細(xì)菌纖維素表面修飾及功能化
發(fā)布時間：2018-08-12 19:43
【摘要】：細(xì)菌纖維素(BC)是國際公認(rèn)的一種優(yōu)異的天然納米生物材料,具有獨特的精細(xì)三維網(wǎng)狀結(jié)構(gòu),因其“納米效應(yīng)”而具有高比表面積、高吸水性及保水性、高氣液透過率、高濕態(tài)強(qiáng)度等優(yōu)異特性。目前BC膜材料已經(jīng)實現(xiàn)規(guī)�；a(chǎn),主要應(yīng)用于食品及醫(yī)用領(lǐng)域,解決了靜電紡納米纖維產(chǎn)量低,難以工業(yè)化生產(chǎn)的難題,具有十分廣泛的應(yīng)用前景。但目前BC材料的研究主要集中在生物發(fā)酵優(yōu)化以及低成本化方向,對于具有差異化結(jié)構(gòu)性能的BC改性材料及其相關(guān)功能納米材料的研究較少,而已報道的國內(nèi)外關(guān)于BC功能材料的研究主要集中于增強(qiáng)及醫(yī)用領(lǐng)域,其應(yīng)用領(lǐng)域也有待進(jìn)一步拓展。在BC衍生化及功能化過程中,其表面特性決定了BC的表面修飾方法選取與功能化復(fù)合體系的建立。而目前BC的性能研究大多集中在基礎(chǔ)理化特性的表征,而對其表面特性的研究報道較少。 因此,本篇論文通過系統(tǒng)化研究BC表面特性,包括BC表面可及羥基數(shù)量,不同羥基的可及性及氫鍵有序程度,BC纖維表面電動力學(xué)行為等,從而更好地指導(dǎo)差異化BC改性材料及BC基功能化材料的設(shè)計及制備,理解BC納米纖維在其中的模板作用以及納米反應(yīng)器效應(yīng)。 根據(jù)性能及應(yīng)用需求,探索BC改性材料的結(jié)構(gòu)設(shè)計和制備技術(shù),通過對BC納米材料進(jìn)行表面修飾,實現(xiàn)BC表面活性基團(tuán)的可控設(shè)計；并進(jìn)一步基于BC及其衍生化BC納米纖維活性位點控制的原位制備機(jī)理,采用不同方法原位可控構(gòu)筑新型BC基功能化納米復(fù)合材料體系,為提高BC附加值,拓展BC在光電信息等新材料領(lǐng)域應(yīng)用提供更為有效的方法和新的合成思路。 BC表面性能、表面修飾及功能化研究具體內(nèi)容如下： 1.研究了BC表面羥基可及度及其形態(tài)結(jié)構(gòu)與性能的關(guān)系,為BC表面修飾及功能化體系的拓展提供了理論依據(jù)。結(jié)果表明BC表面羥基可及數(shù)目為1.28(最大值為3),BC中O(2)H是三種羥基中最可及的,O(3)H最不可及,其與高度有序的O(3)H..O(5')分子內(nèi)氫鍵一致。BC的等電勢點pH為3.7,Splateau為-7.5mV。在中性及堿性條件下的BC模板效應(yīng)最顯著,其表面羥基基團(tuán)的大量解離可使其作為有效的反應(yīng)活性位點來控制納米顆粒及納米線材料的生長與分布。BC膜具有高比表面積(55.37m2/g),且其比表面積及其微觀形態(tài)可以通過不同的干燥方式及后處理進(jìn)行調(diào)控。 2.將BC優(yōu)異表面特性與實際應(yīng)用相結(jié)合,利用BC表面大量的可及性羥基基團(tuán)以及比表面積的可調(diào)控性,將BC膜材料固定在石英晶體微天平(QCM)表面,制備了一種新穎的具有高穩(wěn)定性和靈敏度的低成本濕度傳感器。結(jié)果表明傳感器展示了優(yōu)異的傳感特性,頻移對數(shù)對相對濕度顯示了線性關(guān)系,且基于BC膜的傳感器在97%相對濕度時靈敏度比相應(yīng)的纖維素膜增加了4倍多,所得傳感器具有優(yōu)異的可逆性及長期穩(wěn)定性。 3.通過采用乙�；百砂冯炕瘜W(xué)改性方法,以乙�；鶊F(tuán)及胺肟基團(tuán)部分取代BC納米纖維表面大量的羥基官能團(tuán),拓展BC在疏水增強(qiáng)基體材料及金屬離子吸附領(lǐng)域的應(yīng)用前景。使用碘作為催化劑,通過綠色高效無溶劑方法對BC納米纖維表面官能團(tuán)進(jìn)行乙�；男�,制備的乙�；疊C膜具有良好的表面疏水性能及優(yōu)異的機(jī)械性能(楊氏模量13.4GPa,拉伸強(qiáng)度225.8MPa),有利于作為疏水的非極性聚合物基體的增強(qiáng)材料。在保留BC聚集態(tài)結(jié)構(gòu)和一定物理機(jī)械性能的同時制備了偕胺肟改性BC,有效地提高了金屬離子的吸附容量,擴(kuò)展并豐富了BC納米纖維的模板效應(yīng)。 4.利用BC納米纖維表面大量的可及性羥基基團(tuán)與所引入組分的相互作用,可以通過簡單的表面修飾方法制備新穎的BC功能膜材料,有效拓展BC膜的應(yīng)用領(lǐng)域。通過在BC表面引入NO2SP組分成功制備了一種新型的BC-NO2SP光致變色納米纖維膜,該膜顏色可隨著BC-NO2SP膜結(jié)構(gòu)中吡喃組分的異構(gòu)化發(fā)生可逆變化；通過在BC表面引入聚乙烯亞胺(PEI)組分進(jìn)行表面修飾,成功制得了一種新穎、簡單且可重復(fù)使用的PEI-BC納米纖維膜基的QCM氣體傳感器,該傳感器在室溫下甲醛濃度1-100ppm范圍內(nèi)具有良好的線性,表現(xiàn)出高靈敏度,良好的可重復(fù)性和選擇性,開創(chuàng)BC納米纖維膜新的應(yīng)用領(lǐng)域。 5.利用BC及偕胺肟BC(Am-BC)的活性位點控制的原位合成機(jī)理以及納米反應(yīng)器效應(yīng),成功制備了具有光催化特性的ZnO/BC, ZnO/Am-BC及光致發(fā)光特性的CdSe/BC納米復(fù)合膜材料。結(jié)果表明所得復(fù)合膜結(jié)構(gòu)性能受反應(yīng)液濃度及反應(yīng)時間的影響,在優(yōu)化條件下,直徑為20-50nm的ZnO及CdSe納米粒子均勻分布在BC納米纖維的表面。Am-BC中胺肟基團(tuán)的引入為ZnO成核及生長提供了更多的有效活性位點,有效提高了ZnO納米顆粒負(fù)載量。相同條件下(120min),ZnO/BC/及ZnO/Am-BC復(fù)合膜對甲基橙溶液的光催化降解效率分別可達(dá)70%及91%,可應(yīng)用于有機(jī)污水處理,且易于回收,可循環(huán)利用。所得CdSe/BC柔性復(fù)合膜在紫外光激發(fā)下顯示出均勻的綠色熒光,可應(yīng)用于證券紙,傳感器及柔性熒光膜材料等領(lǐng)域。 6.采用BC作為模板材料,利用BC表面大量羥基與苯胺中的胺基相互作用,過硫酸銨作為氧化劑,通過原位氧化聚合苯胺制備了新穎的PANI/BC柔性導(dǎo)電納米復(fù)合膜。研究了反應(yīng)時間,摻雜酸對納米復(fù)合膜性能的影響。優(yōu)化條件下,PANI顆粒均勻沉積在BC納米纖維表面,沿著BC模板形成連續(xù)的直徑為200nm的納米鞘結(jié)構(gòu),該復(fù)合膜電導(dǎo)率可達(dá)5.0×10-2S/m,并具有優(yōu)異的柔性及良好的機(jī)械性能(楊氏模量5.6GPa,拉伸強(qiáng)度95.7MPa),且對應(yīng)力具有敏感性。該材料可應(yīng)用在傳感器,柔性電極,柔性顯示材料及其它柔性導(dǎo)電膜等領(lǐng)域,同時本工作也為BC應(yīng)用領(lǐng)域的拓展提供了新的方向。
[Abstract]:Bacterial cellulose (BC) is internationally recognized as an excellent natural nano-biomaterial with a unique fine three-dimensional network structure. Because of its "nano-effect", BC has many excellent properties, such as high specific surface area, high water absorption and water retention, high gas-liquid permeability, high wet strength and so on. In the field of food and medicine, it has solved the problem of low output of electrospun nanofibers, which is difficult to industrialize production, and has a very broad application prospect. However, at present, the research of BC materials mainly focuses on the optimization of bio-fermentation and low-cost direction. For BC modified materials with differentiated structure and properties and related functional nanomaterials. There are few studies on BC functional materials, but the research on BC functional materials at home and abroad mainly focuses on the field of reinforcement and medicine, and its application field needs to be further expanded. It is focused on the characterization of basic physical and chemical properties, but few reports have been reported on its surface characteristics.
Therefore, this paper systematically studies the surface properties of BC, including the number of accessible hydroxyl groups, the accessibility of different hydroxyl groups, the degree of hydrogen bonding order, and the surface electrodynamic behavior of BC fibers, so as to better guide the design and preparation of differentiated BC modified materials and BC-based functional materials, and to understand the template of BC nanofibers. And nano reactor effect.
According to the performance and application requirements, the structural design and preparation technology of BC modified materials were explored, and the controllable design of BC surface active groups was realized by modifying the surface of BC nano-materials; furthermore, based on the in-situ preparation mechanism controlled by the active sites of BC and its derivative BC nanofibers, novel BC in-situ controllable structures were constructed by different methods. The functionalized nanocomposites based on BCs provide more effective methods and new synthesis ideas for increasing the added value of BCs and expanding the application of BCs in the field of new materials such as optoelectronic information.
The details of surface properties, surface modification and functionalization of BC are as follows:
1. The relationship between the surface hydroxyl accessibility and the morphological structure and properties of BC was studied, which provided a theoretical basis for the surface modification of BC and the development of functional systems. The isoelectric potential of BC is 3.7 and Splateau is - 7.5 mV. In neutral and alkaline conditions, the template effect of BC is most significant. The dissociation of hydroxyl groups on the surface of BC can be used as an effective reactive site to control the growth and distribution of nanoparticles and nanowire materials. The area and its micro morphology can be regulated by different drying methods and post-processing.
2. A novel low-cost humidity sensor with high stability and sensitivity was fabricated by combining the excellent surface properties of BC with the practical application, using a large number of accessible hydroxyl groups on the surface of BC and the controllability of specific surface area. The sensitivity of the sensor based on BC membrane at 97% relative humidity is more than four times higher than that of the corresponding cellulose membrane. The sensor has excellent reversibility and long-term stability.
3. By using acetylation and amidoxime chemical modification methods, a large number of hydroxyl groups on the surface of BC nanofibers were partly substituted by acetyl group and amidoxime group, and the application prospects of BC in hydrophobic reinforced matrix materials and metal ion adsorption were expanded. The surface of BC nanofibers was modified by green and solvent-free method using iodine as catalyst. Acetylated BC films with good surface hydrophobic properties and excellent mechanical properties (Young's modulus 13.4GPa, tensile strength 225.8MPa) were prepared by acetylation modification of surface functional groups, which was beneficial to the reinforcement of hydrophobic non-polar polymer matrix. Oxime modified BC can effectively improve the adsorption capacity of metal ions, and expand and enrich the template effect of BC nanofibers.
4. Using the interaction between a large number of accessible hydroxyl groups on the surface of BC nanofibers and the components introduced, novel BC functional membranes can be prepared by simple surface modification methods, which can effectively expand the application fields of BC membranes. A novel, simple and reusable QCM gas sensor based on PEI-BC nanofiber membrane was successfully fabricated by introducing polyethylenimide (PEI) onto the surface of BC-NO2SP membrane to modify the color of the film reversibly with the isomerization of pyran components. With good linearity, high sensitivity, good repeatability and selectivity, BC nanofiber membranes have opened up new applications.
5. The photocatalytic properties of ZnO/BC, ZnO/Am-BC and CdSe/BC nanocomposite films were successfully prepared by the in-situ synthesis mechanism controlled by the active sites of BC and amidoxime BC (Am-BC) and the effect of nanoreactor. The results showed that the structure and properties of the films were affected by the concentration of the reaction solution and the reaction time. ZnO and CdSe nanoparticles with diameters of 20-50 nm were uniformly distributed on the surface of BC nanofibers under chemical conditions. Aminoxime groups in Am-BC provided more active sites for the nucleation and growth of ZnO and effectively increased the loading of ZnO nanoparticles. Under the same conditions (120 min), ZnO/BC/ZnO/Am-BC composite films photocatalyzed methyl orange solution. CdSe/BC flexible composite membrane exhibits uniform green fluorescence excited by ultraviolet light and can be used in securities paper, sensors and flexible fluorescent membrane materials.
6. A novel PANI/BC flexible conductive nanocomposite film was prepared by in-situ oxidation polymerization of aniline with ammonium persulfate as oxidant. The effects of reaction time and doping acid on the properties of the nanocomposite film were studied. The composite film has excellent flexibility and mechanical properties (Young's modulus 5.6 GPa, tensile strength 95.7 MPa) and is sensitive to stress. It can be used in sensors, flexible electrodes, and flexible. Display materials and other flexible conductive films, and this work also provides a new direction for the development of BC applications.
【學(xué)位授予單位】：東華大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：R318.08;TB383.1
本文編號：2180155
[Abstract]:Bacterial cellulose (BC) is internationally recognized as an excellent natural nano-biomaterial with a unique fine three-dimensional network structure. Because of its "nano-effect", BC has many excellent properties, such as high specific surface area, high water absorption and water retention, high gas-liquid permeability, high wet strength and so on. In the field of food and medicine, it has solved the problem of low output of electrospun nanofibers, which is difficult to industrialize production, and has a very broad application prospect. However, at present, the research of BC materials mainly focuses on the optimization of bio-fermentation and low-cost direction. For BC modified materials with differentiated structure and properties and related functional nanomaterials. There are few studies on BC functional materials, but the research on BC functional materials at home and abroad mainly focuses on the field of reinforcement and medicine, and its application field needs to be further expanded. It is focused on the characterization of basic physical and chemical properties, but few reports have been reported on its surface characteristics.
Therefore, this paper systematically studies the surface properties of BC, including the number of accessible hydroxyl groups, the accessibility of different hydroxyl groups, the degree of hydrogen bonding order, and the surface electrodynamic behavior of BC fibers, so as to better guide the design and preparation of differentiated BC modified materials and BC-based functional materials, and to understand the template of BC nanofibers. And nano reactor effect.
According to the performance and application requirements, the structural design and preparation technology of BC modified materials were explored, and the controllable design of BC surface active groups was realized by modifying the surface of BC nano-materials; furthermore, based on the in-situ preparation mechanism controlled by the active sites of BC and its derivative BC nanofibers, novel BC in-situ controllable structures were constructed by different methods. The functionalized nanocomposites based on BCs provide more effective methods and new synthesis ideas for increasing the added value of BCs and expanding the application of BCs in the field of new materials such as optoelectronic information.
The details of surface properties, surface modification and functionalization of BC are as follows:
1. The relationship between the surface hydroxyl accessibility and the morphological structure and properties of BC was studied, which provided a theoretical basis for the surface modification of BC and the development of functional systems. The isoelectric potential of BC is 3.7 and Splateau is - 7.5 mV. In neutral and alkaline conditions, the template effect of BC is most significant. The dissociation of hydroxyl groups on the surface of BC can be used as an effective reactive site to control the growth and distribution of nanoparticles and nanowire materials. The area and its micro morphology can be regulated by different drying methods and post-processing.
2. A novel low-cost humidity sensor with high stability and sensitivity was fabricated by combining the excellent surface properties of BC with the practical application, using a large number of accessible hydroxyl groups on the surface of BC and the controllability of specific surface area. The sensitivity of the sensor based on BC membrane at 97% relative humidity is more than four times higher than that of the corresponding cellulose membrane. The sensor has excellent reversibility and long-term stability.
3. By using acetylation and amidoxime chemical modification methods, a large number of hydroxyl groups on the surface of BC nanofibers were partly substituted by acetyl group and amidoxime group, and the application prospects of BC in hydrophobic reinforced matrix materials and metal ion adsorption were expanded. The surface of BC nanofibers was modified by green and solvent-free method using iodine as catalyst. Acetylated BC films with good surface hydrophobic properties and excellent mechanical properties (Young's modulus 13.4GPa, tensile strength 225.8MPa) were prepared by acetylation modification of surface functional groups, which was beneficial to the reinforcement of hydrophobic non-polar polymer matrix. Oxime modified BC can effectively improve the adsorption capacity of metal ions, and expand and enrich the template effect of BC nanofibers.
4. Using the interaction between a large number of accessible hydroxyl groups on the surface of BC nanofibers and the components introduced, novel BC functional membranes can be prepared by simple surface modification methods, which can effectively expand the application fields of BC membranes. A novel, simple and reusable QCM gas sensor based on PEI-BC nanofiber membrane was successfully fabricated by introducing polyethylenimide (PEI) onto the surface of BC-NO2SP membrane to modify the color of the film reversibly with the isomerization of pyran components. With good linearity, high sensitivity, good repeatability and selectivity, BC nanofiber membranes have opened up new applications.
5. The photocatalytic properties of ZnO/BC, ZnO/Am-BC and CdSe/BC nanocomposite films were successfully prepared by the in-situ synthesis mechanism controlled by the active sites of BC and amidoxime BC (Am-BC) and the effect of nanoreactor. The results showed that the structure and properties of the films were affected by the concentration of the reaction solution and the reaction time. ZnO and CdSe nanoparticles with diameters of 20-50 nm were uniformly distributed on the surface of BC nanofibers under chemical conditions. Aminoxime groups in Am-BC provided more active sites for the nucleation and growth of ZnO and effectively increased the loading of ZnO nanoparticles. Under the same conditions (120 min), ZnO/BC/ZnO/Am-BC composite films photocatalyzed methyl orange solution. CdSe/BC flexible composite membrane exhibits uniform green fluorescence excited by ultraviolet light and can be used in securities paper, sensors and flexible fluorescent membrane materials.
6. A novel PANI/BC flexible conductive nanocomposite film was prepared by in-situ oxidation polymerization of aniline with ammonium persulfate as oxidant. The effects of reaction time and doping acid on the properties of the nanocomposite film were studied. The composite film has excellent flexibility and mechanical properties (Young's modulus 5.6 GPa, tensile strength 95.7 MPa) and is sensitive to stress. It can be used in sensors, flexible electrodes, and flexible. Display materials and other flexible conductive films, and this work also provides a new direction for the development of BC applications.
【學(xué)位授予單位】：東華大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：R318.08;TB383.1
【引證文獻(xiàn)】
相關(guān)碩士學(xué)位論文 前3條
1 劉暉;細(xì)菌纖維素基復(fù)合材料的制備及性能研究[D];南京林業(yè)大學(xué);2016年
2 邢雪宇;細(xì)菌纖維素/明膠復(fù)合多孔支架的制備及性能研究[D];東華大學(xué);2016年
3 王紫蓉;固態(tài)細(xì)菌纖維素的制備及結(jié)構(gòu)研究[D];華南理工大學(xué);2016年
，本文編號：2180155
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