阅读说明：本技术 一种络合显色聚酰胺的制备方法 (Preparation method of complex color-developing polyamide ) 是由 赵京波 张云帆 张军营 于 2020-06-22 设计创作，主要内容包括：一种络合显色聚酰胺的制备方法,属于聚酰胺领域。首先利用哌嗪与丙烯酸酯进行本体迈克尔加成,合成哌嗪二酯单体；将其与不同的二胺本体缩聚,获得主链中含有哌嗪环的线型聚酰胺；以氯化钴溶液对其络合改性,其玻璃化转变温度、力学强度和杨氏模量得到大幅提升；络合后的聚酰胺对水及甲醇有良好的溶剂变色性能。该制备方法操作简便,生产成本低,便于商业化生产,有望在材料增强、溶剂指示剂、防伪材料等领域,拥有广阔的应用前景。(A preparation method of complex chromogenic polyamide, belonging to the field of polyamide. Firstly, carrying out bulk Michael addition on piperazine and acrylate to synthesize a piperazine diester monomer; the polyamide is subjected to polycondensation with different diamines to obtain linear polyamide with a main chain containing piperazine rings; the cobalt chloride solution is used for complexing modification, so that the glass transition temperature, the mechanical strength and the Young modulus of the cobalt chloride solution are greatly improved; the complexed polyamide has good solvent discoloration performance on water and methanol. The preparation method is simple and convenient to operate, low in production cost and convenient for commercial production, is expected to be applied to the fields of material reinforcement, solvent indicators, anti-counterfeiting materials and the like, and has wide application prospects.)

1. A preparation method of complex color-developing polyamide is characterized in that anhydrous piperazine and acrylate are subjected to Michael addition reaction under the conditions of no catalyst and no solvent to synthesize a piperazine diester monomer; carrying out melt polycondensation on the piperazine derivative and different diamines to prepare linear polyamide with a main chain containing piperazine rings; complexing and modifying the polyamide with cobalt chloride solution to obtain complex color-developing polyamide; the method specifically comprises the following steps:

1) preparation of piperazine diester: feeding anhydrous piperazine and acrylate according to a molar ratio of 1 (2-2.5), carrying out bulk Michael addition reaction for 4-5 h at 50-70 ℃, removing excessive acrylate by rotary evaporation, and recrystallizing solid substances by petroleum ether to obtain white piperazine diester crystals;

2) preparation of linear polyamide with main chain containing piperazine ring: feeding piperazine diester prepared in the step 1) and diamine according to a molar ratio of 1 (1-1.05), performing melt polycondensation at 180-210 ℃ under the protection of nitrogen, performing pressure reduction reaction for 0.5-1 h by a water pump, and finally performing pressure reduction reaction for 2-6 h by an oil pump to 1-5 mmHg to obtain linear polyamide containing piperazine ring in the main chain;

3) preparation of complex color polyamide: hot-pressing the piperazine ring-containing linear polyamide prepared in the step 2) to form a dumbbell-shaped sample strip, and immersing the dumbbell-shaped sample strip into a cobalt chloride solution for sufficient swelling and complexing. Carefully taking out the sample strip after complexing, washing away the residual cobalt chloride on the surface by deionized water, placing the sample strip on a polytetrafluoroethylene film, drying the sample strip in a 50-60 ℃ drying oven until the size of the sample strip is basically stable, and then heating to 110-130 ℃ for drying for 6h to remove complexing water to obtain the cobalt ion complexing linear polyamide.

2. The method according to claim 1, wherein the piperazine diester monomer synthesized in step 1) has the structure shown in (i):

in the above formula R¹Is an alkyl group, and is,methyl and ethyl are preferred.

3. The process according to claim 1, wherein the diamine used in step 2) has the structure shown in (II):

H₂N-R²-NH₂

(II)

in the above formula R²Is- (CH)₂)_n(n is 2 to 10) or an aliphatic chain having an ether bond structure.

4. The method according to claim 3, wherein the diamine used in step 2) is one or more of 1, 6-hexanediamine, 1, 8-octanediamine and diethylene glycol bis (3-aminopropyl) ether.

5. The method according to claim 1, wherein the cobalt chloride solution used in step 3) is an aqueous solution or a methanol solution, and has a mass concentration of 1% to 5%.

6. A complex-colored polyamide prepared by the process according to any one of claims 1 to 5.

7. Use of a complex chromogenic polyamide prepared according to the process of any one of claims 1 to 5 for a discoloration response to water and methanol solvents.

Technical Field

The invention relates to a preparation method of complex color-developing polyamide. In particular to a method for synthesizing piperazine diester monomer by reacting anhydrous piperazine with acrylate, and then carrying out melt polycondensation with diamine to obtain linear polyamide with piperazine ring in the main chain; finally, the cobalt ions are used for carrying out complex modification on the composite material, so that the mechanical property of the material is improved, and the material is endowed with good solvent color-changing capability. Belongs to the technical field of polyamide.

Technical Field

Piperazine is used in small amounts in the biopharmaceutical field as a by-product in the production of ethylenediamine, and is also used in small amounts in the synthesis of polymers. Piperazine has been investigated for the preparation of polyamides. Heinrich et al (WO 2011062850A 2) synthesized a moisture-curing adhesive by direct polycondensation of piperazine with a dibasic acid or the like; nakagawa et al (JP 2010143888A and JP 2010070474A) use a crosslinked polyamide separation membrane containing a piperazine structure to separate and purify bio-based chemical raw materials such as butanol and succinic acid. In the piperazine-based polyamide, an amide bond is formed between a piperazine ring and a diacyl structure, and a nitrogen atom of the amide bond has no complexing ability and cannot be used for complexing color development.

The invention synthesizes piperazine diester through Michael addition reaction of piperazine and acrylic ester, and obtains linear polyamide containing piperazine ring in main chain through polycondensation with diamine. The polyamide has good crystallization performance and complexing ability, the mechanical property of the material is obviously improved after the complexing modification is carried out on the polyamide by cobalt ions, and the polyamide has good solvent discoloration performance. The complex chromogenic polyamide has the advantages of simple synthesis method, mild reaction conditions, high efficiency, low cost and convenient popularization and application.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a method for preparing complex color-developing polyamide with higher crystallinity and good mechanical property by using anhydrous piperazine as a raw material. Through the complexing modification of cobalt ions, the mechanical property of the polyamide can be further improved, and the polyamide has excellent solvent discoloration performance.

Firstly, taking anhydrous piperazine and acrylate as raw materials, and carrying out Michael addition reaction under the conditions of no catalyst and no solvent to synthesize a piperazine diester monomer; then the linear polyamide is polymerized with diamine in a bulk to prepare linear polyamide with a main chain containing piperazine ring; and complexing and modifying the polyamide by using a cobalt chloride solution to obtain the complex color-developing polyamide. The method comprises the following specific steps:

1) preparation of piperazine diester monomer: feeding anhydrous piperazine and acrylate according to a molar ratio of 1 (2-2.5), carrying out Michael addition reaction for 4-5 h at 50-70 ℃, removing excessive acrylate by rotary evaporation, and recrystallizing the obtained solid with petroleum ether to obtain a white piperazine diester crystal;

2) preparation of linear polyamide with main chain containing piperazine ring: feeding piperazine diester prepared in the step 1) and diamine according to a molar ratio of 1 (1-1.05), performing melt polycondensation at 180-210 ℃ under the protection of nitrogen, performing pressure reduction reaction for 0.5-1 h by a water pump, and finally performing pressure reduction reaction for 2-6 h to 1-5 mmHg by an oil pump to obtain linear polyamide with a main chain containing piperazine rings;

3) the preparation method of the complex color-developing polyamide comprises the following steps: hot-pressing the linear polyamide containing piperazine ring prepared in step 2) to form a sample strip, immersing the sample strip into a cobalt chloride solution, and performing sufficient swelling complexation; carefully taking out the sample strip after complexing, washing away the residual cobalt chloride on the surface by deionized water, placing the sample strip on a polytetrafluoroethylene film, drying the sample strip in a 50-60 ℃ oven until the size of the sample strip is basically stable, and heating to 110-130 ℃ for drying for 6h to remove a solvent such as complexing water to obtain cobalt ion complexing linear polyamide; the complex polyamide has good solvent color change response to water and methanol.

Wherein, the structure of the piperazine diester monomer synthesized in the step 1) is shown as the formula (I):

in the above formula R¹Is alkyl, preferably methyl, ethyl;

wherein the diamine used in step 2) has a structure represented by the general formula (II):

H₂NR²NH₂

(II)

in the above formula R²Is- (CH)₂)_nAn aliphatic chain such as (n-2 to 10) or an aliphatic chain containing an ether bond.

Wherein the cobalt chloride solution used in the step 3) is an aqueous solution or a methanol solution, and the mass concentration is 1-5%.

Wherein, the preparation mechanism of the cobalt ion complex in the step 3) is shown as a formula (III).

The invention has the following effects:

the method comprises the steps of firstly, synthesizing a piperazine diester monomer by using anhydrous piperazine and acrylate as raw materials through Michael addition reaction without adding a solvent or a catalyst; the aromatic polyamide is subjected to melt polycondensation with different diamines to obtain linear polyamide with a main chain containing piperazine rings. The specific structure is shown as a general formula (IV):

wherein R is²Is- (CH)₂)_n(n is 2 to 10) or an aliphatic chain having an ether bond structure.

The polyamide has excellent mechanical property, and series polymers with tensile strength of 7-31MPa and elongation at break of 58-720 percent can be prepared by using different diamines. The cobalt ions are used for carrying out complexing modification on the material, the glass transition temperature and the mechanical strength of the material are obviously improved, and the material has good solvent color-changing performance. The synthesis and modification method of the polymer is simple and convenient to operate, has low cost, is expected to be applied to the fields of solvent indicators, anti-counterfeiting materials and the like, and has wide application prospects.

Detailed Description

The intrinsic viscosity of the polymer in the present invention was measured by a one-point method using m-cresol as a solvent using an Ubbelohde viscometer. The glass transition temperature of the polymer was measured in accordance with GB/T19466.2-2004, using an apparatus DSC Q20 from TA.

According to the GB/T1040-2006 standard, the product is made into a standard dumbbell type sample, the stretching speed is 5mm/min, and the tensile strength and the elongation at break are measured by an INSTRON-1185 universal tensile machine.

The present invention will be described in detail below with reference to preferred examples according to the above-described embodiments, but the present invention is not limited to the following examples.