【作者】 王洪；

【导师】 胡学超；

【作者基本信息】 东华大学 ， 材料科学与工程， 2005， 博士

【摘要】 本文简要介绍了仿生纺蜘蛛丝技术的研究现状,总结了人工纺丝的技术路线和所得纤维的基本性能。同时,我们从以下二个角度进行了思考,即:转基因蜘蛛丝蛋白水溶液或再生蚕丝素蛋白水溶液中丝素蛋白分子的构象结构与蜘蛛或蚕腺体内是否相同?是否需要“仿生制备纺丝液”?为了对以上问题进行解答,本文以家蚕的丝素蛋白质为模型对模仿生物体成丝过程的仿生纺丝技术进行了一些探索性的研究。我们制备了高浓度的再生蚕丝素蛋白水溶液,并首次研究了它的流变性能及剪切作用下的构象变化,同时还对它的存放稳定性进行了研究。为了弄清楚拉伸对再生丝素蛋白水溶液结构变化的影响,我们运用静电纺丝方法对再生丝素蛋白水溶液进行了纺丝试验,以寻找丝素蛋白转化为纤维的条件。结果发现静电纺所得纤维的结构是介于无定型和蚕丝之间的,尽管静电纺丝有非常高的拉伸倍数,但所得纤维还是达不到如蚕丝般的结构。为此,我们对再生丝素蛋白水溶液与蚕腺体内丝素蛋白水溶液进行了对比分析,发现浓再生丝素蛋白水溶液与蚕腺体内丝素蛋白水溶液的性能是有差别的,从而提出了“仿生纺丝”之前,首先要“仿生制备纺丝液”的新观点。 本文摸索出了制备高浓度再生丝素蛋白水溶液的方法,并研究了浓再生丝素蛋白水溶液的流变性能和在剪切作用下的构象结构变化,结果发现:(1)再生丝素蛋白水溶液的流变性能和常规聚合物浓溶液的流变性能差别很大。首先,它的切力变稀现象随溶液的浓度的增加而变弱;其次,溶液粘度非常小。(2)再生丝素蛋白浓水溶液的零切粘度随浓度的增加而增加,在35%左右达到最大值,浓度再提高粘度下降。但在粘度下降条件下仍然观察不到各向异性现象。(3)高浓度的再生丝素蛋白水溶液经过剪切作用后呈现出各向异性的性质,相同浓度下,剪切作用越大,再生丝素蛋白水溶液越容易实现由各向同性到各向异性的转变;相同剪切作用时,再生丝素蛋白水溶液的浓度越高,经剪切作用后,溶液的各向异性的性质越明显。(4)再生丝素蛋白水溶液经剪切作用后,丝素蛋白分予构象发生了由无规线团/α螺旋结构到β—折叠结构的转变。再生丝素蛋白水溶液的流变性能和常规聚合物浓溶液的流变性能差别很大。东平大李博士论文摘要 经过对高浓度再生丝素蛋白水溶液流动稳定性的研究发现,丝素蛋白水溶液是一种不稳定的体系,存在存放流动稳定性问题。随着溶液浓度和存放温度的升高,溶液的流动稳定性迅速下降,最终使体系发生凝胶化。其中当溶液浓度小于27%时,浓度对流动稳定性的影响较大,浓度越低流动稳定性越好。而当浓度高于27%后,溶液的流动稳定性迅速下降,浓度的影响也大大降低。丝素蛋白水溶液对环境温度非常敏感,当温度低于25℃时,溶液的凝胶化速度较慢;而当温度升高后,溶液的凝胶化速度迅速加快,在60℃时只需半小时就凝胶化。蚕吐丝时,其中部丝腺内丝素蛋白水溶液的浓度在30%左右,温度为25℃左右的春天和秋天,这一吐丝条件也是充分利用了丝素蛋白的流动稳定性。在制备丝素蛋白纺丝水溶液时,应先把最初的转基因或再生丝素蛋白稀水溶液存放在低温下,然后在纺丝前进行浓缩,这样就可以得到稳定的丝素蛋白纺丝用水溶液。 为了弄清楚拉伸对再生丝素蛋白水溶液结构变化的影响,我们运用静电纺丝方法,对再生丝素蛋白水溶液进行了纺丝试验,发现可以从丝素蛋白水溶液中制得念珠状的、圆形的或带状的超细丝纤维,纤维的直径在100 nm到900nm之间,平均为7O0nm。当纺丝液浓度为28%、电压为ZKV、喷射距离为11 cm时,可制得具有光滑表面的圆形丝纤维。拉曼光谱检测的结果发现,所得的静电纺丝纤维中已含有p折叠结构。DSC和X光衍射结果表明静电纺丝纤维不是无定型结构,但也不是和天然蚕丝一样的p一折叠结构。通过计算发现,静电纺丝时纤维经历了非常高的拉伸比,并和蚕吐丝的条件相当,但即使这样也无法得到与蚕丝相同的结构;而静电纺丝纤维大的比表面积和蚕以慢的吐丝速度都是起到使溶液中的水分挥发的作用。试验表明,只有当溶液的浓度足够高,使丝素蛋白分子之间形成有效的缠结;并对丝素蛋白水溶液加以足够高的拉伸力,使丝素蛋白分子拉伸取向;同时保证溶液中的水分快速有效地挥发,才有可能形成丝纤维。但要使该纤维结构与蚕丝相同尚需其他条件配合。 通过对再生蚕丝素蛋白水溶液与天然蚕腺体内丝素蛋白水溶液的性能对比分析发现,再生蚕丝素蛋白水溶液和天然蚕腺体内丝素蛋白水溶液的性能差别非常大。再生蚕丝蛋白分子量与蚕腺体内丝素蛋白分子量相差不大,但蚕腺体内丝素蛋白水溶液的零切粘度要比再生丝素蛋白水溶液高得多,尽管它们的浓度相当。这说明蚕毯更多还原

【Abstract】 In this thesis, the development of biomimetic spider and silkworm silk has been briefly introduced. The processes and properties of resultant man-made silk fiber have also been summarized. It is found two key issues are not discussed yet. Whether the conformation of silk fibroin in regenerated solution or in the silkworm gland is the same or not? Whether it is necessary to prepare the spinning solution by a biomimetic process? In our work, silk fibroin of silkworm is selected as a model system because there is still not enough spider silk protein that can be supplied to do spinning and on the other side, the composition of silkworm fibroin is very similar to spider protein. In order to answer the above questions, the concentrated regenerated silk fibroin aqueous solution was prepared first, it’s structure and properties of rheology and flow stability were studied. After that, the electrospin process was applied on regenerated concentrated silk fibroin aqueous solution in order to find out the conditions to form silk fiber from silk fibroin aqueous solution. It is found a kind of silk fiber can be got, but the structure of this kind silk fiber is between amorphous film and nature silk. The difference between the structure and properties of silk fibroin in regenerated aqueous solution and in vivo was further studied. The main conclusions are as follows.Viscous, transparent, homogeneous and spinnable silk fibroin aqueous solutions with high silk fibroin content were first prepared. The rheological behaviors of solutions with different concentration were studied by HAAKE RS150 rheometer. There is a rapid initial shear thinning at low shear rates (<10 s-1) for regenerated silk fibroin aqueous solutions with low concentration. However, the shear-thinning phenomenon becomes not obvious with the increase of the solution concentration, which is different from ordinary polymer solution. With the increase of concentration, the macromolecule chain become more and more compacted, the entanglements in solution increase not very quickly. As a result, the viscosity of solution is not very high.The zero shear viscosity is increasing with the concentration of regenerated silk fibroin aqueous solution and reaches max in 35%, then decreases. But all these solutions are isotropic. Only with shear the solution becomes anisotropic. With the increase ofconcentration, the birefringent or anisotropic phenomenon becomes easier under the same shear rate. Similarly, with the same concentration, the anisotropic phenomenon becomes more and more obvious with the increase of shear rate. Raman spectroscopy analysis showed that the structure of silk fibroin has changed from random coil and/or a helix into β-sheet by shear.The study on the flow stability of regenerated silk fibroin aqueous solutions with different concentrations under different temperatures indicates that the flow stability decreases quickly with the increase of solution concentration and temperature. X-ray diffraction, Fourier transform infrared (FTIR) and Raman spectroscopy analysis show that silk fibroin in regenerated aqueous solution is mainly in random coil conformation. However, it turns into a helix and p-sheet conformation after gelation, and both silk I and silk II structure appears accordingly. The key concentration and key temperature for the flow stability of regenerated silk fibroin aqueous solution are about 27wt% and 25°C, respectively. Silkworms in the nature may possibly make full use of this rule. The investigation implies that the original dilute regenerated or recombinant silk fibroin aqueous solution should be stored under low temperature and concentrated just before spinning.By using electrospinning technique, beaded, cylinder shaped or ribbon like ultra-fine silk fibroin fibers are obtained from regenerated concentrated silk fibroin aqueous solution under different processing conditions. These fibers have an average diameter of 700 nm. It is found that the morphology and the secondary structure of the as-spun silk fibroin fibers are strongly influenced by the更多还原