GOALI: Determination of the Structure and Properties of Microfibrillated Cellulose during Dynamic Phase Transitions

微纤化纤维素（MFC）是造纸过程中产生的废品。 它经过商业加工用于某些工业用途，但它也具有作为消费品、织物和家庭护理产品中的流变改性剂的潜在应用。 流变改性剂是添加到某些产品中以定制其流动行为的材料。 MFC 是非离子的，这使得它与多种产品配方兼容，但它必须分散在整个产品中才能改变产品的性能。 挑战在于，MFC 是以高度缠结的纤维在水中的浓缩浆料形式提供的，在大多数产品中很难分散。 这个 GOALI 项目是理海大学和宝洁公司之间的合作项目，将研究 MFC 的结构如何取决于温度、主体溶液的成分以及由于流动而施加在 MFC 上的力等参数。 研究人员使用多种探测 MFC 纤维微观结构排列的技术，探索可以增强 MFC 在有用产品中分散的微观结构转变。 将造纸工业中的 MFC 废物重新用作消费品的添加剂将减少 MFC 处置的需要，并降低有价值的消费品的制造成本。 研究团队将参与各种外展活动，包括在达芬奇科学中心开展的向公众进行胶体和流变学教育的项目，指导对 STEM 领域感兴趣的中学生和高中生，以及培训本科生和研究生进行研究。该 GOALI 项目的总体目标是表征 MFC 支架的空间和时间流变演化特征，使其能够用作消费品、织物和家庭护理产品的流变改性剂。 MFC的纤维尺寸与目前使用的流变改性剂的纤维尺寸相当，但与其他改性剂不同的是，MFC在胶体上的电荷可以忽略不计。通过使用微流变学和显微镜表征 MFC 的微观结构演化、表征 MFC 系统的体流变学演化、以及使用独特的微流体平台和多粒子跟踪微流变学确定相变后的平衡特性和支架结构，将探索 MFC 的潜在优势。 MFC 解决方案将在三个驱动力的相变过程中进行表征：温度、周围溶液的变化以及流动引起的机械力。这些知识将使这些材料能够用作配方产品行业的流变改性剂。研究结果将识别导致均匀 MFC 悬浮液的材料，并确定导致稳定悬浮液的微观结构和宏观结构和性能。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Microfibrillated cellulose (MFC) is a waste product generated during paper manufacturing. It is processed commercially for some industrial uses, but it also has a potential application as a rheological modifier in consumer, fabric and home care products. Rheological modifiers are materials added to certain products to customize their flow behavior. MFC is non-ionic, which makes it compatible with a wide range of product recipes, but it must be dispersed throughout a product to modify the product's properties. The challenge is that MFC is supplied as a concentrated slurry of highly entangled fibers in water that are difficult to disperse in most products. This GOALI project, which is a collaboration between Lehigh University and Procter and Gamble, will investigate how the structure of MFC depends on parameters such as the temperature, composition of the host solution and forces exerted on MFC due to flow. Using several techniques that probe the microstructural arrangements of the MFC fibers, the researchers explore transitions in the microstructure that can enhance dispersal of MFC in useful products. Repurposing MFC waste from the paper industry as additives for consumer products will reduce the need for MFC disposal and reduce manufacturing costs of valuable consumer products. The research team will engage in a variety of outreach activities, including programs at the Da Vinci Science Center to educate the public in colloids and rheology, mentoring middle school and high school students interested in STEM fields, and training undergraduate and graduate students in research.The overall goal of this GOALI project is to characterize the spatial and temporal rheological evolution of an MFC scaffold to enable its use as a rheological modifier for consumer, fabric and home care products. MFC has a fiber size that is comparable to the fiber size of rheological modifiers in current use, but unlike other modifiers, MFC has negligible charge on the colloid. The potential advantages of MFC will be explored by characterizing the microstructural evolution of MFC using microrheology and microscopy, by characterizing the evolution of bulk rheology of MFC systems, and by determining equilibrium properties and scaffold structure after phase transitions using a unique microfluidic platform and multiple particle tracking microrheology. MFC solutions will be characterized during phase transitions due to three driving forces: temperature, changes in the surrounding solution and flow-induced mechanical forces. This knowledge will enable the use of these materials as rheological modifiers for the formulated product industry. The results of the research will identify materials that lead to homogeneous MFC suspensions and determine the microstructure and macroscopic structure and properties that lead to stable suspensions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.