阅读说明：本技术 一种细菌纤维素纳米晶/手性偶氮苯复合膜及其制备方法 (Nanocrystalline/chiral azobenzene composite membrane of a kind of bacteria cellulose and preparation method thereof ) 是由 王斌 段承良 李金鹏 葛洲 陈克复 曾劲松 徐峻 高文花 于 2019-07-15 设计创作，主要内容包括：本发明公开了一种细菌纤维素纳米晶/手性偶氮苯复合膜及其制备方法。该方法包括：硫酸法水解细菌纤维素得到细菌纤维素纳米晶悬浮液,化学合成具有较长联苯刚性链的手性偶氮苯,将制得的细菌纤维素纳米晶悬浮液与手性偶氮苯溶液混合,再将混合均匀后的悬浮液在温度为30℃、湿度为60%的条件下蒸发,使其自组装成膜,得到细菌纤维素纳米晶体/手性偶氮苯复合膜。本发明提供的制备方法,所采用的蒸发诱导自组装方法操作方便,条件操控简单,可控性好。所述细菌纤维素纳米晶体/手性偶氮苯复合膜在光的调控下不仅会有颜色的变化,还会有形貌的变化,可作为功能膜材料应用在光子器件、智能显示、光敏器件等多个领域。(The invention discloses nanocrystalline/chiral azobenzene composite membranes of a kind of bacteria cellulose and preparation method thereof.This method comprises: sulfuric acid process hydrolytic bacteria cellulose obtains bacteria cellulose nanocrystal suspension, chemical synthesis has the chiral azobenzene of longer biphenyl rigid chain, bacteria cellulose nanocrystal suspension obtained is mixed with chiral azo benzole soln, suspension after mixing is evaporated under conditions of temperature is 30 DEG C, humidity is 60% again, so that its self assembly is formed a film, obtains bacteria cellulose nanocrystal/chirality azobenzene composite membrane.Preparation method provided by the invention, used evaporation-induced self-assembly method is easy to operate, and condition manipulation is simple, and controllability is good.Bacteria cellulose nanocrystal/chirality azobenzene the composite membrane coloured can not only change under the regulation of light, also have the variation of pattern, can be used as functional film material and apply in multiple fields such as photonic device, intelligent display, light-sensitive devices.)

1. a kind of preparation method of nanocrystalline/chiral azobenzene composite membrane of bacteria cellulose, which is characterized in that including walking as follows It is rapid:

(1) bacteria cellulose is mixed with concentrated sulfuric acid solution, reaction is then hydrolyzed under stirring, water, mixing is added Uniformly, emulsion is obtained；

(2) step (1) emulsion is subjected to centrifugal treating, takes upper layer suspension；

(3) step (2) described suspension is poured into and carries out dialysis treatment in bag filter, until suspension is in neutrality, concentration is obtained Cellulose nanocrystal liquid suspension；

(4) by S-2, bis- ((E)-(4- (octyloxy) phenyl) diazenyl) -1, the 1'- dinaphthalenes of 2'- are added to the water, and are uniformly mixed, Obtain chiral azo benzole soln；

(5) step (3) the Cellulose nanocrystal liquid suspension is mixed with step (4) the chiral azo benzole soln, is stirred Uniformly, mixed solution is obtained, is ultrasonically treated, it is nanocrystalline/chiral even to obtain the bacteria cellulose for evaporation-induced self-assembly film forming Pyridine composite membrane.

2. preparation method according to claim 1, which is characterized in that the quality percentage of step (1) described concentrated sulfuric acid solution Specific concentration is 55wt%-70wt%；The mass ratio of the bacteria cellulose and concentrated sulfuric acid solution is 1:(15-20).

3. preparation method according to claim 1, which is characterized in that step (1) the stirring speed under stirring Rate is 250-350r/min；The temperature of the hydrolysis is 40-60 DEG C, and the time of hydrolysis is 40-60min.

4. preparation method according to claim 1, which is characterized in that the volume of step (1) concentrated sulfuric acid solution and water Than for 1:10-15.

5. preparation method according to claim 1, which is characterized in that the revolving speed of step (2) described centrifugal treating is 8000- 10000r/min, the time of centrifugal treating are 8-12min.

6. preparation method according to claim 1, which is characterized in that the molecular cut off of step (3) described bag filter is 14000-16000；The time of the dialysis treatment is 10-14 days；In step (3) the Cellulose nanocrystal liquid suspension, The concentration of the Cellulose nanocrystal is 1.1wt%-1.4wt%.

7. preparation method according to claim 1, which is characterized in that the quality of step (4) the chiral azo benzole soln Percent concentration is 1wt%-2wt%.

8. preparation method according to claim 1, which is characterized in that step (5) the Cellulose nanocrystal liquid suspension Mass ratio with chiral azo benzole soln is 30:(1-5).

9. preparation method according to claim 1, which is characterized in that the supersonic frequency of step (5) described ultrasonic treatment is 20-40KHz, the time of ultrasonic treatment are 10-20min；The temperature of ultrasonic treatment is 0-10 degrees Celsius；The evaporation is induced from group The temperature for dressing up film is 25-40 DEG C, and the humidity of evaporation-induced self-assembly film forming is 40%-60%, evaporation-induced self-assembly film forming Time is 72-96h.

10. a kind of nanocrystalline/chiral azobenzene of bacteria cellulose as made from claim 1-9 described in any item preparation methods Composite membrane.

Technical field

The invention belongs to the fields of functional film material, and in particular to a kind of nanocrystalline/chiral azobenzene of bacteria cellulose is multiple Close film and preparation method thereof.

Background technique

Bacteria cellulose is a kind of tencel that microorganism obtains after processing, has three-dimensional space net structure, height Characteristics, these excellent characteristics such as crystallinity, highly-breathable, good biocompatibility, high mechanical strength, biological degradability be good make Bacteria cellulose is widely used in each research field.The Cellulose nanocrystal that bacteria cellulose is prepared through sulfuric acid process, specific Under the conditions of can form nematic liquid crystal and form chiral nematic phase liquid crystal, this characteristic be bacteria cellulose liquid crystal at Film field provides many possibilities.

Chiral azobenzene material has unique design feature, as azobenzene chiral molecules can be under the irradiation of light Reversible cis-trans isomerization reaction is carried out, the significant changes of chiral molecules structure can be caused, or even the variation of shape can be caused, Therefore, the attention of scientific research personnel is increasingly obtained.The azobenzene chiral molecules of different structure, corresponding helical twisting power Difference, according to this feature, azobenzene chiral molecules is often introduced into field of liquid crystals by people, for example, by azobenzene chirality Molecule is introduced into formation chiral nematic phase liquid crystal in nematic phase, and the screw pitch in liquid crystal system can be because of azobenzene structure or doping concentration It is different and generate very big variation, it is thus possible to regulate and control liquid crystal by changing illumination condition.

Cholesteric liquid crystal has great importance in scientific research due to its unique helical structure.Regulate and control by light It is long-range, real-time, non-contact the advantages that, the research of optical Response cholesteric liquid crystal is by high praise.In patent (application number CN201510773696.6 it) in " a kind of preparation method of Cellulose nanocrystal body cholesteryl liquid crystal texture anti-fake mark ", uses Be that cellulose containing chiral radicals itself is self-assembly of cholesteric liquid crystal, the cholesteric liquid crystal of this formation is not easy to adjust Screw pitch is saved, is regulated and controled to be not easy liquid crystal.Therefore, in the research of cholesteric liquid crystal of the invention, bacteria cellulose is made For nematic phase matrix, adds chiral molecules and form cholesteric liquid crystal, it, can be simply fast by changing the doping concentration of chiral molecules Speed regulates and controls liquid crystal.

Summary of the invention

In order to overcome deficiencies of the prior art, the object of the present invention is to provide a kind of bacteria cellulose nanometers Brilliant/chiral azobenzene composite membrane and preparation method thereof.

Cholesteric phase is prepared in bacteria cellulose and chiral azobenzene self assembly the primary purpose of the present invention is that providing one kind The method of liquid crystal.

Another object of the present invention is to provide by the controllable liquid crystal film of light obtained by the above method, applied The fields such as photonic device, intelligent display.

The purpose of the present invention is realized at least through one of following technical solution.

A kind of preparation method of nanocrystalline/chiral azobenzene composite membrane of bacteria cellulose provided by the invention, including it is as follows Step:

(1) bacteria cellulose is mixed with concentrated sulfuric acid solution, reaction is then hydrolyzed under stirring, water is added, It is uniformly mixed, obtains emulsion；

(2) step (1) emulsion is subjected to centrifugal treating, takes the suspension on upper layer；

(3) step (2) described suspension is poured into and carries out dialysis treatment in bag filter, until suspension is in neutrality, concentration, Obtain Cellulose nanocrystal liquid suspension；

(4) (chemical synthesis is can be used into bis- ((E)-(4- (octyloxy) phenyl) the diazenyl) -1,1'- dinaphthalenes of S-2,2'- Method synthesis) be added to the water, be uniformly mixed, obtain chiral azo benzole soln；

(5) step (3) the Cellulose nanocrystal liquid suspension is mixed with step (4) the chiral azo benzole soln, Mechanical stirring is uniform, obtains mixed solution, ultrasonic treatment, and evaporation-induced self-assembly film forming obtains the bacteria cellulose nanometer Brilliant/chiral azobenzene composite membrane.

Further, the mass percent concentration of step (1) described concentrated sulfuric acid solution is 55wt%-70wt%；It is described thin The mass ratio of fungin and concentrated sulfuric acid solution is 1:(15-20).

Further, step (1) stirring rate under stirring is 250-350r/min；The hydrolysis Temperature be 40-60 degrees Celsius, time of hydrolysis is 40-60min.

Further, the volume ratio of step (1) concentrated sulfuric acid solution and water is 1:10-15.

Further, the revolving speed of step (2) described centrifugal treating is 8000-10000r/min, and the time of centrifugal treating is 8-12min。

Further, the molecular cut off of step (3) described bag filter is 14000-16000；The dialysis treatment when Between be 10-14 days.

Preferably, the mode of step (3) described concentration includes anti-dialysis concentration, the bag filter containing suspension can be soaked It steeps and carries out concentration in the polyglycol solution that mass percent concentration is 15wt%.

Further, in step (3) the Cellulose nanocrystal liquid suspension, the concentration of the Cellulose nanocrystal is 1.1wt%-1.4wt%.

Further, step (3) the Cellulose nanocrystal liquid suspension is prepared using the method for sulphuric acid hydrolysis.

Further, the preparation of step (3) the Cellulose nanocrystal liquid suspension includes: to add Nano bacteria cellulose Enter into sulfuric acid, hydrolyzed under conditions of heating and stirring, a large amount of deionized water is added after hydrolysis and terminates reaction, will To white solution be centrifuged, dialysed, remove remaining sulfuric acid, then anti-dialysis is concentrated to get bacteria cellulose nanometer crystalline suspension Liquid.

Further, the mass percent concentration of step (4) the chiral azo benzole soln is 1wt%-2wt%.

Further, chiral azobenzene (bis- ((E)-(4- (octyloxy) phenyl) diazenyls) -1,1'- of S-2,2'- Dinaphthalene) preparation include: that S- (-) -1,1'- dinaphthalene -2,2'- diamines is dissolved in hydrochloric acid solution, it is cooling after by sodium nitrite Solution is slowly dropped in above-mentioned solution, and after being added dropwise to complete, obtained solution is added drop-wise in phenol-NaOH- water mixed liquid； After the reaction was completed, it is acidified with the dilute hydrochloric acid that 30mL concentration is 1wt%, filtering；Precipitating is washed after the completion of filtering, is dried to obtain thick Product obtains intermediate through silica gel column chromatography；Above-mentioned intermediate, a bromooctane, DMF are sequentially added in round-bottomed flask, through stirring After mixing dissolution, potassium carbonate, heating, reflux a period of time is being added；To after reaction, water be added into reaction, it is cooled to room Temperature, ethyl acetate extraction, collects organic layer, saturated common salt water washing, rotary evaporation obtains yellow solid product, through silica gel column layer Analysis obtains target product chirality azobenzene.(bibliography: Xie Yu have switch feature azobenzene chiral molecules preparation and Flexible Displays performance study [D] Beijing University of Chemical Technology, 2014.)

Further, it is 1-3mol/L, sodium nitrite that every gram of S- (-) -1,1'- dinaphthalene -2,2'- diamines, which corresponds to concentration of hydrochloric acid, Concentration is 5-7wt%, and phenol-NaOH- water molal weight ratio is 1:3:114；The corresponding bromooctane of every mole of intermediate is 4- 5mol, the amount of n,N-Dimethylformamide (DMF) are 50-80ml, and the amount of potassium carbonate substance is 8-10mmol；The mixing speed For 200-300r/min, it is warming up to 80-90 DEG C, return time 10-12h after potassium carbonate is added, water 20- is added at the end of reaction 40ml。

Preferably, the rotating evaporation temperature is 50-60 DEG C, and rotary evaporation pressure is 110-140mbar, rotary evaporation speed Degree is 40-50r/min, rotary evaporation time 4-6h.

Further, the mass ratio of step (5) the Cellulose nanocrystal liquid suspension and chiral azo benzole soln is 30: (1-5)。

Preferably, the mass ratio of step (5) the Cellulose nanocrystal liquid suspension and chiral azo benzole soln be 30:1, 30:2,30:3,30:4 or 30:5.

Preferably, the rate of step (5) described stirring is 250-400r/min, the time 15-35min of stirring.

Further, the supersonic frequency of step (5) described ultrasonic treatment is 20-40KHz, and the time of ultrasonic treatment is 10- 20min；The temperature of ultrasonic treatment is 0-10 DEG C；The temperature of the evaporation-induced self-assembly film forming is 25-40 DEG C, and evaporation induction is certainly The humidity of assembling film forming is 40-60%, and the time of evaporation-induced self-assembly film forming is 72-96h.

It is compound that the present invention provides a kind of nanocrystalline/chiral azobenzene of bacteria cellulose as made from above-mentioned preparation method Film.

Nanocrystalline/chiral azobenzene composite membrane of a kind of bacteria cellulose provided by the invention comprising bacteria cellulose is received Bis- ((E)-(4- (octyloxy) phenyl) diazenyl) -1, the 1'- dinaphthalenes (chiral azobenzene) of meter Jing and S-2,2'-, the bacterium The mass values of Cellulose nanocrystal and chiral azobenzene are 6-30:1, and the inside of the composite membrane is in cholesteric liquid crystal structure.

Compared with prior art, the invention has the advantages that and the utility model has the advantages that

(1) preparation method provided by the invention, selection bacteria cellulose are raw material, and source is natural, and purity is high is at low cost Honest and clean, production process is environmentally protective.Bacteria cellulose can form nematic phase, introduce chiral molecules (chiral azo on this basis Benzene) form cholesteric liquid crystal；This, more can be simply directly by changing hand compared with the cholesteric liquid crystal that cellulose itself is formed Property molecular dopant concentration adjust screw pitch, and then regulate and control liquid crystal film macroshape and interior microscopic construction；

(2) preparation method provided by the invention, the chiral azobenzene used (bis- ((E)-(4- (pungent oxygen of S-2,2'- Base) phenyl) diazenyl) -1,1'- dinaphthalene) there is axial chirality dinaphthalene group, the azobenzene group of photo-isomerisable, long is soft Property alkyl chain, when inducing cholesteric liquid crystal, axial chirality dinaphthalene group provides biggish spiral inducibility, azobenzene group The spatial configuration that cis-trans isomerism changes photoswitch molecule can occur under light illumination, long flexible chain makes molecule steric-configuration photic It is big to change amplitude in isomate process, it is strong to the disturbance ability of liquid crystal molecule around；

(3) preparation method provided by the invention prepares liquid crystal film, operation side using evaporation-induced self-assembly mode Just, condition manipulation is simple, and controllability is good.

Detailed description of the invention

Fig. 1 is the preparation flow figure that embodiment 1-5 prepares chiral nematic phase liquid crystal.

Fig. 2 is nanocrystalline/chiral azo of bacteria cellulose described in the nanocrystalline thread-like texture of bacteria cellulose and embodiment 1 Benzene composite membrane observing effect figure under petrographic microscope.

Specific embodiment

Specific implementation of the invention is described further below in conjunction with attached drawing and example, but implementation and protection of the invention It is without being limited thereto.If it is existing to be that those skilled in the art can refer to it is noted that there is the not special process of detailed description below Technology realize or understand.Reagents or instruments used without specified manufacturer, be considered as can by it is commercially available be commercially available it is normal Advise product.

The preparation method of chirality azobenzene used in the following embodiment includes the following steps: 1g S- (-) -1,1'- Dinaphthalene -2,2'- diamines is dissolved in the hydrochloric acid solution that 20ml concentration is 2mol/L, and 0 DEG C is cooled in ice-water bath；In stirring bar 6wt% sodium nitrite solution is added drop-wise in above-mentioned solution under part, after being added dropwise to complete, obtained solution is added drop-wise to phenol- NaOH- water quality is than in the mixed liquor for 1:3:114；It after the reaction was completed, is the acidification of 1wt% dilute hydrochloric acid solution with 30mL concentration, Filtering；Precipitating is washed after the completion of filtering, crude product is dried to obtain, obtains orange/yellow solid product (4,4'- through silica gel column chromatography ((1E, 1'E)-((S)-(1,1'- dinaphthalene) -2,2'- diyl) two (diazo alkene -2,1- diyl)) biphenol)；In round-bottomed flask In sequentially add above-mentioned 0.5g orange/yellow solid product, mono- bromooctane of 1g, 60ml n,N-Dimethylformamide (DMF), through stirring After mixing dissolution, 1.4g potassium carbonate is being added, is being warming up to 90 DEG C, flow back 12h；To after reaction, 35ml be added into reaction Water is cooled to room temperature, ethyl acetate extraction, collects organic layer, saturated common salt water washing, and rotary evaporation obtains yellow solid production Object obtains target product S-2 through silica gel column chromatography, bis- ((E)-(4- (octyloxy) phenyl) diazenyl) -1, the 1'- dinaphthalenes of 2'-, Yield is in 65%-75%.

The method that following embodiment prepares nanocrystalline/chiral azobenzene composite membrane of bacteria cellulose, related procedure can refer to Shown in Fig. 1.