弥漫分散剂/粒子绑定机制反射红外光谱鉴定功能性油墨
Summary
Formulation of stable, functional inks is critical to expanding the applications of additive manufacturing. In turn, knowledge of the mechanisms of dispersant/particle bonding is required for effective ink formulation. Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) is presented as a simple, inexpensive way to gain insight into these mechanisms.
Abstract
In additive manufacturing, or 3D printing, material is deposited drop by drop, to create micron to macroscale layers. A typical inkjet ink is a colloidal dispersion containing approximately ten components including solvent, the nano to micron scale particles which will comprise the printed layer, polymeric dispersants to stabilize the particles, and polymers to tune layer strength, surface tension and viscosity. To rationally and efficiently formulate such an ink, it is crucial to know how the components interact. Specifically, which polymers bond to the particle surfaces and how are they attached? Answering this question requires an experimental procedure that discriminates between polymer adsorbed on the particles and free polymer. Further, the method must provide details about how the functional groups of the polymer interact with the particle. In this protocol, we show how to employ centrifugation to separate particles with adsorbed polymer from the rest of the ink, prepare the separated samples for spectroscopic measurement, and use Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) for accurate determination of dispersant/particle bonding mechanisms. A significant advantage of this methodology is that it provides high level mechanistic detail using only simple, commonly available laboratory equipment. This makes crucial data available to almost any formulation laboratory. The method is most useful for inks composed of metal, ceramic, and metal oxide particles in the range of 100 nm or greater. Because of the density and particle size of these inks, they are readily separable with centrifugation. Further, the spectroscopic signatures of such particles are easy to distinguish from absorbed polymer. The primary limitation of this technique is that the spectroscopy is performed ex-situ on the separated and dried particles as opposed to the particles in dispersion. However, results from attenuated total reflectance spectra of the wet separated particles provide evidence for the validity of the DRIFTS measurement.
Introduction
添加剂制造近来成为一个有前途的技术，一切从陶瓷半导体制造医疗器械1。作为添加剂制造的应用扩大到印刷陶瓷，金属氧化物，和金属零件，需要制定专门功能性油墨产生。如何制定所需的功能性油墨的问题涉及到一个根本性的问题，表面和胶体科学：什么是由胶体粒子分散体是稳定的防止聚集的机制？广泛地说，稳定化需要，从而防止颗粒（和因此聚合）的附近的方式或者通过库仑斥力（静电稳定化），由聚合物缠结（空间稳定）的熵惩罚，或由库仑的组合的颗粒表面的变形和熵力（电空间稳定）2。为了实现任何的这些机制稳定化，通常需要通过附着聚合物或较短链的官能团进行修改的粒子表面的化学反应。因此，稳定的功能性油墨的合理配方要求我们知道给定的化学添加剂是否附着到颗粒表面和什么化学基团附着到颗粒表面。
在这个协议中提出的方法的目的是要证明在功能性油墨吸附在颗粒表面的化学物种的快速鉴定。这个目标是从表面和胶体科学家科学家和感兴趣印刷陶瓷，金属氧化物和金属设备工程师的范围广泛的实践活性的专门任务官能油墨制剂跃迁特别重要。实现这一目标，需要设计一种克服表征不透明，高固体负载分散体的挑战的实验。它还需要鉴别通道之间emical物种中存在的分散体，但不吸附在从那些实际吸附的颗粒。它还需要被化学吸附在从那些弱物理吸附的颗粒的那些物种之间进行区分。在这个实验方案，我们提出利用漫反射红外光谱仪对分散剂附着在功能性油墨的特性。漫反射红外光谱测量如下必要区分吸附物质从那些仅仅存在于分散体中的分析前的样品制备技术。
多种方法目前用于洞察化学油墨组分和胶态分散颗粒之间的相互作用的性质。一些这些方法是间接的探针，其中测得特性被假定为关联与表面官能化。例如，改变泥浆流变性或沉淀 – [R阿泰被推定与相关吸附表面改性剂3。粒径分布，作为其特征在于通过动态光散射（DLS），和ζ电位，为特征的电泳迁移率，提供深入了解聚合物或物种的表面电荷4,5的吸附。同样地，采样的质量损失为探测由热重量分析（TGA）涉及解吸物质的存在和被吸附物和粒子6之间的相互作用的强度。从上面提到的间接探针的信息表明改变表面化学性质，但它们不提供直接洞察吸附物种的身份，或它的吸附机理。直接洞察为功能性油墨，其中，大量的部件都存在于分散体特别重要。为了提供更详细的分子水平信息，X射线光电子能谱（XPS）7，13 C核磁振（NMR）4,6，和红外光谱8-12已探索。这三个选项中，红外光谱法是特别有前途。在比较13 C-NMR，红外光谱不需要油墨，分析纯溶剂进行配制，以防止测量13过程中的干扰。相比于X射线光电子能谱，标准红外光谱可以在环境压力下进行，避免了需要在测量过程中超高真空条件。
有文献先例利用红外光谱探测胶态分散陶瓷，金属氧化物，和金属纳米粒子之间的相互作用。这些作品可以分离成尝试使用衰减全反射红外（ATR-IR）的9到测量原位界面化学，并尝试使用固体采样8以测量界面化学易地 。 W¯¯往往微不足道有优势现场测量，出现由于需要进行光谱操作的不确定性使该方法难以用于多组分的油墨，其中有溶剂和多种聚合物组分。因此，该协议侧重于固体取样和易地测量。所有的固体采样方法需要在那里的固体通过从溶剂中分离出的颗粒而得到的前处理步骤，并在红外线测量上的固体颗粒进行的分析步骤。方法之间的不同是在样品前处理的选择和在用于固体的红外分析实验技术的选择。在历史上，传统的方式来使用红外光谱来分析固体含量为研磨少量用溴化钾（KBr压）粉末固体样品的（<1％），然后经受混合物以高压烧结。其结果是透明KBr压片。该公关ocedure已成功地尝试与来自官能化聚乙烯胺10氧化锆纳米粒子的水性悬浮液，用脂肪酸单层钴纳米颗粒7的粉末，并与对Fe 3 O 4纳米颗粒14儿茶酚衍生的分散剂。尽管检测吸附的分散剂的溴化钾造粒技术的这些成功的应用，漫反射红外光谱提供了几个优点。一个优点是简化了样品制备。在对比溴化钾造粒，在漫反射固体样品可以简单地用手工研磨。不存在烧结步骤作为本身被装入样品杯和漫散射的红外光进行测量的粉末。漫反射在KBr压造粒的另一优点是增加的表面灵敏度15。在表面灵敏度的增加是对于本申请特别有用，其中，CRI蒂卡尔问题是存在和吸附物的性质的纳米颗粒的表面上。
在已经使用了漫反射采样技术来探测在胶态分散的样品的化学物质的吸附作品，一次差值出现在从液体介质中分离出纳米颗粒的方法。这个步骤是关键的，因为如果没有分离，这将是不可能区分从分散剂简单地溶解在液体介质中特殊吸附分散剂。在几个实例中，分离的方法，没有从实验方案12,16,17明显。当指定时，最常采用的方法包括重力分离。的理由是，陶瓷，金属氧化物，以及金属纳米颗粒的所有比周围介质更加密集。当他们定居，他们将拖累他们只特异性吸附物种。化学物质不与部分交互icles将留在溶液中。虽然可能分散在正常重力18随手解决，稳定的喷墨油墨不宜observably解决在不到一年的时间。因此，优选采用离心预分析分离的方法。这已被证明在分散剂吸附的几项研究对玻璃微粒19,20，在氧化铝上的8分散剂粘合剂吸附和CuO 11的阴离子分散剂官能化。最近，我们用它来 评估的脂肪酸中使用的固体氧化物燃料电池层21的喷墨和气溶胶喷射印刷的非水氧化镍分散体结合的机制。
Protocol
Representative Results
Discussion
的两个关键因素的产生高品质的红外光谱使用此过程是：1）最小化水的污染的绝对量和在样品和参比杯之间的水的污染的量的差异;和2）创建样本和参照杯具有均匀平坦层和类似溴化钾晶粒尺寸。这两个因素都受到特别注意在2.3节所列的样品制备程序来实现的。
为了最大限度地减少水的污染的总量，并保持水的污染的参比和样品相同，有必要尽量减少时间，该吸湿溴化钾是?…
Divulgazioni
The authors have nothing to disclose.
Acknowledgements
作者承认空军研究实验室的下UES分包合同＃S-932-19-MR002的支持。作者进一步确认设备的支持来自纽约州研究生研究和教学计划（GRTI / GR15）。
Materials
| FTIR bench | Shimadzu Scientific Instruments | IR_Prestige 21 used in this work; in 2013 IR-Tracer 100 model replaced Prestige-21 | Any research grade FTIR with purgable sample compartment is acceptable |
| Purge gas generator for sample compartment | Parker Balston | 74-5041NA Lab Gas Generator | Provides air with less than 1ppm CO2 and water; also possible to purge compartment with N2 tank |
| Diffuse Reflectance Infrared Accessory | Pike Technologies | 042-10XX | Includes sample preparation kit and mortar and pestle (these can also be purchased separately, described below) |
| Diffuse Reflectance Sample Preparation kit | Pike Technologies | 042-3040 | Includes sample holder cups, spatulas, alignment mirror, mirror brush, razor blades |
| Agate mortar and pestle | Pike Technologies | 161-5035 | |
| Centrifuge | ThermoScientific | Sorvall ST16 | Most benchtop centrifuges capable of ~ 5000 rpm will be acceptable |
| Consumables | |||
| Item | Company | Catalog # | Comments/Description |
| Centrifuge tubes | Evergreen Scientific | 222-2470-G8K | Any centrifuge tube of compatible size and material is acceptable |
| KBr powder packets | ThermoScientific | 50-465-317 | Also possible to use alternative KBr supplier |
Riferimenti
- Wray, P. Additive manufacturing- Turning manufacturing inside out. American Ceramic Society Bulletin. 93, (2014).
- Hiemenz, P. C., Rajagopalan, R. . Principles of Colloid and Surface Chemistry, Third Edition, Revised and Expanded. , (1997).
- Böhnlein-Mauß, J., et al. The function of polymers in the tape casting of alumina. Advanced Materials. 4, 73-81 (1992).
- Grote, C., Cheema, T. A., Garnweitner, G. Comparative Study of Ligand Binding during the Postsynthetic Stabilization of Metal Oxide Nanoparticles. Langmuir. 28, 14395-14404 (2012).
- Zhang, Q., et al. Aqueous Dispersions of Magnetite Nanoparticles Complexed with Copolyether Dispersants: Experiments and Theory. Langmuir. 23, 6927-6936 (2007).
- Amstad, E., Gillich, T., Bilecka, I., Textor, M., Reimhult, E. Ultrastable Iron Oxide Nanoparticle Colloidal Suspensions Using Dispersants with Catechol-Derived Anchor Groups. Nano Letters. 9, 4042-4048 (2009).
- Wu, N., et al. Interaction of Fatty Acid Monolayers with Cobalt Nanoparticles. Nano Letters. 4, 383-386 (2004).
- Blackman, K., Slilaty, R. M., Lewis, J. A. Competitive Adsorption Phenomena in Nonaqueous Tape Casting Suspensions. Journal of the American Ceramic Society. 84, 2501-2506 (2001).
- Hind, A. R., Bhargava, S. K., McKinnon, A. At the solid/liquid interface: FTIR/ATR — the tool of choice. Advances in Colloid and Interface Science. 93, 91-114 (2001).
- Wang, J., Gao, L. Surface properties of polymer adsorbed zirconia nanoparticles. Nanostructured Materials. 11, 451-457 (1999).
- Guedes, M., Ferreira, J. M. F., Ferro, A. C. A study on the aqueous dispersion mechanism of CuO powders using Tiron. Journal of Colloid and Interface Science. 330, 119-124 (2009).
- Guedes, M., Ferreira, J. M. F., Ferro, A. C. Dispersion of Cu2O particles in aqueous suspensions containing 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt. Ceramics International. 35, 1939-1945 (2009).
- Gottlieb, H. E., Kotlyar, V., Nudelman, A. NMR Chemical Shifts of Common Laboratory Solvents as Trace Impurities. The Journal of Organic Chemistry. 62, 7512-7515 (1997).
- Amstad, E., et al. Influence of Electronegative Substituents on the Binding Affinity of Catechol-Derived Anchors to Fe3O4 Nanoparticles. The Journal of Physical Chemistry C. 115, 683-691 (2010).
- Naviroj, S., Koenig, J. L., Ishida, H. Diffuse Reflectance Fourier Transform Infrared Spectroscopic Study of Chemical Bonding and Hydrothermal Stability of an Aminosilane on Metal Oxide Surfaces. The Journal of Adhesion. 18, 93-110 (1985).
- Li, C. -. C., Chang, M. -. H. Colloidal stability of CuO nanoparticles in alkanes via oleate modifications. Materials Letters. 58, 3903-3907 (2004).
- Lee, S., Paik, U., Yoon, S. -. M., Choi, J. -. Y. Dispersant-Ethyl Cellulose Binder Interactions at the Ni Particle-Dihydroterpineol Interface. Journal of the American Ceramic Society. 89, 3050-3055 (2006).
- Lee, S. J., Kim, K. Diffuse reflectance infrared spectra of stearic acid self-assembled on fine silver particles. Vibrational Spectroscopy. 18, 187-201 (1998).
- Lee, D. H., Condrate, R. A. FTIR spectral characterization of thin film coatings of oleic acid on glasses: I. Coatings on glasses from ethyl alcohol. Journal of Materials Science. 34, 139-146 (1999).
- Lee, D. H., Condrate, R. A., Lacourse, W. C. FTIR spectral characterization of thin film coatings of oleic acid on glasses Part II Coatings on glass from different media such as water, alcohol, benzene and air. Journal of Materials Science. 35, 4961-4970 (2000).
- Jay Deiner, ., Piotrowski, L., A, K., Reitz, T. L. Mechanisms of Fatty Acid and Triglyceride Dispersant Bonding in Non-Aqueous Dispersions of NiO. Journal of the American Ceramic Society. 96, 750-758 (2013).
- Young, D., et al. Ink-jet printing of electrolyte and anode functional layer for solid oxide fuel cells. Journal of Power Sources. 184, 191-196 (2008).
- Nakamoto, K. . Infrared and Raman Spectra of Inorganic and Coordination Complexes. , (1997).
- Fuller, M. P., Griffiths, P. R. Diffuse reflectance measurements by infrared Fourier transform spectrometry. Analytical Chemistry. 50, 1906-1910 (1978).
