全生物质α-甲壳素纳米纤维柔性透明膜的制备及性能研究

Preparation and Properties of Flexible,Transparent,All-biomassα-Chitin Nanofiber Films

在自然界中,甲壳素一般以有序的结晶纳米纤维形式存在,赋予了生物体优异的力学性能。本研究分别采用“常温温和”(常温,Mild condition)和“高温加热”(高温,High temperature condition)两种方法从废弃蟹壳中提取α-甲壳素并制得常温α-甲壳素纳米纤维膜(常温膜)和高温α-甲壳素纳米纤维膜(高温膜),分别对所得两种α-甲壳素纳米纤维样品从微观结构、力学性能、结晶构造、表面特性以及光学性能等方面进行表征,分析对比两种不同提取方法对甲壳素纤维结构及性能的影响,并进一步探究提取制备过程中甲壳素的纤维形态及均匀性对其薄膜力学性能、光学透明性的影响。结果表明,与“高温”提取条件相比,经“常温”条件提取所得α-甲壳素纳米纤维具有较高的长径比且尺寸分布均匀,较好地保留了甲壳素原有的天然结构。其中,常温膜的拉伸强度可达(152±2.56) MPa,断裂伸长率约为10.0%,是高温膜的2.50倍左右,具有较好的柔韧性。同时,常温膜还具备优异的光学及热稳定性能,透光率高达91.0%,雾度低至3.19%,在200℃高温条件下仍能保持性状稳定。综上,“常温”条件下提取的甲壳素纳米纤维由于较好地保留了其天然结构优势,使得制备所得膜材料具备优异的力学强度及透光性等。本工作的研究成果为制备全生物质高强度、低雾度柔性透明膜材料提供了理论依据和技术支持,有望作为柔性透明基材应用于柔性电子元件、电子皮肤、智能标签及柔性传感等研究领域。

In nature,chitin generally exists in the form of ordered crystalline nanocrystalline fibers,which gives organisms excellent mechanical properties.In this study,chitin was extracted from discarded crab shells by two methods of‘mild condition’and‘high temperature condition’,respectively.Then the room temperatureα-chitin nanofiber films(mild condition film)and the high temperatureα-chitin nanofiber films(high temperature condition film)were prepared by vacuum filtration through mechanical grinding and other processing methods.To further discuss the influence of the nanofiber morphology and uniformity on the film mechanics,optical transparency,the microstructural morphology,mechanical tensile properties,crystal structure,surface characteristics,optical properties and thermal performance of the prepared chitin nanofiber films were characterized.The results show that,compared with the extraction of‘high temperature condition’,theα-chitin nanofibers extracted under the‘mild condition’have higher aspect ratio and uniform size distribution,and retain the excellent original natural structure of chitin.Among them,the mild condition films have good flexibility,whose tensile strength can reach(152±2.56)MPa,and the elongation at break is nearly 10.0%,which is about 2.50 times than that of the high temperature condition films.At the same time,the mild condition films also have excellent optical and thermal stability,with the light transmittance as high as 91.0%and the haze as low as 3.19%,and it can still maintain stable properties at 200℃.Thus,chitin nanofiber extracted under the“mild condition”retains its natural structural advantages,which contribute to the film excellent mechanical strength and light transmittance.The research results in this work provide theoretical basis and technical support for the preparation of all-biomass flexible transparent film materials with high strength and low haze,and are expected to be used as flexible transparent substrates in the research fields of flexible electronics components,electronic skin,smart tags and flexible sensors,etc.