CN116178764A - Starch/chitosan composite membrane and preparation method and application thereof - Google Patents

Starch/chitosan composite membrane and preparation method and application thereof Download PDF

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CN116178764A
CN116178764A CN202310284552.9A CN202310284552A CN116178764A CN 116178764 A CN116178764 A CN 116178764A CN 202310284552 A CN202310284552 A CN 202310284552A CN 116178764 A CN116178764 A CN 116178764A
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starch
chitosan
composite film
solution
titanium dioxide
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易苏
谭宇桓
曹斌
何为
谢向言
曹霞
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Hunan Institute of Engineering
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2303/00—Characterised by the use of starch, amylose or amylopectin or of their derivatives or degradation products
    • C08J2303/02—Starch; Degradation products thereof, e.g. dextrin
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2305/00—Characterised by the use of polysaccharides or of their derivatives not provided for in groups C08J2301/00 or C08J2303/00
    • C08J2305/08—Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2403/00—Characterised by the use of starch, amylose or amylopectin or of their derivatives or degradation products
    • C08J2403/02—Starch; Degradation products thereof, e.g. dextrin
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2405/00—Characterised by the use of polysaccharides or of their derivatives not provided for in groups C08J2401/00 or C08J2403/00
    • C08J2405/08—Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
    • C08K3/20—Oxides; Hydroxides
    • C08K3/22—Oxides; Hydroxides of metals
    • C08K2003/2237—Oxides; Hydroxides of metals of titanium
    • C08K2003/2241—Titanium dioxide
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K2201/00—Specific properties of additives
    • C08K2201/011—Nanostructured additives
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    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00—Use of pretreated ingredients
    • C08K9/04—Ingredients treated with organic substances
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00—Use of pretreated ingredients
    • C08K9/04—Ingredients treated with organic substances
    • C08K9/06—Ingredients treated with organic substances with silicon-containing compounds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W90/00—Enabling technologies or technologies with a potential or indirect contribution to greenhouse gas [GHG] emissions mitigation
    • Y02W90/10—Bio-packaging, e.g. packing containers made from renewable resources or bio-plastics

Abstract

The invention belongs to the technical field of antibacterial composite materials, and discloses a starch/chitosan composite film, a preparation method and application thereof. The method comprises the following steps: s1, dissolving starch in water for gelatinization, and then adding glycerol and NaCl and stirring to obtain starch gelatinized liquid; dissolving chitosan in acetic acid solution to obtain chitosan solution; mixing to obtain starch/chitosan gelatinized liquid; s2, nano titanium dioxide is formed into nano titanium dioxide suspension, ethanol solution is added, pH is regulated, and water bath stirring is carried outAdding a silane coupling agent solution for constant-temperature stirring reaction to obtain modified nano titanium dioxide; s3, adding the modified nano titanium dioxide into the starch/chitosan gelatinization liquid to obtain the starch/chitosan composite membrane. The invention adopts CTS and SDS surface modified M-Nano-TiO 2 For filling phase, the composite film is prepared by a blending method, so that the compactness of the composite film is improved, the integral mechanical property of the film is enhanced, and the film has better antibacterial property.

Description

Starch/chitosan composite membrane and preparation method and application thereof
Technical Field
The invention belongs to the technical field of antibacterial composite materials, and discloses a starch/chitosan composite film, a preparation method and application thereof.
Background
Along with the rapid development of industry, the application surface of the polymer composite material is wider, and the treatment of wastes becomes difficult, the traditional burying and burning methods can cause secondary pollution to the environment, and the recycling cost is higher, so that certain limitations exist, and the development of environment-friendly materials is an important subject in the fields of new polymer materials and engineering.
Starch is a hydrophilic colloid polymerized by polysaccharide, can be dried to form a film after gelatinization, has the performance similar to plastics, has the advantages of wide sources, low price, high film forming transparency, excellent bonding performance and the like, and is an ideal polymer film material. However, the inherent defects of plasticization caused by the crystal structure of starch molecules and the interaction of intermolecular hydrogen bonds lead to poor tensile strength and narrow processing window of a single starch film, and limit the application range of the single starch film.
In order to ensure that the starch film has better processing adaptability, the mechanical property and biological property of the film are often improved by a blending modification method in industrial production, for example, the nano SiO is researched in the prior art such as Zhao Xiya 2 Influence on mechanical properties of potato hydrogenated hydroxypropyl starch (POHS) film, nano SiO was found 2 The addition of the (C) can effectively improve the membrane integrity; ji and the like research the compatibility of chitosan and potato starch film, and find that the chitosan not only can improve the mechanical property of the film, but also has good compatibility. However, the composite film has poor compactness, resulting in insufficient mechanical properties and antibacterial propertyThe capacity is insufficient.
Disclosure of Invention
The invention aims to provide a starch/chitosan composite membrane, a preparation method and application thereof, which aim at solving the problems of poor compactness, poor mechanical property and insufficient antibacterial capability of the existing composite membrane, and adopts Chitosan (CTS) and sodium dodecyl benzene sulfonate (SDS) surface modified Nano titanium dioxide (M-Nano-TiO) as raw materials 2 ) Method for preparing M-Nano-TiO by blending for filling phase 2 The filled starch/chitosan three-component composite membrane improves the compactness of the composite membrane, enhances the integral mechanical property of the membrane and has better antibacterial property.
In order to achieve the above purpose, the technical scheme adopted in the application is as follows:
a preparation method of a starch/chitosan composite membrane comprises the following steps:
s1, dissolving starch in water to form a gelatinized compound, and then adding glycerol and NaCl and stirring to obtain a starch gelatinized liquid; dissolving chitosan in acetic acid solution to obtain chitosan solution; mixing the starch gelatinization liquid and the chitosan solution to obtain starch/chitosan gelatinization liquid;
s2, dispersing nano titanium dioxide and a surfactant in water, ultrasonically obtaining nano titanium dioxide suspension, adding an ethanol solution into the suspension, adjusting the pH value to 9, performing ultrasonic dispersion, then performing water bath stirring reaction, adding a silane coupling agent solution, performing constant-temperature stirring reaction, centrifuging, filtering and drying to obtain modified nano titanium dioxide;
and S3, adding the modified nano titanium dioxide into the starch/chitosan gelatinization liquid, stirring for reaction, performing vacuum degassing, pouring into a mould, repeatedly freezing and thawing for 3 times, and drying to obtain the starch/chitosan composite membrane.
Preferably, in S1, the mass ratio of the starch to the water is 1-2:25-30, the gelatinization temperature is 90 ℃, the addition amount of the glycerol is 25-27% of the volume of the gelatinized substance, and the addition amount of the NaCl is 4-6% of the volume of the gelatinized substance.
Preferably, in S1, the mass volume ratio of the chitosan to the acetic acid solution is 0.2-0.4 g:7-12 mL, and the volume fraction of the acetic acid solution is 2%.
Preferably, in S1, the volume ratio of the starch gelatinisation solution to the chitosan solution is 3-5:2-5.
Preferably, in S2, the mass ratio of the nano titanium dioxide to the surfactant to the water is 1.5-2:0.3-0.5:90-100, and the surfactant is one of sodium dodecyl benzene sulfonate, tween 20 or span 80.
Preferably, in S2, the volume ratio of the suspension to the ethanol solution is 2-4:1-3, the ethanol solution is prepared by ethanol and water according to the volume ratio of 1:1, the pH is regulated by adopting ammonia water, the temperature of the water bath stirring reaction is 80-85 ℃, and the time is 20-25 min;
the volume ratio of the silane coupling agent solution to the suspension is 10:1, and the silane coupling agent solution is prepared from a silane coupling agent KH550 and water according to the mass volume ratio of 0.3g to 10 mL.
Preferably, in S3, the addition amount of the modified nano titanium dioxide is 0.1% of the mass of the starch/chitosan gelatinized liquid, and the stirring reaction time is 2 hours.
Preferably, in S3, the repeated freezing and thawing mode is to freeze at-18 ℃ for 12 hours and then defrost.
In addition, the invention also provides the starch/chitosan composite membrane prepared by the preparation method.
In addition, the application of the starch/chitosan composite film in preparing antibacterial products.
Compared with the prior art, the invention has the beneficial effects that:
the invention takes starch as raw material, adopts Chitosan (CTS) and Nano titanium dioxide (M-Nano-TiO) surface modified by sodium dodecyl benzene sulfonate (SDS) 2 ) Method for preparing M-Nano-TiO by blending for filling phase 2 The filled starch/chitosan three-component composite membrane improves the compactness of the composite membrane, enhances the integral mechanical property of the membrane and has better antibacterial property.
Drawings
FIG. 1 is a graph showing the mechanical properties of comparative examples 1-5 starch/CTS composite films of the present invention;
FIG. 2 is an infrared spectrum of the composite films of example 1, comparative example 2 and comparative example 5 of the present invention;
FIG. 3 is a microstructure of the composite film of example 1 and comparative example 2 of the present invention;
FIG. 4 is an XRD pattern of composite films of example 1, comparative example 2 and comparative example 5 of the present invention;
fig. 5 shows the bacteriostatic properties of inventive example 1 and comparative example 2.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the data in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that the technical terms used in the present invention are only for describing specific embodiments, and are not intended to limit the scope of the present invention, and various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention may be purchased commercially or prepared by existing methods unless otherwise specifically described.
Example 1
A preparation method of a starch/chitosan composite membrane comprises the following steps:
s1, weighing 4.0g of starch, dissolving in 100mL of distilled water, slowly heating to 90 ℃, stirring at a constant speed of 150r/min to gelatinize the starch to form a gelatinized material, adding 25% of glycerol and 5% of NaCl according to the volume ratio, and stirring uniformly to obtain a starch gelatinized liquid;
0.6g of Chitosan (CTS) was weighed and added to 20mL of 2% acetic acid (CH) 3 COOH) to obtain a chitosan solution with a mass fraction of 3%;
mixing the starch gelatinization liquid and the chitosan solution according to the volume ratio of 4:3 to obtain starch/chitosan gelatinization liquid;
s2, adding titanium dioxide into a ball milling tank, performing reaction ball milling by adopting a SPEX8000-230 vibratory ball mill according to the ball material mass ratio of 10:1,ball milling for 60min, repeating for three times to obtain nanometer titanium dioxide (Nano-TiO) 2 ) Drying the powder in a vacuum drying oven for later use;
2.0g of Nano-TiO is weighed respectively 2 And 0.5g of sodium dodecyl benzene sulfonate (SDS), adding into 100mL of distilled water, stirring at room temperature uniformly, and performing ultrasonic dispersion for 30min to obtain Nano-TiO 2 A suspension; adding 50mL of ethanol solution prepared by ethanol and water in a volume ratio of 1:1 into the suspension, then dropwise adding ammonia water, regulating the pH value to 9, performing ultrasonic dispersion at room temperature for 15min, transferring into a 250mL three-neck flask, and stirring at constant temperature and constant speed in a water bath at 80 ℃ for 20min to obtain Nano-TiO 2 Uniformly dispersing in the mixed solution, slowly dripping 10mL of silane coupling agent solution prepared by silane coupling agent KH550 and water according to the mass-volume ratio of 0.3g to 10mL, rapidly stirring at constant temperature for reaction for 2h, centrifuging at 3000r/min for 8min after the reaction is finished, filtering to obtain a precipitate, and drying at constant temperature of 80 ℃ to obtain the modified Nano-TiO 2 A powder;
s3, adding modified Nano-TiO2 powder into the starch/chitosan gelatinization liquid, wherein the addition amount of the modified Nano-TiO2 powder is 0.1 percent of the mass of the starch/chitosan gelatinization liquid, magnetically stirring for 2 hours, vacuum degassing and defoaming at-0.1 MPa, pouring into a PTFE mold, putting into a freezing chamber, freezing at-18 ℃ for 12 hours, taking out, freezing for 12 hours after complete thawing, repeatedly freezing and thawing for 3 times, naturally airing at room temperature, drying in a vacuum drying oven at 45 ℃, and uncovering a film to obtain the starch/CTS/M-Nano-TiO 2 Composite film with thickness of (0.06+ -0.01) mm, named 4-starch/3-CTS/0.1% M-Nano-TiO 2 。
Example 2
The preparation method of the starch/chitosan composite membrane is basically the same as that of example 1, except that the volume ratio of the starch gelatinization liquid to the chitosan solution in S1 is 3:4
Example 3
The preparation method of the starch/chitosan composite membrane is basically the same as that of the example 1, except that the volume ratio of the starch gelatinised liquid to the chitosan solution in the S1 is 5:5.
Example 4
The preparation method of the starch/chitosan composite membrane is basically the same as that of the example 1, except that the volume ratio of the starch gelatinised liquid to the chitosan solution in the S1 is 4:2.
Comparative example 1
A preparation method of a starch/chitosan composite membrane comprises the following steps:
s1, weighing 4.0g of starch, dissolving in 100mL of distilled water, slowly heating to 90 ℃, stirring at a constant speed of 150r/min to gelatinize the starch to form a gelatinized material, adding 25% of glycerol and 5% of NaCl according to the volume ratio, and stirring uniformly to obtain a starch gelatinized liquid;
0.6g CTS was weighed and added to 20mL of 2% CH 3 Obtaining chitosan solution with mass fraction of 3% in COOH solution;
mixing the starch gelatinization liquid and the chitosan solution according to the volume ratio of 4:2 to obtain starch/chitosan gelatinization liquid;
s2, adding 5 drops of dibutyl phthalate (DBP) into the starch/chitosan gelatinized liquid obtained in the S1, stirring at 1200r/min for 2 hours at room temperature to uniformly disperse the dibutyl phthalate/chitosan gelatinized liquid, coating the obtained starch/CTS mixed liquid into a PTFE mold after vacuum defoamation at-0.1 MPa, putting the PTFE mold into a freezing chamber for freezing for 12 hours, taking out, freezing for 12 hours after complete thawing, naturally airing at room temperature after repeating for 3 times in parallel, drying in a vacuum drying oven at 45 ℃, and uncovering a film to obtain a starch/CTS composite film sample, wherein the thickness of the starch/CTS composite film sample is (0.06+/-0.01) mm and is named as 4-starch/2-CTS.
Comparative example 2
The preparation method of the starch/chitosan composite membrane is basically the same as that of comparative example 1, and the difference is that the volume ratio of the starch gelatination liquid to the chitosan solution in S1 is 4:3.
Comparative example 3
The preparation method of the starch/chitosan composite membrane is basically the same as that of comparative example 1, and the difference is that the volume ratio of the starch gelatination liquid to the chitosan solution in S1 is 3:4.
Comparative example 4
The preparation method of the starch/chitosan composite membrane is basically the same as that of comparative example 1, and the difference is that the volume ratio of the starch gelatination liquid to the chitosan solution in S1 is 5:5.
Comparative example 5
A method for preparing a starch film, comprising the steps of:
s1, weighing 4.0g of starch, dissolving in 100mL of distilled water, slowly heating to 90 ℃, stirring at a constant speed of 150r/min to gelatinize the starch to form a gelatinized material, adding 25% of glycerol and 5% of NaCl according to the volume ratio, and stirring uniformly to obtain a starch gelatinized liquid;
s2, adding 5 drops of dibutyl phthalate (DBP) into the starch pasting liquid obtained in the S1, stirring at room temperature for 2 hours at 1200r/min to enable the mixture to be dispersed uniformly, coating the obtained starch mixture into a PTFE mold after vacuum defoamation at-0.1 MPa, putting the PTFE mold into a freezing chamber for freezing for 12 hours, taking out, freezing for 12 hours after complete thawing, repeating the freezing for 3 times in parallel, naturally airing at room temperature, drying in a vacuum drying oven at 45 ℃, and uncovering the film to obtain a starch film sample with the thickness of (0.06+/-0.01) mm.
The composite films of example 1 and comparative examples 1 to 5 were produced into 50mm X200 mm strips by the test according to GB/T3923.1-2013, and the thickness of each film sample was measured by a thickness gauge. The absolute breaking strength (F) of the composite film was measured using a YG 026T-type electronic fabric tester. The tensile strength at break (P) and the elongation at break (ε) are calculated according to formula (1):
Figure BDA0004139276880000061
in the formula (1), the tensile strength at P-break is MPa;
a-film width, mm;
b-film thickness, mm.
Figure BDA0004139276880000071
In the formula (2): epsilon-elongation at break,%;
l-the length of the sample stretched at break, mm;
L 0 the length of the test specimen when unstretched is mm.
FIG. 1 is a graph showing the mechanical properties of comparative examples 1-5 starch/CTS composite films. As can be seen from FIG. 1, chitosan can exert an increasing effect on the tensile strength of the film when the chitosan solution is in a mass with the starch gelatinization liquidWhen the product ratio is 3:4 (the mass ratio of the pure solid parts of chitosan and starch is 1:1), the absolute tensile strength reaches 28.62MPa, the elongation at break reaches 2.8%, the maximum value is reached, and the improvement is about 2 times compared with a single starch film. The mechanical property of the composite film depends on the structure and crystal form of the film molecules, and after starch and chitosan are uniformly mixed in the gelatinization liquid, the long chain of the molecule generates sufficient physical crosslinking, and free amino (-NH) in the chitosan molecule 2 ) And hydroxyl (-OH) can form hydrogen bond with-OH on starch molecular chain, so that toughness of the composite film is improved. With further increase of chitosan content, the mechanical properties of the composite film tend to decrease, probably because excessive chitosan is agglomerated in the film forming process, preventing free movement of molecules, and thus reducing the toughness of the film.
As can be seen from Table 2, M-Nano-TiO with a mass fraction of 0.1% was added 2 After that, the tensile strength at break and the elongation at break of the composite films of examples 1 to 4 were both improved compared to those of comparative examples 1 to 4, because of the modified TiO 2 The particles can fill in gaps among molecules of the composite film, so that the compactness of the composite film is improved, and the integral mechanical property of the film is enhanced. To sum up, starch/CTS/M-Nano-TiO 2 The composite film has the best mechanical property.
TABLE 1M-Nano-TiO 2 Influence of the addition of (C) on the mechanical properties of the composite film
Figure BDA0004139276880000072
Figure BDA0004139276880000081
The films prepared in example 1 and comparative examples 1-5 were prepared into 50mm X50 mm strips and tested according to GB/T2410-2008, and different chitosan and M-Nano-TiO were detected at 475nm wavelength using an ultraviolet-visible spectrophotometer 2 Absorbance (a) of the composite film of the content, light transmittance (T) was calculated according to formula (3):
T＝10 -A (3)
in the formula (3), the transmittance of the T-composite film,%;
absorbance of a-composite film.
As shown in table 2, in comparative examples 1 to 5, as the chitosan content was increased, the chitosan content increased from 0% to 42.8%, the transmittance of the starch/CTS composite film showed an increasing trend, and the average transmittance of the composite film increased from 34.2% to 39.3%, because the transmittance of the single starch gelatinized liquid was poor, while the CTS solution had a higher transparency; when the proportion of the chitosan solution in the film forming liquid is increased, the light transmittance of the film is increased, whereas when the content of the starch solution in the film is increased, the transparency of the composite film is reduced. When 0.1% M-Nano-TiO is added 2 As in examples 1-4, the composite film had reduced transparency due to M-Nano-TiO 2 As a heterogeneous powder filler, there is a refractive index difference with the composite film matrix, and light rays reduce transmittance due to interference phenomenon. In addition, M-Nano-TiO 2 The addition of (2) reduces the plasticization rate of the starch and the non-plasticised agglomerated starch particles also block part of the visible light transmission.
TABLE 2 starch, CTS, M-Nano-TiO 2 Relation between the ratio of (C) and the light transmittance of the composite film
Figure BDA0004139276880000082
Figure BDA0004139276880000091
Drying the composite film samples prepared in the example 1, the comparative example 2 and the comparative example 5 until the quality is constant, placing the processed samples on a sample frame of an IRAfforescence-1 type infrared spectrometer at 4000-400 cm -1 And carrying out infrared scanning in the wave number range to obtain an infrared spectrum of the sample.
FIG. 2 is an infrared spectrum of 3400cm in the composite films of example 1, comparative example 2 and comparative example 5 according to the present invention -1 at-OH and-NH 2 Multiple telescopic vibration peaks formed, 1200cm -1 And 2850cm -1 At the positions of methyl (-CH) 3 ) The characteristic peaks of chitosan in the composite membrane are basically reflected by the bending vibration peak and the stretching vibration peak. In addition, CTS and M-Nano-TiO 2 The addition of (3) does not increase or decrease the absorption peak, which indicates that the compatibility of the miscibility of the components is good. The two composite films are arranged at 1200cm -1 And 3400cm -1 The absorption peak intensity at the site is reduced compared with that of the single starch film, probably due to-OH and amino (-NH) groups in the chitosan molecular chain 2 ) with-OH and M-Nano-TiO in starch molecular chain 2 the-OH in the water molecules adsorbed outside the molecules forms hydrogen bonds, resulting in weakening of the absorption peak intensity.
The composite film samples of example 1 and comparative example 2 were cut into 5mm×100mm strips, subjected to a metal spraying treatment, and observed for the surface microstructure and morphology using a SU3500 type scanning electron microscope. FIG. 3 is a microstructure view (SEM) of a composite film of example 1 and comparative example 2 of the present invention, and in FIG. 3, a is example 1 and b is comparative example 2. As shown in FIG. 3, starch/CTS and starch/CTS/M-Nano-TiO 2 The composite film has even, continuous and smooth surface and no obvious layering phenomenon, which indicates CTS and M-Nano-TiO 2 The starch-based water-soluble polymer has good miscibility with starch base materials. However, by comparison, it was found that starch/CTS/M-Nano-TiO 2 The surface of the composite film has a white punctiform structure, which is starch particles which are not completely plasticized and are agglomerated, which indicates M-Nano-TiO 2 The addition of (2) has the effect of reducing the plasticizing performance of the starch, so M-Nano-TiO 2 The amount of (b) added should not be excessive, otherwise the mechanical properties of the composite film would be impaired.
The samples of example 1, comparative example 2 and comparative example 5 were cut to 20mm×20mm, placed in a D8 advanced diffractometer test chamber, and subjected to analysis of interactions between film-forming components by measuring conditions of a copper target, setting a tube current of 50mA, a voltage of 40kV, a scanning speed of 8 (°/min, and a diffraction angle range of 10 ° < 2θ < 80 °. FIG. 4 shows XRD patterns of composite films of example 1, comparative example 2 and comparative example 5 according to the present invention, and it can be seen from FIG. 4 that the three films have substantially the same trend, obvious peak patterns, and diffraction peaks of starch crystals all appear at 2θ=20°, indicating strong interactions between components in the composite filmsThe crystallinity is good. The diffraction peak area of the two composite films at 2 theta = 20 degrees is increased, the intensity is weakened, the crystallinity of the characterization starch base material is reduced, the addition of other two components is proved to change the crystal structure of the starch to a certain extent, the crystallization performance is weakened, and the two composite films are possible to be CTS and M-Nano-TiO 2 The strong action with-OH on the starch chain results in a crystal modification which is an important reason for the improved mechanical properties of the films.
The composite films prepared in example 1 and comparative example 2 were subjected to antibacterial property test
Agar, sodium chloride, peptone and beef extract were dissolved in 250mL of distilled water according to the formulation of table 3, and the pH was adjusted to 7.2 with sodium hydroxide solution to prepare a solid medium.
Table 3 media formulation
Raw materials Dosage (g)
Beef extract 1.25
Peptone 2.50
Sodium chloride 1.25
Agar-agar 5.00
The preparation of the liquid culture medium is also carried out in the same way, and after the preparation is finished, the liquid culture medium is respectively arranged on the culture mediumInoculating Escherichia coli and Staphylococcus aureus (Staphylococcus), and culturing at 37deg.C for 12 hr to make the strain enter into stable logarithmic phase to obtain bacterial liquid of Escherichia coli and Staphylococcus aureus. The solid culture medium is cooled to 60 ℃ after high-temperature steam sterilization, 0.4mL of escherichia coli and staphylococcus aureus bacterial liquid is respectively and evenly smeared on the surface of each solid culture medium, the bacterial liquid is evenly spotted on the center of a membrane by an inoculating loop, the solid culture medium in each culture dish is equally divided into 2 parts, and a composite film of comparative example 2 starch/CTS, starch/CTS/M-Nano-TiO of example 1 is prepared by using tweezers 2 One piece of composite membrane sample (20 mm multiplied by 20 mm) is stuck to each part, and bacteriostasis tests of two composite membranes are respectively carried out, and the same sample is tested for 3 times on each culture medium in parallel. E.coli is cultured for 1d at 37 ℃ under the inverted state, staphylococcus aureus is cultured for 5 hours under the same condition, the growth condition of each strain is observed, and the diameter of a bacteriostasis ring is measured. Comparing the colony diameter (D) with a blank control plate, evaluating the antibacterial performance of the two films by the diameter of the antibacterial ring, and calculating the antibacterial rate according to the formula (4):
Figure BDA0004139276880000111
in the formula (4), D is the diameter of a bacteriostasis ring of the tested sample, and mm;
d, diameter of a bacteriostasis ring of distilled water blank, and mm.
The diameter (D) of the inhibition zone is compared with the inhibition rate, and the inhibition effect of the two composite films on the growth of escherichia coli and staphylococcus aureus can be tested according to the fact that the antibacterial capacity is in direct proportion to the diameter of the inhibition zone. Fig. 5 shows the antibacterial properties of the present invention in example 1 and comparative example 2, and in fig. 5, a is example 1 and b is comparative example 2. The antibacterial test results of the composite film are shown in Table 4 and FIG. 5, and M-Nano-TiO is added to the 4-starch/3-CTS composite film 2 After that, the diameter of the bacteriostasis ring of the escherichia coli group is increased by 0.1mm, and the bacteriostasis rate is increased by 7.9%; the diameter of the inhibition zone of the staphylococcus aureus group is 0.7mm, and the inhibition rate is improved by 5.9%. M-Nano-TiO 2 The addition of the catalyst has better optimization effect on the antibacterial performance of the composite membrane, and the sterilization mechanism is T as a photocatalystiO 2 The electrons are excited under natural light condition, and electron holes with strong activity are left, which can be matched with TiO 2 Oxygen molecules adsorbed on the particle surface (O 2 ) Water molecules (H) 2 O) to generate hydroxyl radical (OH) and superoxide radical (O) 2- ) The two free radicals can decompose bacterial protein variation and sugar and esters, thereby killing bacteria. M-Nano-TiO with broad-spectrum antibacterial effect 2 The introduction of the composite membrane can effectively improve the antibacterial property of the composite membrane, thereby widening the application of the starch-based composite membrane material.
Table 4 antibacterial test results of composite film
Figure BDA0004139276880000121
It should be noted that, when numerical ranges are referred to in the present invention, it should be understood that two endpoints of each numerical range and any numerical value between the two endpoints are optional, and because the adopted step method is the same as the embodiment, in order to prevent redundancy, the present invention describes a preferred embodiment. While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (10)

1. The preparation method of the starch/chitosan composite membrane is characterized by comprising the following steps of:
s1, dissolving starch in water to form a gelatinized compound, and then adding glycerol and NaCl and stirring to obtain a starch gelatinized liquid; dissolving chitosan in acetic acid solution to obtain chitosan solution; mixing the starch gelatinization liquid and the chitosan solution to obtain starch/chitosan gelatinization liquid;
s2, dispersing nano titanium dioxide and a surfactant in water, ultrasonically obtaining nano titanium dioxide suspension, adding an ethanol solution into the suspension, adjusting the pH value to 9, performing ultrasonic dispersion, then performing water bath stirring reaction, adding a silane coupling agent solution, performing constant-temperature stirring reaction, centrifuging, filtering and drying to obtain modified nano titanium dioxide;
and S3, adding the modified nano titanium dioxide into the starch/chitosan gelatinization liquid, stirring for reaction, performing vacuum degassing, pouring into a mould, repeatedly freezing and thawing for 3 times, and drying to obtain the starch/chitosan composite membrane.
2. The method for preparing a starch/chitosan composite film according to claim 1, wherein in S1, the mass ratio of starch to water is 1-2:25-30, the gelatinization temperature is 90 ℃, the addition amount of glycerol is 25-27% of the volume of the gelatinized material, and the addition amount of NaCl is 4-6% of the volume of the gelatinized material.
3. The method for preparing the starch/chitosan composite film according to claim 1, wherein in S1, the mass-volume ratio of the chitosan to the acetic acid solution is 0.2-0.4 g:7-12 mL, and the volume fraction of the acetic acid solution is 2%.
4. The method for preparing a starch/chitosan composite film according to claim 1, wherein in S1, the volume ratio of the starch pasting liquid to the chitosan solution is 3-5:2-5.
5. The method for preparing a starch/chitosan composite film according to claim 1, wherein in S2, the mass ratio of the nano titanium dioxide to the surfactant to the water is 1.5-2:0.3-0.5:90-100, and the surfactant is one of sodium dodecyl benzene sulfonate, tween 20 or span 80.
6. The preparation method of the starch/chitosan composite film according to claim 1, wherein in S2, the volume ratio of the suspension to the ethanol solution is 2-4:1-3, the ethanol solution is prepared by ethanol and water according to the volume ratio of 1:1, the pH is adjusted by adopting ammonia water, the temperature of the water bath stirring reaction is 80-85 ℃, and the time is 20-25 min;
the volume ratio of the silane coupling agent solution to the suspension is 10:1, and the silane coupling agent solution is prepared from a silane coupling agent KH550 and water according to the mass volume ratio of 0.3g to 10 mL.
7. The method for preparing a starch/chitosan composite film according to claim 1, wherein in S3, the addition amount of the modified nano titanium dioxide is 0.1% of the mass of the starch/chitosan gelatinized liquid, and the stirring reaction time is 2 hours.
8. The method for preparing a starch/chitosan composite film according to claim 1, wherein in S3, the repeated freezing and thawing is performed after freezing at-18 ℃ for 12 hours.
9. A starch/chitosan composite film prepared by the method of any one of claims 1-8.
10. Use of the starch/chitosan composite film according to claim 9 for the preparation of an antibacterial product.
CN202310284552.9A 2023-03-22 2023-03-22 Starch/chitosan composite membrane and preparation method and application thereof Pending CN116178764A (en)

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