【作者】 王鸿博；

【导师】 祝志峰； 魏取福；

【作者基本信息】 江南大学 ， 纺织工程， 2007， 博士

【摘要】 纳米银粒子由于具有量子尺寸效应、表面效应和宏观量子隧道效应等许多特有的性质,具有银质材料所不具备的光电特性、光催化能力、抗菌、电磁屏蔽及吸收和发射光谱等性能。将纳米银粒子构建成薄膜是由试验向应用转变的重要环节。本文运用低温磁控溅射沉积技术在非织造材料表面沉积功能性纳米银薄膜,实现纺织材料的表面功能化。一方面克服采用纳米颗粒材料作为填料的纳米微粒团聚问题,减少加工工艺流程和污染;另一方面可以降低加工成本并实施在线加工。重点探讨非织造材料表面银功能纳米结构的形成原理、制备技术及其性能,满足市场上对功能非织造材料的需求。因此,本课题既具有前瞻性又具有可行性,并具有重要的学术价值和商业应用前景;同时本课题的研究将为功能非织造材料的广泛应用提供理论依据和实验基础。论文以丙纶(PP)和聚乳酸(PLA)非织造布为基材,制备纳米银抗菌薄膜;以涤纶(PET)非织造布为基材,制备具有良好导电、电磁屏蔽及防紫外透射功能的纳米银功能薄膜。主要探讨溅射工艺参数以及氩气等离子预处理对各性能的影响。利用扫描电镜(SEM)、原子力显微镜(AFM)和X射线能谱分析仪(EDX)研究了纳米银薄膜的表面微观形貌及组成成分;利用X射线衍射分析(XRD)研究纳米银薄膜的微结构;以四探针测试仪测定银薄膜方块电阻值;根据ASTM D4935—99标准测试镀银非织造布的电磁屏蔽效能;采用振荡烧瓶法测试非织造基纳米银薄膜的抗菌性能。结果表明,溅射时间和氩等离子预处理是影响抗菌性能的两大关键因素,而溅射功率、溅射压强,气体流量对抗菌性能影响较小。对于PP及PLA非织造布,对大肠杆菌和金黄色葡萄球菌的抑菌率均达100%时的纳米银薄膜厚度分别为3nm和2nm;在相同工艺条件下,经氩等离子预处理的纳米银薄膜抗菌性能有明显的提高,对大肠杆菌和金黄色葡萄球菌的抑菌率均达100%时的纳米银薄膜厚度仅分别是2nm和0.5nm。溅射工艺参数影响薄膜的导电、电磁屏蔽和透射率。导电性能随着膜厚的增加而增强;对相同厚度的薄膜,随着溅射功率的增加,导电性能下降;随着氩气压强的增大,导电性能先下降后提高;电磁屏蔽效能(SE)随着薄膜厚度的增加而增大,膜厚为100nm时屏蔽效能(SE值)达到了26dB以上(屏蔽率大于99.7%);在250～600nm波长范围内,非织造基纳米银薄膜表现为极强的紫外和可见光屏蔽功能,薄膜厚度达到50nm以上,其透光率均在6%以下。论文首次提出非织造基纳米银薄膜的复合抗菌机理,即银离子的溶出抗菌和纳米银薄膜的表面抑制抗菌。一方面由于银离子的溶出及其活性作用,另一方面,基材通过氩等离子预处理及溅射银膜后,细菌对PP(或PLA)基溅射银膜表面的粘附自由能由负转为正,表明粘附过程难于发生,即使粘附也是可逆的,可从能量的角度较好的解释了溅射纳米银薄膜的表面抑制细菌性。论文探讨了金属与高分子基材之间的界面结合机理,分析基材预处理方式对界面结合牢度的影响,用耐磨法及剥离法较好的表征了薄膜与基材之间的结合牢度。首次提出在非织造基表面溅射纳米银薄膜具有分形特征的观点,分形维能较好的描述薄膜表面形貌;分形维越大,薄膜表面质量越高,分形维越小,表面质量越差。分形维与薄膜表面的导电性、颗粒直径、屏蔽性能均具有对应关系。论文研究了非织造基纳米银薄膜的生长机理及其微结构,对银薄膜厚度小于5nm的纳米银抗菌膜,可以认为是层生长型,因为溅射后薄膜的粗糙度未有明显的变化;对厚度在30-40nm以上的纳米银薄膜,主要是核生长模式或层加岛模式,这与基材表面状态、基材温度、溅射工艺条件有关。微结构分析表明:采用磁控溅射法在非织造布基材上沉积了不同厚度的Ag膜,Ag膜的晶体结构仍为面心立方,呈多晶状态,随着银膜厚度的增加,薄膜的平均晶粒尺寸逐渐变大。更多还原

【Abstract】 Silver nanoparticles possess the opto-electrical,photocatalitic,anti-bacterial and electromagnetic shielding properties,which common silver materials don’t have,due to quantum effect,surface effect and quantum tunneling effect.The construction of nanostructure silver films from silver nanoparticles is the key step in the applications of this material.In this research,low temperature magnetron sputter coating was employed to deposit nanostructured silver films on the surface of nonwovens to functionalize the textile materials.The use of magnetron sputter coating not only overcomed the problems of aggregation of nanoparticles as filling particles,but also shortened the production processes and eliminated the water pollution.The use of magnetron sputter coating,on the other hand,could reduce the processing cost.This research focused on the formation principle of the nanostructured silver,preparation techniques and properties of the nanostructured silver deposited on the surface of nonwovens to meet the demands of the markets for functional textiles.This work will provide the theoretical and practical guidance for the development of functional textiles based on its advanced and practical findings.The antibacterial silver films were deposited on polypropylene(PP) and PLA nonwovens and the silver films with the properties of conductive,electro-magnetic shielding and anti-ultraviolet radiation were deposited on polyester(PET) in this project.The effects of sputtering parameters and argon plasma pretreatment for nonwovens on the properties of the samples were investigated.The surface morphology was observed with scanning electron microscopy(SEM) and atomic force microscopy(AFM).Surface chemical compositions were examined employing X-ray energy dispensive spectrometer(EDX).The crystal structures of silver films were observed using X-ray diffraction(XRD).Electrical resistances of silver films were measured by four-probe tester.Electro-magnetic shielding properties of nonwovens coated with silver films were assessed according to ASTM D4935-99 test standard.The antibacterial performance was tested using shake flask test.The test results indicated that deposition time and argon plasma pretreatment were the two key factors affecting antibacterial properties of the coated materials, while sputtering power,gas pressure and gas flow had a slight influence on antibacterial properties.Both the reduction percentage of Staphylococcus aureus and Escherichia coli bacteria reached 100%for PP nonwovens,when the silver film thickness was above 3nm.Both the reduction percentage got to 100%for PLA nonwovens,as the coating thickness exceeded 2nm.Under the same processing conditions,the coated samples with argon plasma pretreatment showed the better antibacterial performance.The reduction percentage of both the bacteria tested reached 100%for the pretreated PP and PLA nonwovens,when the film thickness got to 2nm and 0.5nm respectively.Sputtering parameters also affected the electrical, electromagnetic and ultra-violet transmission properties of the coated materials.Electrical conductivity was improved as the film thickness increased.With the same film thickness,the electrical conductivity was decreased as the sputtering power increased,while the electrical conductivity was first decreased and then improved as the pressure of argon increased.Electromagnetic shielding effect(SE) was increased as the film thickness increased.As the film thickness got to 100nm,the value of SE was above 26dB(shielding effect was over 99.7%).The nanostructured silver films also exhibited great ultraviolet and visible light shielding effect.The transmittance is below 6%in the wavelength range between 250 and 600nm when the film thickness was above 50nm, Multiple antibacterial mechanism of nanostructured silver films deposited on nonwovens were first provided in this paper.The silver ions released from the nanostructured silver films and the active action of the released silver ions,on one hand,led to the antibacterial effect and the adhension free energy between bacteria and the coated silver films,on the other hand,converted from negative to positive after argon plasma pretreatment and silver sputter coating,indicating that act of adhension could hardly take place. The adhension was reversible even if it happened.Thus,the antibacterial mechanism was well explained from the viewpoint of energy.The mechanism of the interfacial adhension between silver and polymer substrate was examined and discussed.The effec of argon plasma pretreatment on interfacial adhension strength was analyzed,and the adhension strength between silver films and substrate was characterized by abrasion test and peel-off test. The fractal characteristic of the silver films sputtered on nonwovens was analyzed for the first time.Fractal dimensions could well describe the surface topography of the sputtered films on the nonwoven substrates. The larger fractal dimension indicated the better surface topography.Fractal dimension was closely related to the electrical conductivity,the grain size and the electromagnetic shielding properties of the sputtered films.The growth mechanism of nanostructured silver films and the microstructure of films were investigated and explained.The growth model could be considered as layer growth when the silver film was less than 5nm.This was because the roughness of the sputtered film did not show any significant change. The growth model was regarded as nucleus growth or island growth as the film thickness was between 30nm and 40nm.It was related to the surface state of the substrate,the temperature of the substrate and the sputtering conditions.The study revealed that the crystal structure of silver films with different thicknesses on nonwovens substrate was face centered cubic.The increased film thickness led to larger average grain size of the silver crystals.更多还原