阅读说明：本技术 一种表面改性的阴离子聚合催化剂的制备方法 (Preparation method of surface-modified anionic polymerization catalyst ) 是由 甄彬 苏敏超 杨凤智 于 2021-08-03 设计创作，主要内容包括：本发明公开了一种表面改性的阴离子聚合催化剂的制备方法,其中,包括以下步骤:将离子型表面活性剂与芳烃混和后加热,获得无色透明溶液,再加入阴离子聚合催化剂,搅拌反应后得到表面活性剂包覆的阴离子聚合催化剂；将所述表面活性剂包覆的阴离子聚合催化剂过滤后获得白色固体,将所述白色固体用所述芳烃洗涤,洗涤好后的白色固体进行真空干燥,获得干燥好的白色固体,即表面改性的阴离子聚合催化剂。(The invention discloses a preparation method of a surface modified anionic polymerization catalyst, which comprises the following steps of mixing an ionic surfactant and aromatic hydrocarbon, heating to obtain a colorless transparent solution, adding the anionic polymerization catalyst, and stirring for reaction to obtain the anionic polymerization catalyst coated by the surfactant; filtering the anionic polymerization catalyst coated with the surfactant to obtain a white solid, washing the white solid with the aromatic hydrocarbon, and drying the washed white solid in vacuum to obtain a dried white solid, namely the surface-modified anionic polymerization catalyst.)

1. A method for preparing a surface-modified anionic polymerization catalyst, comprising the steps of:

mixing an ionic surfactant and aromatic hydrocarbon, heating to obtain a colorless transparent solution, adding an anionic polymerization catalyst, and stirring for reaction to obtain an anionic polymerization catalyst coated by the surfactant; wherein the mass ratio of the ionic surfactant to the aromatic hydrocarbon to the anionic polymerization catalyst is (5-30): 100: (1-20),

filtering the anionic polymerization catalyst coated with the surfactant to obtain a white solid, washing the white solid with the aromatic hydrocarbon, and drying the washed white solid in vacuum to obtain a dried white solid, namely the surface-modified anionic polymerization catalyst.

2. The method of claim 1, wherein the ionic surfactant comprises one or more of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, and cetyltrimethylammonium bromide.

3. The method of claim 1, wherein the aromatic hydrocarbon reacted with the ionic surfactant and the aromatic hydrocarbon washed with the white solid are the same, and the aromatic hydrocarbon comprises one or more of toluene, ethylbenzene, benzene, and xylene.

4. The method of claim 1, wherein the ionic surfactant is mixed with aromatic hydrocarbon and then placed in heat conducting oil to be heated, the heating temperature is 50-150 ℃, and the stirring is carried out for 30-480 min at the same time until the ionic surfactant is completely dissolved in the aromatic hydrocarbon, so as to obtain a colorless transparent solution.

5. The process of claim 1 wherein the anionic polymerization catalyst is a catalyst employed in perfluoropolyether synthesis comprising one or more of potassium fluoride or cesium fluoride.

6. The method according to claim 1, wherein the anionic polymerization catalyst is added to the colorless transparent solution under the condition of keeping the temperature unchanged, and after stirring for 30min to 480min, the surfactant-coated anionic polymerization catalyst is obtained.

7. The method of claim 1, wherein the washed white solid is placed in a vacuum drying oven at 50-150 ℃ and vacuum dried for 120-480 min to obtain a dried white solid, i.e. the surface modified anionic polymerization catalyst.

8. The method of claim 1, further comprising subjecting the surface-modified anionic polymerization catalyst to a moisture pick-up resistance measurement comprising exposing the surface-modified anionic polymerization catalyst to an indoor environment at a humidity of 50 to 80% and accurately weighing its mass at intervals for 24 to 72 hours, and recording the mass for each weighing.

9. A process for producing a perfluoropolyether, which employs the surface-modified anionic polymerization catalyst as claimed in any one of claims 1 to 8 as an anionic polymerization catalyst.

Technical Field

The invention belongs to the field of design, preparation and application of anionic polymerization catalysts, and particularly relates to a surface modification method of an anionic polymerization catalyst.

Background

The anti-fingerprint agent is an important auxiliary agent applied to the intelligent touch screen, and not only can the touch screen keep good appearance and comfortable hand feeling, but also the touch panel can be endowed with good waterproof and oil stain resistant performance. At present, the fingerprint resisting agent used in the market is mainly a perfluoropolyether modified silane coupling agent. Fluorine atoms in perfluoropolyether molecules replace all hydrogen atoms, and because the fluorine atoms have extremely strong electronegativity and small intermolecular attraction, the surface tension is small, and the perfluoropolyether lubricating grease has good lubricating property and oil stain resistance.

The main synthesis process routes of perfluoropolyether are divided into two, namely a photooxidation method and an anion polymerization method. The photooxidation method refers to a polyether compound obtained by irradiating tetrafluoroethylene or hexafluoropropylene with oxygen at a low temperature. The anionic polymerization method is to prepare perfluoroepoxide oligomer by taking perfluoroepoxide as a raw material and potassium fluoride or cesium fluoride as a catalyst in an aprotic solvent through polymerization at low temperature. Compared with the photooxidation method, the anion polymerization method has relatively low requirements on test equipment, operating environment and the like, and is concerned by more enterprises and researchers.

The solvent employed for anionic polymerization is generally an aprotic solvent, such as diethylene glycol dimethyl ether. The water content in the solvent has a great influence on the anionic polymerization reaction, and when the water content in the solvent is high, the anionic polymerization reaction tends to be impossible, or the molecular weight of the polymerization product is low. Therefore, it is often necessary to dry and re-evaporate the solvent before carrying out the anionic polymerization.

The catalysts used in anionic polymerization are generally potassium fluoride or cesium fluoride, both of which are highly hygroscopic and cause failure of the anionic polymerization reaction. Therefore, when conducting anionic polymerization tests, an anhydrous and oxygen-free environment is often required and the operating process is very demanding. Such as when the catalyst or charge is weighed, exposure to atmospheric moisture can have a significant adverse effect on the anionic polymerization reaction. This presents a serious inconvenience to the storage, transport and use of both potassium fluoride and cesium fluoride catalysts.

The moisture absorption has negative influence on the performance and application of many inorganic salt materials, so that many documents report moisture absorption mechanisms and prevention and control means of different inorganic salt materials. Liubo et al reported the development of ammonium dinitramide moisture absorption prevention technology (chemical propellant and polymer material, 2011,9(6): 57-60.). Wuxiang et al use KH560 to modify the surface of calcined dolomite to improve its moisture absorption resistance (non-ferrous metals (smelted parts), 2016,12: 23-26.). The surfactin is used to surface-modify potassium nitrate to prevent potassium nitrate from absorbing moisture and caking (inorganic salts industry, 1992,6: 25-27.). And sodium fluosilicate is modified by adopting sulfate and sulfonate surfactants, so that the problems of moisture absorption and caking of the sodium fluosilicate are solved.

Disclosure of Invention

In order to solve the above technical problems, the present invention aims to provide a method for preparing a surface-modified anionic polymerization catalyst having good moisture absorption resistance.

In order to achieve the above objects, the present invention provides a method for preparing a surface-modified anionic polymerization catalyst, comprising the steps of:

mixing an ionic surfactant and aromatic hydrocarbon, heating to obtain a colorless transparent solution, adding an anionic polymerization catalyst, and stirring for reaction to obtain an anionic polymerization catalyst coated by the surfactant; wherein the mass ratio of the ionic surfactant to the aromatic hydrocarbon to the anionic polymerization catalyst is (5-30): 100: (1-20),

filtering the anionic polymerization catalyst coated with the surfactant to obtain a white solid, washing the white solid with the aromatic hydrocarbon, and drying the washed white solid in vacuum to obtain a dried white solid, namely the surface-modified anionic polymerization catalyst.

In one embodiment of the present invention, the ionic surfactant includes, but is not limited to, one or more of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, and cetyltrimethylammonium bromide.

In an embodiment of the present invention, the aromatic hydrocarbon reacted with the ionic surfactant and the aromatic hydrocarbon washed with the white solid are the same, and the aromatic hydrocarbon includes but is not limited to one or more of toluene, ethylbenzene, benzene, and xylene.

In one embodiment of the invention, the ionic surfactant and the aromatic hydrocarbon are mixed and then placed in heat conducting oil to be heated, the heating temperature is 50-150 ℃, and the stirring is carried out for 30-480 min at the same time until the ionic surfactant is completely dissolved in the aromatic hydrocarbon, so that a colorless transparent solution is obtained.

In one embodiment of the present invention, the anionic polymerization catalyst is a catalyst used in perfluoropolyether synthesis, including but not limited to one or more of potassium fluoride or cesium fluoride.

In one embodiment of the invention, the anionic polymerization catalyst is added into the colorless transparent solution under the condition of keeping the temperature unchanged, and the mixture is stirred for 30min to 480min to obtain the anionic polymerization catalyst coated by the surfactant.

In one embodiment of the invention, the washed white solid is placed in a vacuum drying oven at 50-150 ℃ and dried in vacuum for 120-480 min to obtain the dried white solid, namely the surface modified anionic polymerization catalyst.

In one embodiment of the present invention, the method further comprises measuring the moisture absorption resistance of the surface-modified anionic polymerization catalyst, wherein the measuring comprises exposing the surface-modified anionic polymerization catalyst to an indoor environment at a humidity of 50-80, accurately weighing the mass at certain intervals for 24-72 hours, and recording the mass weighed at each weighing.

Compared with the prior art, the technical scheme of the invention has the following innovation points:

1: anionic or cationic surfactants such as sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and hexadecyl trimethyl ammonium bromide are used as modifiers to carry out surface modification on the anionic polymerization catalyst. The ionic end of the surfactant is adsorbed on the outer surface of the anionic polymerization catalyst, and the hydrophobic chain of the surfactant is exposed in the external environment to create a hydrophobic microenvironment. The modified anionic polymerization catalyst has good moisture absorption resistance.

2: dissolving the above surfactant in dry aromatic solvent such as benzene, toluene, ethylbenzene, xylene, etc. under heating, adding anionic polymerization catalyst, and stirring at 50-150 deg.C for reaction for a period of time (30min-480min) to promote full adsorption of surfactant molecules on the outer surface of anionic polymerization catalyst.

3: the concentration of the above-mentioned surfactant in the aromatic hydrocarbon solvent is higher than the critical micelle concentration, and the surfactant forms reversed micelles in the aromatic hydrocarbon solvent, i.e., the polar end of the surfactant faces inwards, and the hydrophobic end faces outwards to form micelle clusters. For example, sodium dodecylbenzenesulfonate is present in toluene in a concentration range of 5% to 30%.

In the synthesis of perfluoropolyethers from tetrafluorooxetanes, potassium fluoride or cesium fluoride is generally used as an anionic polymerization catalyst. Potassium fluoride and cesium fluoride are very hygroscopic and absorb moisture in the air sufficiently to have a significant adverse effect on the anionic polymerization of tetrafluorooxetane when weighed and dosed. To eliminate this effect, it is generally necessary to use an anhydrous and oxygen-free environment to avoid introducing moisture into the reaction system, which imposes high requirements on the test equipment and operators. Furthermore, it is necessary to dry potassium fluoride or cesium fluoride before the anion polymerization test, while avoiding sintering of cesium fluoride or potassium fluoride as much as possible. This has a serious adverse effect on potassium fluoride or cesium fluoride initiated anionic polymerization of tetrafluorooxetanes.

The invention provides a method for modifying the surface of potassium fluoride or cesium fluoride by using an ionic surfactant, which comprises a cationic surfactant and an anionic surfactant. The ionic terminal of the ionic surfactant is adsorbed on the outer surface of potassium fluoride or cesium fluoride, and the hydrophobic long chain of the ionic surfactant is exposed to the external environment. The modified potassium fluoride or cesium fluoride is coated with a hydrophobic layer on the outer surface, so that the modified potassium fluoride or cesium fluoride has good moisture absorption resistance, and the quality of the modified potassium fluoride or cesium fluoride is basically kept unchanged after the modified potassium fluoride or cesium fluoride is exposed in the air for 72 hours. This provides convenient conditions for the use of potassium fluoride or cesium fluoride in the anionic polymerization of tetrafluorooxetanes and is advantageous for maintaining reproducibility among different batches of anionic polymerization.

Drawings

In order to make the technical problems solved by the present invention, the technical means adopted and the technical effects obtained more clear, the following will describe in detail the embodiments of the present invention with reference to the accompanying drawings. It should be noted, however, that the drawings described below are only illustrations of exemplary embodiments of the invention, from which other embodiments can be derived by those skilled in the art without inventive step.

FIG. 1 is the X-ray diffraction fringe pattern of potassium fluoride, sodium dodecylbenzenesulfonate and modified potassium fluoride.

FIG. 2 is an infrared spectrum of potassium fluoride, sodium dodecylbenzenesulfonate and modified potassium fluoride.

Detailed Description

Exemplary embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention may be embodied in many specific forms, and should not be construed as limited to the embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. The structures, properties, effects or other characteristics described in a certain embodiment may be combined in any suitable manner in one or more other embodiments, while still complying with the technical idea of the invention.

In describing particular embodiments, specific details of structures, properties, effects, or other features are set forth in order to provide a thorough understanding of the embodiments by one skilled in the art. However, it is not excluded that a person skilled in the art may implement the invention in a specific case without the above-described structures, performances, effects or other features.

The flow chart in the drawings is only an exemplary flow demonstration, and does not represent that all the contents, operations and steps in the flow chart are necessarily included in the scheme of the invention, nor does it represent that the execution is necessarily performed in the order shown in the drawings. For example, some operations/steps in the flowcharts may be divided, some operations/steps may be combined or partially combined, and the like, and the execution order shown in the flowcharts may be changed according to actual situations without departing from the gist of the present invention.

The block diagrams in the figures generally represent functional entities and do not necessarily correspond to physically separate entities. I.e. these functional entities may be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different network and/or processing unit devices and/or microcontroller devices.

The same reference numerals denote the same or similar elements, components, or parts throughout the drawings, and thus, a repetitive description thereof may be omitted hereinafter. It will be further understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, or sections, these elements, components, or sections should not be limited by these terms. That is, these phrases are used only to distinguish one from another. For example, a first device may also be referred to as a second device without departing from the spirit of the present invention. Furthermore, the term "and/or", "and/or" is intended to include all combinations of any one or more of the listed items.

Anionic polymerization catalysts such as potassium fluoride and cesium fluoride are highly hygroscopic and agglomerate when exposed to air, on the one hand, polar water molecules are brought into the anionic polymerization reaction system, and adverse effects are caused on the polymerization reaction; on the other hand, potassium fluoride or cesium fluoride absorbs moisture and agglomerates to cause that the specific surface area of the catalyst is greatly reduced, thereby influencing the catalytic activity of the catalyst.

The invention adopts the ionic surfactant to carry out surface modification on potassium fluoride or cesium fluoride, the ionic terminal of the ionic surfactant is adsorbed on the outer surface of the potassium fluoride or cesium fluoride, the hydrophobic chain segment of the ionic surfactant forms a hydrophobic coating layer on the outer surface of the potassium fluoride or cesium fluoride, water molecules are prevented from diffusing to the inner core of potassium fluoride or cesium fluoride particles, and the moisture absorption capacity of the potassium fluoride or cesium fluoride is reduced. When the modified potassium fluoride or cesium fluoride is applied to anionic polymerization, a large amount of moisture is not absorbed due to short exposure to air during weighing and charging. Therefore, the efficiency and repeatability of the anionic polymerization reaction can be greatly improved.

The present invention provides a method for surface modifying an anionic polymerization catalyst, such as potassium fluoride or cesium fluoride, to increase the resistance of potassium fluoride or cesium fluoride to moisture absorption, comprising the steps of:

step 1: 5-30g of ionic surfactant, including but not limited to sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, cetyl trimethyl ammonium bromide, was added to a three necked round bottom flask. Then, 100g of a dried aromatic solvent, including but not limited to toluene, ethylbenzene, benzene, xylene, is added. Then the three-mouth flask is placed in heat-conducting oil at 50-150 ℃ to be heated, and after stirring reaction is carried out for 30-480 min, the ionic surfactant is completely dissolved in the aromatic hydrocarbon solvent to form a completely transparent solution.

Step 2: and (2) keeping the transparent solution in the step (1) at the original temperature, then quickly adding potassium fluoride or cesium fluoride powder (1-20g), keeping at a constant temperature, continuously stirring and reacting for 30-480 min to obtain the surfactant-coated potassium fluoride and cesium fluoride.

And step 3: filtration was carried out at the temperature described in step 2, and the white solid was collected and then washed 5 times with the same aromatic hydrocarbon solvent. And (3) putting the washed white solid into a vacuum drying oven at 50-150 ℃, and carrying out vacuum drying for 120-480 min. Finally, the dried white solid is collected into a glass bottle, and the glass bottle is plugged with a stopper and stored for later use.

And 4, step 4: and (3) taking a small amount of the catalyst prepared in the step (3), exposing the catalyst to an indoor environment, accurately weighing the catalyst at a certain interval with the humidity of 50-80, and continuing for 24-72 hours. It was thus judged whether the prepared catalyst had good moisture absorption resistance.

The invention will be further illustrated with reference to specific examples below:

comparative example 1

1g of analyzed potassium fluoride powder purchased from Shanghai Aladdin Biotechnology Co., Ltd was spread in a cylindrical glass bottle having a diameter of 2.5cm and a height of 7cm, and placed in an open room. The room temperature is 20-25 deg.C, and the humidity is 65%. After 24 hours of standing, the weight of the potassium fluoride powder in the glass bottle was increased by 0.05 g.

Comparative example 2

2.5g of the anionic surfactant sodium dodecylbenzenesulfonate was added to a three-necked round-bottomed flask, followed by 100g of dried pyridine. Then the three-neck flask is placed in heat-conducting oil at 50 ℃ to be heated, the mixture is stirred and reacts for 60min, and the sodium dodecyl benzene sulfonate is completely dissolved in the pyridine to form a completely transparent solution.

Then, 2.006g of potassium fluoride powder analyzed and purchased from Shanghai Aladdin Biotechnology Ltd was added to the above solution and reacted with stirring at 50 ℃ for 180 min. The pyridine was then evaporated to completion by distillation under reduced pressure. Finally, the obtained solid product is placed in a vacuum drying oven at 80 ℃ and is dried for 360min in vacuum. The dried modified potassium fluoride powder was spread in a cylindrical glass bottle having a diameter of 2.5cm and a height of 7cm, and placed in an indoor environment with the opening. The room temperature is 20-25 deg.C, and the humidity is 65%. After 24 hours of standing, the weight of the potassium fluoride powder in the glass bottle is increased by 0.03 g.

Example 1

20.001g of the anionic surfactant sodium dodecylbenzenesulfonate was charged into a three-necked round-bottomed flask, followed by 100.181g of dried toluene. Then the three-neck flask is placed in heat-conducting oil at 80 ℃ to be heated, the mixture is stirred and reacts for 180min, and the sodium dodecyl benzene sulfonate is completely dissolved in the toluene to form a completely transparent solution.

Then, 5.000g of analyzed potassium fluoride powder purchased from Shanghai Aladdin Biotechnology Ltd was added to the above solution, and reacted with stirring at 80 ℃ for 180 min. Then, the mixture was filtered at 80 ℃ to collect a white solid, and the white solid was washed with toluene 5 times. The washed white solid was placed in a vacuum oven at 80 ℃ and dried under vacuum for 480 min.

The dried modified potassium fluoride powder was spread in a cylindrical glass bottle having a diameter of 2.5cm and a height of 7cm, and placed in an indoor environment with the opening. The room temperature is 20-25 deg.C, and the humidity is 65%. After standing for 24 hours, the quality of the potassium fluoride powder in the glass bottle is not changed.

Example 2

4.99g of the anionic surfactant sodium dodecylbenzenesulfonate was charged into a three-necked round-bottomed flask, and then 99.93g of dried toluene was added. Then the three-neck flask is placed in heat-conducting oil at 80 ℃ to be heated, the mixture is stirred and reacts for 180min, and the sodium dodecyl benzene sulfonate is completely dissolved in the toluene to form a completely transparent solution.

Then, 4.98g of analyzed potassium fluoride powder purchased from Shanghai Aladdin Biotechnology Ltd was added to the above solution, and reacted with stirring at 80 ℃ for 180 min. Then, the mixture was filtered at 80 ℃ to collect a white solid, and the white solid was washed with toluene 5 times. The washed white solid was placed in a vacuum oven at 80 ℃ and dried under vacuum for 480 min.

0.331g of dried modified potassium fluoride powder was spread in a cylindrical glass bottle having a diameter of 2.5cm and a height of 7cm, and placed in an open room. The room temperature is 20-25 deg.C, and the humidity is 65%. After standing for 24 hours, the mass of the potassium fluoride powder in the glass bottle is 0.331 g; after standing for 48 hours, the mass of the potassium fluoride powder in the glass bottle is 0.331 g; after standing for 72 hours, the amount of potassium fluoride powder in the glass bottle was 0.332 g.

As can be seen from the X-ray diffraction fringe patterns of the potassium fluoride, the sodium dodecyl benzene sulfonate and the modified potassium fluoride in figure 1, the modification process does not cause obvious changes to the crystal form of the potassium fluoride.

It can be seen from the infrared spectra of potassium fluoride, sodium dodecylbenzenesulfonate and modified potassium fluoride in fig. 2 that sodium dodecylbenzenesulfonate is indeed coated on the outer surface of the potassium fluoride particles.

Example 3

A three-necked flask having a volume of 1000mL was placed in the low-temperature tank, and a magnetic stirrer was added thereto to conduct magnetic stirring. Then, 6g of the surface-modified anionic polymerization catalyst (prepared according to the procedure of example 2) and 600mL of diethylene glycol dimethyl ether were added, stirring was switched on and the reaction medium was cooled to-10 ℃. Then 200g of tetrafluorooxetane was dropped into the reaction system using a constant pressure dropping funnel, followed by reaction at-10 ℃ for 12 hours. After the reaction is finished, removing diethylene glycol dimethyl ether by reduced pressure distillation to finally obtain the tetrafluoro oxetane oligomer with the polymerization degree of 25-30.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

It should be noted that, for simplicity of description, the above-mentioned method embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present invention is not limited by the order of acts, as some steps may occur in other orders or concurrently in accordance with the invention. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and modules referred to are not necessarily required by the invention.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.