O ₂ )(NO ₃ ) ₂ Can be used as a plastic additive to effectively degrade PEF.

Example 9

The degradable plastic of the embodiment is PET; the bimetallic complex used is that of example 2, of the formula: [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]。

1) Preparation of the PET film containing the bimetallic complex:

mixing 10mg of PET and 1mg of [ Zn ], [ solution ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Dissolved in hexafluoroisopropanol and then evaporated to dryness by spin coating to obtain a catalyst-containing PET film.

In the same way, a catalyst-free PET film was also prepared.

2) Hydrolysis test of PET film:

hydrolysis test conditions of the PET film: 10mg of the PET film prepared above was placed in 10mL of 0.1M NaOH solution to perform hydrolysis reaction at 60 ℃ for 2 days. The test results are shown in table 9.

TABLE 9

Hydrolysis of substrates	Catalyst-containing PET film	Catalyst-free PET film
			Conversion rate/%	95	6

Note: the reaction conditions for the catalyst-free PET film were the same as the test conditions for the catalyst-containing PET film.

As can be seen from Table 9, [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The hydrolysis effect is obviously higher than that of the additive-free plastic additive, which shows that [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Can be used as a plastic additive to effectively degrade PET.

Example 10

The degradable plastic of the embodiment is PGA; the bimetallic complex used is that of example 2, of the formula: [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]。

1) Preparation of PGA film containing bimetallic complex:

mixing 10mg of PGA and 1mg of [ Zn ], [ solution ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Dissolved in chloroform and then evaporated by spin coating to obtain a catalyst-containing PGA film.

In the same way, PGA films containing no catalyst were also prepared.

2) PGA film hydrolysis test:

PGA film hydrolysis test conditions: 10mg of the PGA film prepared above was placed in 10mL of 0.01M NaOH solution at 60 ℃ for 2 days to effect hydrolysis reaction. The test results are shown in table 10.

Watch 10

Hydrolysis of substrates	Catalyst-containing PGA membrane	Catalyst-free PGA film
			Conversion rate/%	92	36

Note: the reaction conditions of the catalyst-free PGA film were the same as those of the catalyst-containing PGA film test conditions.

As can be seen from Table 10, [ Zn ] was used ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The hydrolysis effect is obviously higher than that of the additive-free plastic additive, which shows that [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Can be used as plastic additive to effectively degrade PGA.

Example 11

The degradable plastic of this example is PBA; the bimetallic complex used is the bimetallic complex of example 3, of the formula [ Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₄ )(NO ₃ ) ₂ ]。

1) Preparation of PBA membrane containing bimetallic complex:

mixing 10mg of PBA and 0.5mg of Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₄ )(NO ₃ ) ₂ ]Dissolved in hexafluoroisopropanol and then evaporated to dryness by spin coating to obtain catalyst-containing PBA films.

In the same way, catalyst-free PBA membranes were also prepared.

2) PBA membrane hydrolysis test:

PBA membrane hydrolysis test conditions: 10mg of the PBA membrane prepared above was placed in 10mL of 0.1M NaOH solution to perform hydrolysis reaction at 60 ℃ for 3 days. The test results are shown in table 11.

TABLE 11

Hydrolysis of substrates	PBA membranes containing catalyst	Catalyst-free PBA membranes
			Conversion rate/%	86	11

Note: the reaction conditions for the catalyst-free PBA membrane were the same as the catalyst-containing PBA membrane test conditions.

As can be seen from Table 11, [ Zn ] was used ₂ (C ₂₄ H ₂₆ N ₄ O ₄ )(NO ₃ ) ₂ ]The hydrolysis effect is obviously higher than that without the additive when the additive is used as the plastic additive, which shows that [ Zn ] ₂ (C ₂₄ H ₂₆ N ₄ O ₄ )(NO ₃ ) ₂ ]Can be used as a plastic additive to effectively degrade PBA.

Example 12

The degradable plastic of the embodiment is PLA; the complex used is the catalyst of example 4 of the formula [ Zn ] ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]。

1) Preparation of PLA film containing metal complex:

10mg of PLA and 2mg of [ 2 ] Zn ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]Dissolved in chloroform and then spin-evaporated to obtain a PLA film containing the catalyst.

In the same way, PLA films without catalyst were also prepared.

2) PLA film hydrolysis test:

PLA film hydrolysis test conditions: 10mg of PLA film prepared above was placed at 10mL 10 ^-6 Carrying out hydrolysis reaction in the M seawater solution at the reaction temperature of 60 ℃ for 6.7 days. The test results are shown in table 12 and fig. 4.

TABLE 12

Hydrolysis of substrates	Catalyst-containing PLA films	Catalyst-free PLA films
			Conversion rate/%	93	26

As is clear from Table 12 and FIG. 4, [ Zn ] was used ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]The catalytic effect is obviously higher than that without the additive when the additive is used as the plastic additive, which shows that [ Zn ] ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]Can be used as a plastic additive to effectively degrade PLA.

Example 13

1) Preparation of the PET film containing the bimetallic complex:

mixing 10mg of PET and 0.5mg of Zn ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Dissolved in hexafluoroisopropanol and then evaporated to dryness by spin coating to obtain a catalyst-containing PET film.

In the same way, a catalyst-free PET film was also prepared.

2) Hydrolysis test of PET film:

hydrolysis test conditions of the PET film: 10mg of the above-prepared PET film was placed in 10mL of seawater (pH = 7.9) to perform a hydrolysis reaction at a reaction temperature of 90 ℃ for 14 days. The test results are shown in table 13 and fig. 5.

Watch 13

Hydrolysis of substrates	Catalyst-containing PET film	Catalyst-free PET film
			Conversion rate/%	15	0

As can be seen from Table 13 and FIG. 5, [ Zn ] was used under real seawater environment conditions ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The hydrolysis effect is obviously higher than that without the additive when the additive is used as the plastic additive, which shows that [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The PET plastic additive provides possibility for realizing plastic degradation under seawater environmental conditions.

Example 14

The degradable plastic of the embodiment is PLA; the bimetallic complex used is that of example 1, of the formula: zn ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ 。

1) Preparation of PLA beads containing bimetallic complexes:

6g of PLA and 0.1g of Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ Dissolving in dichloromethane, and then pouring into a spherical mold for evaporation to obtain PLA spheres containing the catalyst.

In the same way, PLA pellets without catalyst were also prepared.

2) And (3) performing hydrolysis test on PLA balls:

PLA ball hydrolysis test conditions: 6g of the above-prepared PLA pellets were put in 3 cubic meters of compost (pH = 8) to undergo hydrolysis reaction at a reaction temperature of 60 ℃ for 28 days. The test results are shown in table 14 and fig. 6.

TABLE 14

Hydrolysis of substrates	Catalyst-containing PLA (polylactic acid) ball	Catalyst-free PLA spheres
			Conversion rate/%	87	12

Note: the reaction conditions for the catalyst-free PLA pellets were the same as the catalyst-containing PLA pellet test conditions.

As can be seen from Table 14 and FIG. 6, zn was used under composting conditions ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ The catalytic effect is obviously higher than the hydrolysis effect without the additive when the additive is used as a plastic additive, and the indication shows that Zn ₂ (C ₂₄ H ₂₆ N ₄ O ₂ )(NO ₃ ) ₂ The PLA plastic additive provides possibility for realizing plastic degradation under the composting environmental condition.

Example 15

The degradable plastic of the embodiment is nylon 66; the bimetallic complex used is that of example 2, of the formula: [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]。

1) Preparation of nylon 66 membrane containing bimetallic complex:

mixing 10mg of nylon and 0.5mg of Zn ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Dissolved in m-cresol and then evaporated to dryness by spin coating to obtain a catalyst-containing nylon 66 film.

In the same way, a catalyst-free nylon 66 membrane was also prepared.

2) Nylon 66 membrane hydrolysis test:

nylon 66 membrane hydrolysis test conditions: 10mg of the nylon 66 membrane prepared above was placed in 10mL of 0.1M NaOH aqueous solution to perform hydrolysis reaction at 60 ℃ for 2 days. The test results are shown in table 15.

Watch 15

Hydrolyzing a substrate	Catalyst-containing nylon 66 membrane	Catalyst-free nylon 66 membrane
			Conversion rate/%	20	0

Note: the reaction conditions for the catalyst-free nylon 66 membrane were the same as the catalyst-containing nylon 66 membrane test conditions.

As can be seen from Table 15, [ Zn ] was used ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The hydrolysis effect is obviously higher than that of the additive-free plastic additive, which shows that [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Can be used as a plastic additive to effectively degrade nylon 66.

Example 16

1) Preparing a PET film containing a bimetallic complex:

mixing 10mg of PET and 0.5mg of Zn ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]Melted at 250 ℃ and then extruded by molding to obtain a catalyst-containing PET film.

In the same way, a catalyst-free PET film was also prepared.

2) Hydrolysis test of PET film:

hydrolysis test conditions of the PET film: 10mg of the PET film prepared above was put in 3 cubic meters of compost (pH = 8) to perform hydrolysis reaction at 60 ℃ for 30 days. The test results are shown in Table 16.

TABLE 16

Hydrolysis of substrates	Catalyst-containing PET film	Catalyst-free PET film
			Conversion rate/%	35	0

As can be seen from Table 16, [ Zn ] was used under composting conditions ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The degradation effect is obviously higher than that without the additive when the additive is used as the plastic additive, which shows that [ Zn ] ₂ (C ₂₆ H ₃₀ N ₄ O ₂ )(NO ₃ ) ₂ ]The PET plastic additive provides possibility for realizing plastic degradation under the composting environmental condition. In addition, the method also provides possibility for accelerating the degradation of the mulching film in the farmland.

Example 17

The degradable plastic of the embodiment is PLA; the complex used is the catalyst of example 4, of the formula [ Zn ] ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]。

1) Preparation of PLA films containing metal complexes:

50mg of 1500 mesh PLA was dispersed in a dispersion containing 2.5mg of [ Zn ]) ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]The catalyst-containing PLA membrane is obtained by fully adsorbing, filtering, drying and then extruding to form the membrane.

In the same way, PLA films without catalyst were also prepared.

2) PLA film hydrolysis test:

PLA film hydrolysis test conditions: place 10mg of PLA film prepared above 10mL ^-6 Carrying out hydrolysis reaction in the M seawater solution at the reaction temperature of 60 ℃ for 8 days. The test results are shown in table 17.

TABLE 17

Hydrolyzing a substrate	Catalyst-containing PLA film	Catalyst-free PLA films
			Conversion rate/%)	80	20

As can be seen from Table 17, [ Zn ] was used in a real seawater environment ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]The catalytic effect is obviously higher than that of the additive-free plastic additive, which shows that [ Zn ] ₂ (C ₃₀ H ₃₈ N ₄ O ₂ )(NO ₃ ) ₂ ]Can be used as a plastic additive to effectively realize the degradation of PLA in the natural environment.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.

Claims

1. A degradable plastic is characterized by comprising a catalyst for catalyzing the degradation of the plastic, wherein the catalyst is a bimetallic complex; the degradable plastic is polyester or polyamide plastic;

the bimetallic complex is selected from compounds with the structural general formula of the following formula 1 or formula 4:

wherein, M ₁ And M ₂ Represents a metal atom independently selected from Fe, co, ni, cu, zn, mg, ca, mn, ru, pd or Pt, and M ₁ And M ₂ Between two atoms of

X is ClO ₄ ^– ；

In formula 4, Y is selected from NO ₃ ^– 、Cl ^– 、Br ^– 、OAc ^– 、ClO ₄ ^– 、OH ^– Or SO ₄ ^2– (ii) a When Y is selected from NO ₃ ^– 、Cl ^– 、Br ^– 、OAc ^– 、ClO ₄ ^– Or OH ^– When m = p; when Y is SO ₄ ^2– When m =0.5p;

R ₃ independently selected from H, hydrocarbyl, halogen, hydroxy or carboxy;

R ₁ 、R ₁ ' is-CH ₂ -CH ₂ -CH ₂ -；

2. The degradable plastic of claim 1, wherein the hydrocarbyl group comprises a C1-C6 alkyl group.

3. The degradable plastic of claim 2, wherein the bimetallic complex has the structure:

4. the degradable plastic of claim 1, wherein the polyester or polyamide plastic is selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, polylactic acid, polycaprolactone, polybutylene adipate/terephthalate, polycarbonate, polyethylene-2, 5-furandicarboxylate, polybutylene succinate, polybutylene adipate, poly-3-hydroxybutyrate and poly (3-hydroxybutyrate-4-hydroxybutyrate), nylon 66, and combinations of two or more thereof.

5. The degradable plastic of claim 4, wherein the bimetallic complex is 0.05wt.% to 20wt.% of the polyester or polyamide plastic.

6. A method for preparing the degradable plastic of any one of claims 1 to 5, wherein the method comprises the following steps:

dissolving polyester or polyamide plastic and a bimetallic complex in an organic solvent, and then removing the solvent to obtain degradable plastic containing the bimetallic complex; or alternatively

Melting polyester or polyamide plastics and a bimetallic complex at high temperature, and then molding and extruding to obtain degradable plastics containing the bimetallic complex; or alternatively

Mixing polyester or polyamide plastic and a bimetallic complex and fully ball-milling to obtain degradable plastic containing the bimetallic complex; or alternatively

The polyester or polyamide plastics are smashed into fine particles, then the fine particles are soaked in an aqueous solution containing the bimetallic complex, the plastic particles fully adsorb the bimetallic complex, and finally a solid mixture is separated out and is extruded and molded to obtain the degradable plastic containing the bimetallic complex.

7. The method according to claim 6, wherein the organic solvent is one or a combination of two or more selected from the group consisting of methylene chloride, toluene, chloroform, hexafluoroisopropanol, m-cresol, tetrahydrofuran, and N, N-dimethylformamide.

8. The method of claim 6, wherein the temperature of the high temperature melting and shaping extrusion is 180-300 ℃.

9. The method according to claim 6, wherein the polyester or polyamide plastic is broken into fine particles with a mesh size of 800-1500 mesh.