【作者】 李国红；

【导师】 刘宏； 刘向阳；

【作者基本信息】 山东大学 ， 材料学， 2011， 博士

【摘要】 蚕丝是一种天然的蛋白质纤维,其丝质轻、光滑、柔软而富有弹性,且具有其他纤维无法比拟的美丽光泽,历史上有“纤维皇后”的美誉；且因其手感舒适、良好的吸湿透气性和对人体的保健作用,也享有“人体第二肌肤”的美誉。随着现代社会发展对环境保护意识的加强,人造纤维生产过程中对环境的污染问题引起社会的高度重视；加上人造纤维最重要原料之一-原油的缺乏,市场消费者越来越崇尚自然,追求舒适、保健、美观、绿色的纺织品。蚕丝从栽桑养蚕到成丝过程都没有污染,于是天然蚕丝产品越来越受到消费者的青睐。现全球每年大于1.2亿吨的产丝量,使它成为纺织业中极其重要的天然原材料。但与人造纤维相比,蚕丝制品易折皱,细菌滋生引起的性能下降,光致发黄、老化等内在的不足,在消费者追求衣料穿着舒适性和功能性兼顾的今天,已成为制约蚕丝制品市场竞争力的主要原因。在不损害蚕丝优良性能的前提下,将蚕丝与其它功能性纳米材料复合,是一种克服蚕丝本身性能缺陷、赋予蚕丝产品全新优良性能的有效方法。作为一种新型光催化剂、抗紫外线剂、光电材料等,TiO2以其神奇的功能,在空气净化、抗菌防霉防污、污水处理、太阳能电池、化妆品防晒等领域有广阔的应用。随着其产品工业化生产和功能性应用发展的日趋成熟,它在环境、信息、材料、能源、医疗与卫生等领域的技术革命中将起到不可低估的作用。TiO2@Ag纳米颗粒,即在TiO2表面沉积抗菌效果优异的贵金属银Ag纳米颗粒,不但很好地提高了TiO2的光催化活性,还解决了贵金属催化剂的颗粒粒径达到了纳米级别后存在的团聚、失活、和流失等问题,解决了贵金属Ag催化剂的应用过程中的关键问题。据查文献,目前还没有将TiO2和TiO2@Ag纳米颗粒与蚕丝通过化学键方法牢固结合的报道,也没有将纳米颗粒“植入”蚕丝内部的报道。本论文首次通过三种方法,将TiO2和TiO2@Ag纳米颗粒与蚕丝牢固结合,真正意义上将二者构建成一个完整的体系,从而赋予了蚕丝全新的、甚至永久性的优越性能,制备了多功能的蚕丝复合材料。本论文的主要工作内容如下：1、纳米颗粒的合成和表面改性通过光催化还原金属离子的方法将贵金属银纳米颗粒沉积到二氧化钛P25表面,制备了TiO2@Ag纳米颗粒。通过TEM、SEM、XPS等手段对样品进行表征,结果表明,贵金属银离子都被还原形成单质银纳米颗粒,并且在Ti02纳米颗粒周围分散良好,颗粒均匀一致,约为5nm。利用这种方法制备TiO2@Ag纳米材料,制备工艺简单,表面洁净无污染,不需要添加任何表面活性剂。用3-(3,4-二羟基苯基)丙酸(DHBPA)对Ti02和TiO2@Ag纳米颗粒进行表面改性,Ti原子表面原本吸附的羟基-OH,被DHBPA结构中的两个羟基-OH取代,形成二羟基配位结合的双齿结构。即利用烯二醇配体与金属氧化物结合的原理,使DHBPA吸附在纳米颗粒表面,实现对Ti02和TiO2@Ag纳米颗粒的表面改性。2、纳米颗粒-壳聚糖功能化蚕丝以1,2,3,4-丁烷四羧酸作为连接剂,用壳聚糖对蚕丝进行预处理,在蚕丝上引入壳聚糖的大量-NH2基团。吸附在纳米颗粒表面3-(3,4-二羟基苯基)丙酸(DHBPA)中的羧基-COOH,与预处理过蚕丝表面的大量氨基-NH2基团通过离子键结合,Ti02和TiO2@Ag纳米颗粒分别通过化学键牢固的结合在蚕丝表面,即使经过剧烈的超声清洗,纳米颗粒仍然牢固、均匀的结合在蚕丝表面,表明蚕丝和纳米颗粒形成一个完整、牢固的体系,制得Ti02和TiO2@Ag改性的蚕丝制品。由于Ti02和TiO2@Ag的防护作用,功能化后的蚕丝有出较高的紫外防护能力,对革兰氏阴性菌大肠杆菌和革兰氏阳性菌金黄色葡萄球菌有良好的抗菌和抑菌能力。并且在紫外光照下,6小时候就能够把在废水中具有一定代表性的甲基橙降解90%以上,证明Ti02和TiO2@Ag功能化的蚕丝具有较强光催化自清洁的能力。本方法采用纺织工业中传统的整理工艺,并且采用自然界的天然产物-壳聚糖和质优价廉的Ti02为原材料,制备出低成本高性能的功能蚕丝制口。3、纳米颗粒-2D树脂功能化蚕丝2D树脂我国目前应用广泛的织物整理剂,纺织工业中2D树脂整理技术是天然纤维中最具成效的代表性工艺,工艺成熟,效果优良。本实验中采用2D树脂整理工艺对蚕丝进行预处理。吸附在Ti02和TiO2@Ag纳米颗粒表面3-(3,4-二羟基苯基)丙酸(DHBPA)中的羧基-COOH,与预处理过蚕丝表面2D树脂的大量羟基-OH基团发生缩合反应,使纳米颗粒牢固地结合在蚕丝表面,可以经得起剧烈的超声清洗。经过Ti02和TiO2@Ag纳米颗粒功能化后,蚕丝被赋予了出色的紫外防护能力、抑菌能力和光催化自清洁能力。在赋予蚕丝全新功能的同时,还提高了蚕丝抗折皱能力和定型能力。4：将Ti02纳米颗粒“植入”蚕丝内部。蚕丝的丝素蛋白纤维并不是完全实心的纤维,而是由许多直径-1um的细丝纤维并列在一起构成,细丝纤维之间存在微孔隙。细丝纤维又是由直径约为10nm的微纤维并列组成,微纤维之间也存在微孔隙。从而使得蚕丝纤维的空隙率达38%左右,这就为将Ti02纳米颗粒“植入”蚕丝内部提供了可能。实验中,将蚕丝浸泡于钛的液态前驱体-钛酸四丁酯(TBOT)中,溶剂分子不但物理吸附在纤维表面,也向纤维内部微小的空隙渗透。接下来在中性、温和的水热条件下水解醇钛盐,不但在蚕丝纤维表面制得理想晶型晶貌的锐钛矿相Ti02纳米颗粒,还首次将Ti02纳米颗粒植入在蚕丝纤维内部,二者真正合二为一形成一个体系,把锐钛矿Ti02纳米材料的优良特性永久性赋予蚕丝。Ti02功能化后的蚕丝克服了其原本光致发黄、老化的缺陷,表现了出色的防老化能力,且由疏水性改为超亲水性。蚕丝材料对水的吸收能力和透气性的提高,将会提高穿着舒适性和透气性。采用光催化还原的方法,将贵金属银纳米颗粒沉积到Ti02改性后的蚕丝上,制得由TiO2@Ag纳米颗粒功能化的蚕丝,赋予了蚕丝优秀的紫外线防护性能、抗菌能力和光催化自清洁能力。本实验技术采用的低温水热合成法和光催化还原法制备Ti02和TiO2@Ag纳米颗粒功能化的蚕丝,整个实验制备过程不需高温烧结即可直接得到晶型晶貌理想的锐钛矿TiO2纳米颗粒,避免了高温对蚕丝的严重伤害。并且不添加任何表面活性剂或者是模板来控制颗粒的尺寸和形状,该制备工艺简单,所得蚕丝制品表面洁净无任何污染。综上所述,本研究首次通过化学键连接,实现了蚕丝与TiO2和TiO2@Ag纳米颗粒的牢固结合；首次将锐钛矿TiO2纳米颗粒“植入”蚕丝内部,使二者真正合为一个体系。纳米颗粒功能化的蚕丝被赋予了长久性的紫外防护、抗菌、自清洁等性能,制得多功能的蚕丝复合材料。更多还原

【Abstract】 Silkworm Silk, known as "queen of textile" in the history, is a natural protein fiber. Silk has light, smooth, soft texture, and the beautiful luster that other fibers can not be reach. For its comfortable hand-feel, moisture permeability and health care effect to human body, silk also has the reputation as "second skin of body".With the development of awareness of enhancement on the environment protection of modern society, the environment pollution in the production process of synthetic fibers has aroused great attention. Furthermore, as the crude oil, one of the most important raw materials of synthetic fibres, is running out in years to come, industry and consumer market prefer multifunctional natural, comfortable and healthy textile product to synthetic fibers. From mulberry planting and silkworm culture to filamentation, silk is not contaminated, that enables its increasing interest from consumers. Furthermore, more than 1.2 M tons of silkworm silks are produced around the world annually and the high production makes it a vital raw material in the textiles market.However, compared to other synthetic fabrics, silk fibroin fabric (SFF) still has its inherent disadvantages, such as wrinkle, deformation and even degradation caused by Microorganism, photo-induced aging and yellowish, that has been the main restrictions of market competitive activity. Without damaging the excellent properties of silk, combining silk with functional nano materials is an effective way to overcome its shortcomings and endow it completely new properties.Nano-scale TiO2, as a novel photocatalyst, and an anti-UV and photoelectric effect agent, has broad application in air purification, antibacterial, mold prevention, anti-fouling, sewage treatment, sunscreen lotion and other fields. With the industrialized production and maturation of application developing, nano-TiO2 plays a hardly underestimated role in the environment, information, materials, energy, medical and health fields. TiO2@Ag nano composite materials, not only effectively improve the photo-catalytic activity of TiO2, but also solve the key problems of noble metal Ag catalyst in the application process, such as aggregation, inactivation, loss, etc.According to references investigation, there is no report on combination of silk and nano-TiO2 through chemical bonds, or "implanting" nanoparticles (NPs) inside the bulk of silk.In order to build a complete system for combining silk and functional NPs (TiO2 and TiO2@Ag) strongly, for the first time, three methods are developed, endowing silk completely new and permanent superior performance to produce multi-functional silk composite materials.The main works are as follows:1、Synthesis of TiO2@Ag NPs and surface modification of NPsTiO2@Ag hetero-structured nano composite material was prepared by photocatalytic reduction method. The prepared TiO2@Ag was characterized by TEM, SEM, XPS, etc. The results show that the silvers ions were reduced to elemental Ag NPs. Ag NPs, with the grain size of about 5nm, deposited on the surface of TiO2 NPs with well dispersivity. The preparation process is simple, without template and surfactant as additives. So the as-made product has clean and pollution-free surface.3-(3,4-dihydroxyphenyl) propionic acid (DHBPA) was used to modify the surface of TiO2 and TiO2@Ag Nps. The hydroxyl groups -OH on TiO2 and TiO2@Ag NPs surface are replaced by the two bidentate OH groups of DHBPA. DHBPA is adsorbed on the NPs surface and modifies the surface of TiO2 and TiO2@Ag NPs.2. TiO2 and TiO2@Ag Nanoparticles-Chitosan functionalized silk Silk is pre-modified with chitosan, using 1,2,3,4- Butanetetracarboxylic acid as crosslinker. The carboxyl group -COOH of DHBPA that attached to TiO2 and TiO2@Ag NPs surface reacted with the amino groups of chitosan by ionic bonding. Owing to the strong chemical bonds, TiO2 and TiO2@Ag NPs strongly attched onto the silk surface, even after ultrasonic washing process. Owing to the protection effects of NPs, the NPs functionalized silk have excelent UV protection ability, and anti-bacterial ability against gram-negative bacteria E. coli and gram-positive bacteria S. aureus. Under ultraviolet irradiation test, the functionalized silk were able to degrade more than 90% methyl orange, proving that the silk functionalized by TiO2 and TiO2@Ag NPs have photocatalytic and self-cleaning abilities.This method adopt the traditional finishing process in textile industry and use natural products-chitosan and TiO2 as raw materials, producing high-quality and multi-functional silk products with low cost.3、TiO2 and TiO2@Ag Nanoparticles-2D resin functionalized silk2D resin is widely used in textile industry as a finishing agent.2D resin finishing technology is the mature, effective and a representative technology for natural fibers finishing. The silk was pre-modified by 2D resin finishing technology. The carboxyl group -COOH of DHBPA that attached to the NPs surface reacted with the hydroxyl groups of 2D resin through condensation reaction, and the Nps strongly linked to the silk surface, even after ultrasonic washing process. After functionalization, silk gains excellent UV protection ability, anti-bacterial ability, photo-catalytic and self-cleaning ability. At the same time, the functionalized silk overcomes its easy-wrinkle defect.4. "Implanting" TiO2 nanoparticles inside the bulk of silk fibers.Silk fibroin fiber is not completely solid, but is constituted by numbers of filaments about 1um in diameter with micropores between them. At the same time, a filament is constituted by～10nm fibrils with micropores between them. The constructional features of silk contribute to its 38% porosity, making it poddible to "implant" NPs inside the bulk of silk. So when we soak the silk in the liquid itanium precursor-tetrabutyl titanate (TBOT), the solvent molecules not only adsorbed onto the fibers surface, but also penetrated into the bulk of silk fibers. The following neutral hydrothermal process hydrolyzed TBOT and promoted anatase TiO2 NPs formation not only on the fibers’surface, but also inside the bulk of silk fibers. Silk and TiO2 NPs formed a complete system. TiO2 functionalized silk overcomes its light-induce yellowing and aging defects, and gains excellent anti-aging ability. At the same time, silk changes from hydrophobic to super-hydrophilic. The enhancement of water absorption capacity and permeability will improve the comfortability of wearing.Through photocatalytic reduction method, silver nanoparticles deposited on the TiO2 functionalized silk and then TiO2@Ag functionalized silk were prepared. TiO2@Ag functionalized silk are endowed with excellent UV blocking, antibacterial and self-cleaning ability.We adopt low temperature hydrothermal method and photo-catalytic reduction method, without sintering process which destroys silk, or adding any surfactants or templaes to control the particles size and shape. So the NPs functionalized silk have clean surface without any pollution.In summary, for the first time, the study realized the tightly chemical bonding between silk and TiO2 and TiO2 @ Ag nanoparticles; for the first time, TiO2 NPs are "implanted" inside the bulk of silk fibers, forming a whole system. The TiO2 and TiO2@ Ag NPs functionalized silk are endowed with permanent UV proection, anti-bacterial, self-cleaning abilities, producing high-quality and multi-functional silk composite materials.更多还原