棉纤维素蒸汽闪爆改性及其羧甲基化研究

研究了采用高压蒸气闪爆技术对原棉纤维进行预处理，以改性后的纤维为原料合成羧甲基纤维素，并优化了合成工艺。以产品的取代度为指标，研究了高压蒸气闪爆处理条件对产品性能的影响。结果表明，随着闪爆压力的提高，产品的性能有不同程度的提高。     

由分子链构象转变及结构重组引起的聚3,4-乙烯二氧噻吩-聚苯乙烯磺酸/聚乙烯醇纤维高性能化

采用一种新颖的二甲基亚砜(DMSO)蒸汽处理的方法制备高导电性的(聚3,4-乙烯二氧噻吩-聚苯乙烯磺酸盐/聚乙烯醇)(PEDOT:PSS/PVA)有机导电纤维.通过分析蒸汽处理前后纤维在化学结构、形貌、表面化学组分及分子链构象等方面的变化,探究蒸汽处理提高纤维导电性能的机理.结果表明,蒸汽处理引起纤维内部结构重组和分子链构象转变,显著提高了纤维导电性能.蒸汽处理使PEDOT和PSS间发生相分离,部分无定形的PSS链段富集到纤维表面,减少了毗邻的导电PEDOT颗粒间绝缘的PSS层厚度,促使导电PEDOT颗粒之间形成更好的导电网络通路,进而增强纤维导电性能.蒸汽热处理还使PEDOT分子链构象由苯式结构转变为利于载流子传输的醌式结构.随着蒸汽处理的进行,纤维表面变得光滑,表面粗糙度下降;同时,纤维的力学性能有所提升.     

蚕丝改性方法概述

天然的蚕丝具有独特的优良性能,但同时也存在性能缺陷,如力学性能（拉伸强度与韧性）差,使用时间短以及色牢度差等。科学家们发展了蚕丝的改性技术,改良蚕丝的性能以达到更好的应用目的。目前常用的蚕丝改性方法主要分为基因改性方法、物理改性法、化学改性法及添食育蚕法等。概述了蚕丝的结构与改性的原理,介绍了4类改性法及其近年来取得的重要进展,总结了目前蚕丝改性研究中的难点,展望了蚕丝改性研究的未来发展方向。     

仿丝素纤维的研究进展

简要回顾了外观和形态仿蚕丝发展技术,重点分析了结构仿蚕丝丝素的国内外研究现状,探讨了结构与功能仿丝素纤维的途径、方法和存在的困难,包括丝素再生、聚氨基酸合成、聚氨基酸与非肽片段共聚物合成、基因工程法仿丝素蛋白质的合成及其纤维化等.基于天然大分子蚕丝丝素与合成高聚物聚氨酯同时具有类似的酰胺链结构和微相分离的聚集态结构,提出了以含有丝素特征寡肽片段的特殊聚氨酯仿丝素纤维的可行性构想,以期有助于蚕丝合纤化.     

蚕丝基智能纤维及织物：潜力、现状与未来展望

纤维及织物因具有良好的柔性、透气性以及适宜的力学性能而成为人们日常生活必不可少的材料。随着柔性电子器件的快速发展,纤维及织物在其自身优势的基础上,开始被人们赋予智能化特征,使得智能纤维和织物逐渐在可穿戴领域占据一席之地。天然蚕丝具有产量大、机械性能优异和生物可降解的优势。近年来,面向智能应用的蚕丝基纤维与织物逐渐发展,被用于传感、致动、光学器件、能量收集和储能等领域。本文将首先介绍天然蚕丝的层级结构和性能,并介绍各种形貌结构的再生蚕丝材料;然后根据其在智能纤维及织物中应用领域的不同,详细阐述蚕丝基智能纤维及织物的制备方法、性能及工作机制;最后讨论进一步发展所面临的挑战与机会,并对未来前景进行展望。     

蚕丝蛋白的结构和功能

较为全面地综述了最近几十年国内外关于蚕丝蛋白的组成，结构，性能及其应用的研究和作者课题组十几年在蚕丝蛋白方面的工作。     

多孔碳材料的化学气相后处理及其超级电容性能

以廉价的椰壳为原料制备了高比表面积的多孔碳材料,然后在密闭的反应釜中以硝酸蒸汽对多孔碳材料进行了后处理,制备了亲水性更好的多孔碳材料。采用扫描透射电子显微镜(TEM)、物理吸附、X射线粉末衍射(XRD)、拉曼光谱(Raman)和接触角测试对材料的微观形貌、孔道结构、组成和亲水性进行了表征,探究了不同温度下硝酸蒸汽对多孔碳材料的形貌、结构的影响,并采用循环伏安法、恒电流充放电法和交流阻抗法考察了多孔碳材料的超级电容性能。结果表明,经过硝酸蒸汽处理后的多孔碳材料的比表面积和孔体积均有所降低,且随着处理温度的升高,降低得更加明显,而亲水性却越来越好。电化学测试结果表明,经过100℃硝酸蒸汽处理的多孔碳材料(CSC-100)具有最佳的超级电容性能。在以6 mol·L^-1 KOH为电解液的三电极体系中,当电流密度为0.5 A·g^-1时CSC-100的比电容可达452.9 F·g^-1,而未经硝酸蒸汽处理的多孔碳材料(CSC)的比电容仅为350.4 F·g^-1。电容贡献分析表明CSC-100良好的亲水性和表面官能团不仅提高了双电层电容,也提高了赝电容。     

蚕丝丝素纤维中氨基酸在丝素纤维的径向分布研究

通过显微镜观察、红外光谱、氨基酸组成分析、福林试剂分析等方法研究蚕丝丝素纤维的微结构、丝素表层和内层的结构差异 ,研究氨基酸尤其是对丝素纤维的结构和性能起重要影响的主要芳香族氨基酸———酪氨酸在丝素由表及里各层中的含量和分布 ,以期最终揭示丝素结构与蚕丝织物应用中的固有缺陷 (如泛黄、易皱、色牢度等 )的关系 .结果表明蚕丝丝素存在多层次结构 ,表层无定形区的比例较高 ,里层结晶区的比例较高 ;侧基较大的氨基酸和赖氨酸、组氨酸、胱氨酸、精氨酸、天门冬氨酸、苯丙氨酸、亮氨酸、谷氨酸、酪氨酸等在丝素的表层分布相对较多 ,而乙氨酸、丙氨酸、丝氨酸等小侧基氨基酸则在中间层至里层较多     

桑蚕丝素蛋白的结构、形态及其化学改性

通过对桑蚕吐丝机构的描述,着重从高分子科学的角度介绍桑蚕丝和蚕丝素蛋白大分子的组成、形态及各种化学、物理性质,讨论了蚕丝素蛋白的纤维化机理,并简述了丝索蛋白纤维的化学接枝改性及其应用。     

超临界二氧化碳处理对聚酯纤维结构及其性能的影响

用DSC、扫描电镜、X射线衍射、萨那蒙法对超临界二氧化碳处理聚酯纤维的熔点、表面形态结构、聚集态结构进行测定,并对处理后织物的收缩性能进行了分析探讨。实验结果表明：随着超临界二氧化碳处理温度、压力的提高,聚酯纤维的熔点、熔融热略有增加,纤维表面的低聚物增多,纤维的结晶度增加,取向度略有下降,同时聚酯织物的收缩率增加。预定型处理有助于提高聚酯纤维的热稳定性,降低二氧化碳处理对聚酯织物收缩率的影响。     

Oriented nucleation of hydroxylapatite crystals on spider dragline silks

Spider dragline silk as a protein fiber can be pictured as the oriented organization of protein nanocrystals along the long axis with their spacing filled by amorphous protein domains. We used the surface of the spider dragline silk as a biological template to nucleate bone mineral hydroxylapatite (HAP) site-specifically from a HAP-supersaturated solution. HAP crystals were found to be nucleated on the surface of silks with their c axis preferentially oriented at an average angle of 72.9 degrees with respect to the long axis of the silks. The preferred orientation is nearly identical among the different mineralized silks that we studied. Other materials such as Au and CdS could be nucleated on the silks but did not show any preferred orientation. We believe that the oriented nucleation of HAP is directly related to the structures of silks and HAP. The mineralized silks will combine the good mechanical properties of the spider silks and the biocompatibility of HAP and may be assembled into ideal biomaterials as bone implants.     

基于动物丝蛋白的人工纺丝

动物丝,特别是蜘蛛丝近年来由于其优异的综合力学性能而备受关注。但是天然动物丝的应用由于种种原因而受到各种限制,因此人们期望通过人工纺丝获得性能与天然动物丝相近的人工丝纤维。本文就采用动物丝蛋白进行人工纺丝的历史和现状,从再生蜘蛛丝蛋白、重组蜘蛛丝蛋白和再生蚕丝蛋白等方面进行综述,比较了天然动物丝和人工丝纤维的力学性能,并且探讨了人工生物模拟纺丝制备高性能人工丝纤维(超级纤维)的前景。     

从天然动物丝到丝蛋白基材料的研究

作为具有优异综合力学性能的天然蛋白质纤维,丰产的动物丝特别是蚕丝长期伴随着人们的日常生活,近十余年来,各种具有特色的功能性丝蛋白基材料更是层出不穷.但在探索动物丝和丝蛋白基材料的过程中,动物丝纤维是经由蚕或蜘蛛等动物的纺器而纺制得到的简单事实往往被忽视;换言之,动物丝实际上是动物对丝蛋白进行体内“加工”后的产物,也是丝蛋白基材料中的一种.因此,天然动物丝中独特的各等级间构效关系与丝蛋白基材料的构效关系之间并不存在着必然的传承效应.本文着重介绍了我们在对动物丝和丝蛋白基材料探索中的经验和体会,即在强调以丝蛋白分子链结构与性能及其之间的关系为研究重点的基础上,从比较和发掘各种天然动物丝的特性入手,进而了解丝蛋白分子链在本体和溶液中的行为,并通过对动物丝蛋白分子链聚集态结构的调控,以达到设计制备一系列多形貌和多功能的动物丝蛋白基材料的目的.     

蜘蛛与蚕的人工强制纺丝研究进展

为制备高性能人造蜘蛛丝和蚕丝,人们在蜘蛛丝蛋白的基因重组、再生蜘蛛丝蛋白或蚕丝蛋白的仿生纺丝,以及蜘蛛与蚕的人工强制纺丝方面开展了大量工作.研究了人工强制纺丝,比较了蜘蛛牵引丝和蚕丝在不同纺丝条件下的力学性能.结果表明:在一定范围内增加纺丝速率有利于提高蜘蛛丝和蚕丝的力学性能,此外,环境温度、纺丝状态等条件对丝的性能也...     

Thermal properties of bombyx mori and several wild silkworm silks Phase transition of liquid silk

The thermal properties of liquid silk from domestic and wild silkworms are investigated. Liquid silks obtained from the silk gland of the domesticated silkworm, Bombyx mori and four wild silkworms, Samia cynthia ricini, Dictyoploca japonica, Antheraea pernyi and Antheraea yamamai were used. The DSC curves for the liquid silk from the domestic silkworm have weak endothermic peaks corresponding to the breaking of hydrogen bonds in the β-form or to the untangling of physical network. The DSC curves for the wild silkworm silks, however, show clear exothermic peaks corresponding to a phase transition from the α-helix conformation to the β-form. Liquid silk from all the different silkworms undergoes a characteristic irreversible phase transition. This revised version was published online in July 2006 with corrections to the Cover Date.     

马铃薯膳食纤维的结构特征分析

用水蒸汽爆破和氧化法对马铃薯废渣(PR)进行处理,制备马铃薯膳食纤维(PDF),并用红外光谱法、扫描电镜、热重及化学分析等方法对膳食纤维进行表征。结果表明,经过一系列的物理与化学处理,马铃薯渣中的半乳聚糖在蒸汽爆破下由长链断成短链,且由原来的块状变成片状、无规则的空间网层结构,断链的半乳糖醛基在氧化作用下生成羧基;所得到的PDF具有比表面积大、热力学稳定等特点。研究了PDF对胆固醇吸附性能。结果表明PDF对胆固醇的吸附量为1.4mg/g左右,其吸附机理符合Freundlich模式。马铃薯膳食纤维在生物体内对致病物质有一定的吸附作用。     

蚕丝中蛋白构象含量与其力学性质间的关系

丝蛋白 (Ｆｉｂｒｏｉｎ)是一种具有优异力学性能的天然有机高分子材料 ,蚕丝是最具代表性的一种 .它既有较高的强度 ,又有较强的韧性 ,其强度甚至超过钢丝 .但蚕丝具有如此优异力学性能的机理还不很清楚[1～ 3 ] .通常认为在丝蛋白中有 3种二级结构 (构象 ) ,即α 螺旋 (α ｈｅｌｉｘ) ,β 片层 ( β ｓｈｅｅｔ)和无规线团 (Ｒａｎｄｏｍｃｏｉｌ) [4,5] .α 螺旋是由链内氢键引起的蛋白结构 ,而 β 片层是由链间氢键引起的蛋白结构 .但有研究表明[3 ,6] ,丝蛋白中还存在另一种由 4个氨基酸残基组成的发夹式结构 :β 转角 ( β ｔｕｒｎ)…     

Differential Scanning Calorimetry of Native Silk Feedstock

Native silk proteins, extracted directly from the silk gland prior to spinning, offer access to a naturally hydrated protein that has undergone little to no processing. Combined with differential scanning calorimetry (DSC), it is possible to probe the thermal stability and hydration status of silk and thus investigate its denaturation and solidification, echoing that of the natural spinning process. It is found that native silk is stable between ?10 °C and 55 °C, and both the high‐temperature enthalpy of denaturation (measured via modulated temperature DSC) and a newly reported low‐temperature ice‐melting transition may serve as useful quality indicators in the future for artificial silks. Finally, compared to albumin, silk's denaturation enthalpy is much lower than expected, which is interpreted within a recently proposed entropic desolvation framework which can serve to unveil the low‐energy aquamelt processing pathway.     

Silk layering as studied with neutron reflectivity

Neutron reflectivity (NR) measurements of ultrathin surface films (below 30 nm) composed of Bombyx mori silk fibroin protein in combination with atomic force microscopy and ellipsometry were used to reveal the internal structural organization in both dry and swollen states. Reconstituted aqueous silk solution deposited on a silicon substrate using the spin-assisted layer-by-layer (SA-LbL) technique resulted in a monolayer silk film composed of random nanofibrils with constant scattering length density (SLD). However, a vertically segregated ordering with two different regions has been observed in dry, thicker, seven-layer SA-LbL silk films. The vertical segregation of silk multilayer films indicates the presence of a different secondary structure of silk in direct contact with the silicon oxide surface (first 6 nm). The layered structure can be attributed to interfacial β-sheet crystallization and the formation of well-developed nanofibrillar nanoporous morphology for the initially deposited silk surface layers with the preservation of less dense, random coil secondary structure for the layers that follow. This segregated structure of solid silk films defines their complex nonuniform behavior in the D(2)O environment with thicker silk films undergoing delamination during swelling. For a silk monolayer with an initial thickness of 6 nm, we observed the increase in the effective thickness by 60% combined with surprising decrease in density. Considering the nanoporous morphology of the hydrophobic silk layer, we suggested that the apparent increase in its thickness in liquid environment is caused by the air nanobubble trapping phenomenon at the liquid-solid interface.     

Comparative thermal analysis of Eri,Mori, Muga,and Tussar silk cocoons and fibroin fibers

Wild silks are often extremely durable and have many advantages over the domesticated silk. In this study, three kinds of wild silks—Indian Antheraea mylitta (Tussar), Antheraea assama (Muga), and Philosamia ricini (Eri) silkworm cocoons were successfully degummed and their thermal properties were studied comparatively with domesticated Chinese mulberry (Bombyx mori) silkworm cocoons and fibers. Advanced thermal analysis methods, such as differential scanning calorimetry (DSC) and temperature-modulated DSC were utilized to identify glass transition temperatures (T _g), heat capacity increments at T _g, and degradation temperatures of these silk materials. In addition, the bound water contents and the thermal degradation mechanisms of different silk systems were also quantified using thermogravimetric analysis. Compared with the mulberry silk materials, wild silk materials showed higher thermal stabilities, and variable degradation profiles. These comparative methods would offer a new pathway to understand the physical properties of silk-based biomaterials, such as their tunable thermal, mechanical, optical, and electrical properties. And it could provide useful insights for the development of new silk-based medical devices and sutures with controllable biological functions in the future.