Novel Biodegradable Materials for Additive Manufacturing of Complex Scaffolds for Algal Bioremediation Systems

藻类养殖已经引起了环境修复和能源生产应用的极大兴趣。然而，在这些应用中使用藻类的经济可行性在很大程度上取决于种植特定藻类类型的效率。定制设计的材料和结构允许控制微生物生长过程，从而提高水修复和能量收集的效率。传统上，二维合成聚合物网被用作藻类附着和生长的支架。这些传统的基质不能生物降解，也不能为藻类生长提供最佳的形状或表面特征。该奖项支持使用增材制造技术从纤维素纳米晶体中打印可生物降解复合材料支架的基础研究，纤维素纳米晶体是从废弃的农业和森林产品中提取的天然丰富材料。研究结果将有助于发展更经济和可生物降解的途径来种植藻类，以去除水中的污染物和/或产生能源。本研究的总体目标是建立对水修复反应器中支架组成、形状和质地对藻类生长和支架生物降解的综合影响的科学理解。第一个研究目标是了解材料组成和加工对长丝性能的影响。为了实现这一目标，纤维素纳米晶/聚乳酸复合长丝将经过三种初始混合方法的挤压生产：1)干燥混合，2)喷雾干燥，3)聚乙烯氧化物/纤维素纳米晶母粒掺入。流变、热、形态和接触角性能的测量将使用标准方法进行。第二个目标是了解长丝的流变特性（特别是弹性模量与粘性模量的比率）对增材制造（熔融沉积建模）打印的支架质量（包括表面缺陷）的影响。几种类型的复合长丝将被打印成含有一系列表面结构的藻类生长支架。沉积层的特征（如层厚度、道路宽度和填充空隙）将使用光学显微镜和彩色共聚焦轮廓术测量，并与表面缺陷相关联。第三个目标是了解支架形状和化学如何影响藻类生长和支架降解。这些支架将被放入一个含有藻类生长介质的实验室规模的流动反应器中。在一个星期的增量，支架将被移除，并通过光学显微镜检查。然后将藻类移除，并记录从不同地区收获的大量藻类。还将使用显微镜和质量测量来评估支架的变化。

Algal farming has garnered significant interest for both environmental remediation and energy production applications. However, the economic viability of using algae for these applications heavily depends on the efficiency of growing specific algae types. Custom-designed materials and structures allow for controlled microbiological growth processes that result in increased efficiency in water remediation and energy harvesting. Conventionally, two-dimensional synthetic polymer meshes are employed as the scaffolds for algal attachment and growth. These traditional substrata are not biodegradable, and do not provide the optimal shape or surface characteristics for targeted algal growth. This award supports fundamental research on using additive manufacturing to print biodegradable composite scaffolds from cellulose nanocrystals, naturally abundant materials extracted from waste agricultural and forest products. Research results will help advance the development of more economical and biodegradable routes to grow algae for removing contaminants from water and/or producing energy. The overarching goal of this research is to establish a scientific understanding of combined effects of scaffold composition, shape, and texture on algal growth and scaffold biodegradation in water remediation reactors. The first research objective is to understand the effects of the material composition and processing on the filament properties. To achieve this objective, cellulose nanocrystal/polylactic acid composite filaments will be produced using extrusion after three initial mixing methods: 1) dry mixing, 2) spray drying, and 3) polyethylene oxide/cellulose nanocrystal masterbatch incorporation. Measurement of rheological, thermal, morphological, and contact angle properties will be performed using standard methods. The second objective is to understand the effects of rheological properties (particularly the ratio of the elastic to viscous modulus) of the filaments on the quality (including surface defects) of the scaffolds printed by additive manufacturing (fused deposition modeling). Several types of composite filament will be printed into algae growth scaffolds containing a range of surface structures. The characteristics of the deposited layers (e.g. layer thickness, road width, and fill voids) will be measured using optical microscopy and chromatic confocal profilometry and correlated to surface defects. The third objective is to understand how scaffold shape and chemistry affect algal growth and scaffold degradation. The scaffolds will be put into a laboratory-scale flow reactor containing algae growth media. At one week increments, the scaffold will be removed and examined by optical microscopy. The algae will then be removed and the mass harvested from different regions recorded. Changes to the scaffold will also be assessed using microscopy and mass measurement.