作者衷心感谢国家科学基金会 (DMR-1409034) 对该项目的支持。我们还感谢美国商务部国家标准和技术研究所的支持, 提供了这项工作所用的 USANS 设施, 其中部分由国家科学基金会根据协议予以支持。笑DMR-0944772这项研究的 san 实验是在 ORNL 的高通量同位素反应器中完成的, 该反应堆是由美国能源部的科学用户设施分部、能源科学办公室主办的。

所有化学品的处理都应使用适当的个人防护设备并在安全罩内进行。所有暴露于电离辐射的样品应在设施放射性控制技术员的监督下处理。本议定书是由已完成适当的辐射安全培训的个人执行的。
1. d-管理局溶液中 P3HT 的制备
<ol>
	<li>采集样本
	<ol>
		<li>购买1克高 regioregularity (和 #62; 90%)P3HT 在分子量范围 15-40 K。</li>
		<li>购买5克高纯度 (和 #62; 90 atom% 氘) d-4 12-管理局。</li>
	</ol>
	</li>
	<li>样品制备
	<ol>
		<li>过滤所有 d-管理局溶液与0.45 µm 筛子入一个玻璃瓶。</li>
		<li>结合0.34 克的 P3HT 在1.66 克的 d-管理局在一个5克玻璃小瓶与箔衬帽。 注: 在整个样品的创建和转移过程中, 尽量减少样品在任何时候暴露的环境光强度。</li>
		<li>在瓶子上加一个磁力搅拌棒, 盖上盖子, 然后用膜密封。</li>
		<li>包装瓶完全在铝箔, 以防止任何光线暴露在解决方案。</li>
		<li>将样品放在热板上, 70 ° c 为 1-3 h, 并启用磁性搅拌棒。</li>
		<li>一旦解决方案是完全均匀的 (最好是离开样品加热/搅拌过夜, 以确保完全分散), 除去热和搅拌。</li>
		<li>从小瓶转移到一个适当地清洗 (与分开的漂洗丙酮并且水) 1 或2毫米厚实的石英班卓琴细胞使用玻璃吸管。 注: 在加热烤箱中将玻璃吸管加热至70° c 后, 即可大大简化此过程。</li>
		<li>用膜贴上班卓琴的帽子和印章。</li>
		<li>将班卓琴细胞置于完全黑暗中 (即在密封盒内或用铝箔包裹)。</li>
		<li>在类似的方式组装一个样本, 其中只包含 d-管理局 (填充到容量) 和一个空的班卓琴细胞, 作为溶剂的背景和空细胞, 分别为散射实验。</li>
	</ol>
	</li>
</ol>
2. 中子散射实验
<ol>
	<li>"黑暗" 环境中的无实验
	<ol>
		<li>在仪器科学家的协助下, 确保样品阶段附有所需的温度控制, 能够从 70-20 ° c 指示温度斜坡。</li>
		<li>将班卓琴细胞放在适当大小的固定块、安全和标签上。</li>
		<li>用0.1 毫米厚的铝箔包装整个块, 以确保没有环境光是事件的样品。最小化箔的变形, 以确保在样品阶段适当地贴合被包装的块。将此包装块和样品放在样品阶段。</li>
		<li>在仪器科学家的协助下, 使用适当的标准测量完成适当的仪器对准和校准。将探测器距离设置为接近其最大设置 (例如, 在 18 m), 以确保访问最低 q 区域 (〜0.001 Å-1), 最终允许一个完整的 q 范围约 0.001-0. 1 Å-1。这将允许探测长度扩展到 ~ 500 nm。</li>
		<li>在仪器科学家的协助下, 收集 P3HT 和溶剂样品的计数率, 并进行计算, 以确定达到总探测器计数所需的散射时间, 每样本约50万至 100万, 确保数据的良好统计质量。</li>
		<li>有了这些信息, 创建了一个示例脚本, 它将指导70-20 ° c 温度斜坡和数据采集过程。选择一个离散温度点的范围, 最好在给定的时间限制内覆盖整个范围, 例如每2° c。对于坡道上的每一点, 在脚本中有3单独的条目: 对所需温度的变化, 一个等待周期 (〜15分钟), 使系统在散射之前热平衡, 散射测量本身进行适当的时间期限, 以达到所需的检测器计数</li>
		<li>一旦仪器和脚本准备就绪, 执行脚本并开始实验。一定要收集的溶剂和空电池的数据, 以及 (没有温度斜坡)。此外, 收集每个样本的传输数据和一个阻止光束测量。</li>
	</ol>
	</li>
	<li>"光" 环境中的 san 实验
	<ol>
		<li>完成 "黑暗" 实验后, 将样品从舞台移到安全的台式上, 并在观察辐射安全规程时取下所有铝箔。</li>
		<li>在取样阶段附近放置一个具有卤素光源的光学照明灯, 使引线有效地照亮与散射收集位置相关的阶段中的取样槽。</li>
		<li>使用校准的测光表, 记录光源在试样所处位置的最大强度所提供的光强。强度值会随着照明灯和样品阶段的配置而变化, 但是, 至少需要5000勒克斯的光照强度。</li>
		<li>一旦光照设置正确组装, 将样品返回到舞台, 确保照明灯正确地亮起活动样本, 再加热到70° c, 允许适当的平衡, 并重复在黑暗中执行的数据收集程序样品, 与光学照明灯提供不间断的直接光曝光彻底的整个持续的这一步。</li>
	</ol>
	</li>
	<li>USANS 实验
	<ol>
		<li>使用石英班卓琴细胞和在温度控制的样品阶段的铜或钛块中放置类似的方式制备 USANS 样品。</li>
		<li>在仪器科学家的帮助下, 对准并校准在给定的中子波长上使用必要数量的缓冲器的仪器, 允许从大约 10-5 -10-3 Å-1中分析 Q 值, 允许长度在要探测的微米级上缩放。</li>
		<li>开发类似于 san 实验的实验脚本, 允许在以前研究的每个温度下进行热平衡和数据收集。</li>
		<li>再次复制 san 实验, 在 "黑暗" 条件下执行脚本一次, 然后在 "" "光照" 条件下再次运行。</li>
	</ol>
	</li>
</ol>
3。数据减少和分析
<ol>
	<li>san 减少和分析
	<ol>
		<li>使用相应的还原程序,32输入用于散射、背景 (溶剂)、空单元、阻塞光束和传输测量的数据文件, 以完成适当的背景减法和将散射数据转换为绝对在 cm-1中的强度单位。</li>
		<li>随着数据的适当减少, 开始分析通过拟合实验散射数据的模型, 这是线性加法的两个拟合方程, 一个代表 nanofibril 骨料通过椭圆形的圆筒模型,33和另一个考虑到自由链的解决方案通过聚合物排除体积模型。34,35下面的等式描述了这种组合模型方法: 
		<img alt="Equation 1" src="/files/ftp_upload/56163/56163eq1.jpg"> 在这个等式中, ϕP3HT描述了解决方案中 P3HT 的总体积分数, 是聚合 P3HT 的体积分数, 它是一个椭圆圆柱体, <img alt="Equation 2" src="/files/ftp_upload/56163/56163eq2.jpg"> PPEV 是自由链排除的卷表单系数为 P3HT, PECM 描述了聚合体的椭圆柱形系数, 而和是 P3HT 集料与溶剂之间的散射长度密度 () 和自由<img alt="Equation 3" src="/files/ftp_upload/56163/56163eq3.jpg"> <img alt="Equation 4" src="/files/ftp_upload/56163/56163eq4.jpg">P3HT 链和溶剂, 分别。对于系统的所有组件, 都可以通过对其化学成分和质量密度的了解, 以及使用可作为大多数中子分析程序或在线的一部分的可利用的一台计算机来计算。36</li>
		<li>在适当的拟合程序使用 NCNR 伊戈尔拟合宏37或 SASView 拟合程序, 获得的关键结构参数的胶凝系统在所有的温度在光明和黑暗的价值, 允许量化在整个过程中, 形态进化是温度和光照的函数。这些结构参数包括 nanofibrils 的横截面积、自由链回转半径 (Rg) 和 Porod 指数, 以及对 nanofibril 阶段中存在的材料总量的定性评估。</li>
	</ol>
	</li>
	<li>USANS 还原与分析
	<ol>
		<li>使用相应的缩减程序, 输入每个缓冲区的散射数据和背景数据, 将数据合并为 cm-1的绝对强度单位中的单个缩减曲线。</li>
		<li>使用吉尼尔-Porod 幂定律模型对数据进行分析, 允许对 USANS 长度尺度探测到的聚合散射模式进行定量评估, 并允许获取聚合 Rg值。38适合使用此方法通过 NCNR 伊戈尔拟合宏37或 SASView 管接头程序, 以便在所有温度和光照条件下比较宏聚合 Rg 。</li>
	</ol>
	</li>
</ol>

<ol>
	<li>G&#252;nes, S., Neugebauer, H., Sariciftci, N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conjugated+Polymer-Based+Organic+Solar+Cells.">Conjugated Polymer-Based Organic Solar Cells.</a> Chem. Rev. 107 (4), 1324-1338 (2007).</li><li>Burroughes, J. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-Emitting+Diodes+Based+on+Conjugated+Polymers.">Light-Emitting Diodes Based on Conjugated Polymers.</a> Letters to Nature. 347, 539-541 (1990).</li><li>Coakley, K. M., McGehee, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conjugated+Polymer+Photovoltaic+Cells.">Conjugated Polymer Photovoltaic Cells.</a> Chem. Mater. 16 (23), 4533-4542 (2004).</li><li>Tyler McQuade, D., Pullen, A. E., Swager, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conjugated+Polymer-Based+Chemical+Sensors.">Conjugated Polymer-Based Chemical Sensors.</a> Chem. Rev. 100 (7), 2537-2574 (2000).</li><li>Wang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-Stratified+Semiconductor/dielectric+Polymer+Blends:+Vertical+Phase+Separation+for+Facile+Fabrication+of+Organic+Transistors.">Self-Stratified Semiconductor/dielectric Polymer Blends: Vertical Phase Separation for Facile Fabrication of Organic Transistors.</a> J. Mater. Chem. C. 1 (25), 3989 (2013).</li><li>Segalman, R., McCulloch, B., Kirmayer, S., Urban, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Block+Copolymers+for+Organic+Optoelectronics.">Block Copolymers for Organic Optoelectronics.</a> Macromolecules. 42 (23), 9205-9216 (2009).</li><li>Chen, H., Hsiao, Y., Hu, B., Dadmun, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Control+of+Morphology+and+Function+of+Low+Band+Gap+Polymer-bis-Fullerene+Mixed+Heterojunctions+in+Organic+Photovoltaics+with+Selective+Solvent+Vapor+Annealing.">Control of Morphology and Function of Low Band Gap Polymer-bis-Fullerene Mixed Heterojunctions in Organic Photovoltaics with Selective Solvent Vapor Annealing.</a> J. Mater. Chem. A. 2, 9883 (2014).</li><li>Li, Y., Vamvounis, G., Holdcroft, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuning+Optical+Properties+and+Enhancing+Solid-State+Emission+of+Poly+(Thiophene)+S+by+Molecular+Control:+A+Postfunctionalization+Approach.">Tuning Optical Properties and Enhancing Solid-State Emission of Poly (Thiophene) S by Molecular Control: A Postfunctionalization Approach.</a> Macromolecules. 35, 6900-6906 (2002).</li><li>Nguyen, T. -. Q., Martini, I. B., Liu, J., Schwartz, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlling+Interchain+Interactions+in+Conjugated+Polymers:+The+Effects+of+Chain+Morphology+on+Exciton&#8722;,Exciton+Annihilation+and+Aggregation+in+MEH&#8722;,PPV+Films.">Controlling Interchain Interactions in Conjugated Polymers: The Effects of Chain Morphology on Exciton&#8722;,Exciton Annihilation and Aggregation in MEH&#8722;,PPV Films.</a> J. Phys. Chem. B. 104 (2), 237-255 (2000).</li><li>Chen, H., Hu, S., Zang, H., Hu, B., Dadmun, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Precise+Structural+Development+and+Its+Correlation+to+Function+in+Conjugated+Polymer:+Fullerene+Thin+Films+by+Controlled+Solvent+Annealing.">Precise Structural Development and Its Correlation to Function in Conjugated Polymer: Fullerene Thin Films by Controlled Solvent Annealing.</a> Adv. Funct. Mater. 23, 1701-1710 (2013).</li><li>Schwartz, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conjugated+Polymers+as+Molecular+Materials:+How+Chain+Conformation+and+Film+Morphology+Influence+Energy+Transfer+and+Interchain+Interactions.">Conjugated Polymers as Molecular Materials: How Chain Conformation and Film Morphology Influence Energy Transfer and Interchain Interactions.</a> Annu. Rev. Phys. Chem. 54 (3), 141-172 (2003).</li><li>Haugeneder, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exciton+Diffusion+and+Dissociation+in+Conjugated+Polymer/fullerene+Blends+and+Heterostructures.">Exciton Diffusion and Dissociation in Conjugated Polymer/fullerene Blends and Heterostructures.</a> Phys. Rev. B. 59 (23), 15346-15351 (1999).</li><li>Sirringhaus, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Two-Dimensional+Charge+Transport+in+Self-Organized,+High-Mobility+Conjugated+Polymers.">Two-Dimensional Charge Transport in Self-Organized, High-Mobility Conjugated Polymers.</a> Nature. 401 (6754), 685-688 (1999).</li><li>Al-Ibrahim, M., Ambacher, O., Sensfuss, S., Gobsch, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+Solvent+and+Annealing+on+the+Improved+Performance+of+Solar+Cells+Based+on+poly(3-Hexylthiophene):+Fullerene.">Effects of Solvent and Annealing on the Improved Performance of Solar Cells Based on poly(3-Hexylthiophene): Fullerene.</a> Appl. Phys. Lett. 86, 201120 (2005).</li><li>Koppe, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Influence+of+Molecular+Weight+Distribution+on+the+Gelation+of+P3HT+and+Its+Impact+on+the+Photovoltaic+Performance.">Influence of Molecular Weight Distribution on the Gelation of P3HT and Its Impact on the Photovoltaic Performance.</a> Macromolecules. 42, 4661-4666 (2009).</li><li>Malik, S., Jana, T., Nandi, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermoreversible+Gelation+of+Regioregular+poly(3-Hexylthiophene)+in+Xylene.">Thermoreversible Gelation of Regioregular poly(3-Hexylthiophene) in Xylene.</a> Macromolecules. 34 (2), 275-282 (2001).</li><li>Xu, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sol–gel+Transition+of+poly(3-Hexylthiophene)+Revealed+by+Capillary+Measurements:+Phase+Behaviors,+Gelation+Kinetics+and+the+Formation+Mechanism.">Sol–gel Transition of poly(3-Hexylthiophene) Revealed by Capillary Measurements: Phase Behaviors, Gelation Kinetics and the Formation Mechanism.</a> Soft Matter. 8, 726 (2012).</li><li>Chan, K. H. K., Yamao, T., Kotaki, M., Hotta, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unique+Structural+Features+and+Electrical+Properties+of+Electrospun+Conjugated+Polymer+poly(3-Hexylthiophene)+(P3HT)+Fibers.">Unique Structural Features and Electrical Properties of Electrospun Conjugated Polymer poly(3-Hexylthiophene) (P3HT) Fibers.</a> Synth. Met. 160 (23-24), 2587-2595 (2010).</li><li>Wicklein, A., Ghosh, S., Sommer, M., W&#252;rthner, F., Thelakkat, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Self-Assembly+of+Semiconductor+Organogelator+Nanowires+for+Photoinduced+Charge+Separation.">Self-Assembly of Semiconductor Organogelator Nanowires for Photoinduced Charge Separation.</a> ACS Nano. 3 (5), 1107-1114 (2009).</li><li>Newbloom, G. M., Weigandt, K. M., Pozzo, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrical,+Mechanical,+and+Structural+Characterization+of+Self-Assembly+in+poly(3-Hexylthiophene)+Organogel+Networks.">Electrical, Mechanical, and Structural Characterization of Self-Assembly in poly(3-Hexylthiophene) Organogel Networks.</a> Macromolecules. 45, 3452-3462 (2012).</li><li>Li, L., Tang, H., Wu, H., Lu, G., Yang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+Fullerene+Solubility+on+the+Crystallization+of+poly(3-Hexylthiophene)+and+Performance+of+Photovoltaic+Devices.">Effects of Fullerene Solubility on the Crystallization of poly(3-Hexylthiophene) and Performance of Photovoltaic Devices.</a> Org. Electron. physics, Mater. Appl. 10 (7), 1334-1344 (2009).</li><li>Bu, L., Pentzer, E., Bokel, F. A., Emrick, T., Hayward, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+of+Polythiophene+/+Perylene+Tetracarboxydiimide+Donor+/+Acceptor+Shish-Kebab+Nanostructures+by+Coupled+Crystal+Modi+Fi+Cation.">Growth of Polythiophene / Perylene Tetracarboxydiimide Donor / Acceptor Shish-Kebab Nanostructures by Coupled Crystal Modi Fi Cation.</a> ACS Nano. 6 (12), 10924-10929 (2012).</li><li>Yang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoscale+Morphology+of+High-Performance+Polymer+Solar+Cells.">Nanoscale Morphology of High-Performance Polymer Solar Cells.</a> Nano Lett. 5 (4), 579-583 (2005).</li><li>Newbloom, G. M., Kim, F. S., Jenekhe, S. a., Pozzo, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesoscale+Morphology+and+Charge+Transport+in+Colloidal+Networks+of+Poly(3-Hexylthiophene).">Mesoscale Morphology and Charge Transport in Colloidal Networks of Poly(3-Hexylthiophene).</a> Macromolecules. 44, 3801-3809 (2011).</li><li>Tretiak, S., Saxena, A., Martin, R., Bishop, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conformational+Dynamics+of+Photoexcited+Conjugated+Molecules.">Conformational Dynamics of Photoexcited Conjugated Molecules.</a> Phys. Rev. Lett. 89 (9), 97402 (2002).</li><li>Botiz, I., Freyberg, P., Stingelin, N., Yang, A. C. -. M., Reiter, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversibly+Slowing+Dewetting+of+Conjugated+Polymers+by+Light.">Reversibly Slowing Dewetting of Conjugated Polymers by Light.</a> Macromolecules. 46, 2352-2356 (2013).</li><li>Botiz, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancing+the+Photoluminescence+Emission+of+Conjugated+MEH-PPV+by+Light+Processing.">Enhancing the Photoluminescence Emission of Conjugated MEH-PPV by Light Processing.</a> ACS Appl. Mater. Interfaces. 6 (7), 4974-4979 (2014).</li><li>Morgan, B., Dadmun, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Illumination+Alters+the+Structure+of+Gels+Formed+from+the+Optoelectronic+Material+P3HT.">Illumination Alters the Structure of Gels Formed from the Optoelectronic Material P3HT.</a> Polymer. 108, 313-321 (2017).</li><li>Morgan, B., Dadmun, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Illumination+of+Conjugated+Polymer+in+Solution+Alters+Its+Conformation+and+Thermodynamics.">Illumination of Conjugated Polymer in Solution Alters Its Conformation and Thermodynamics.</a> Macromolecules. 49 (9), 3490-3496 (2016).</li><li>Ilavsk, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phase+Transition+in+Swollen+Gels.+2.+Effect+of+Charge+Concentration+on+the+Collapse+and+Mechanical+Behavior+of+Polyacrylamide+Networks.">Phase Transition in Swollen Gels. 2. Effect of Charge Concentration on the Collapse and Mechanical Behavior of Polyacrylamide Networks.</a> Macromolecules. 15, 782-788 (1982).</li><li>Tanaka, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collapse+of+Gels+and+the+Critical+Endpoint.">Collapse of Gels and the Critical Endpoint.</a> Phys. Rev. Lett. 40 (12), 820-823 (1978).</li><li>. SANS &amp; USANS Data Reduction and Analysis Available from: <a target="_blank" href="https://www.ncnr.nist.gov/programs/sans/data/red_anal.html">https://www.ncnr.nist.gov/programs/sans/data/red_anal.html</a> (2017)</li><li>Feigin, L., Svergun, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Structure Analysis by Small-Angle X-Ray and Neutron Scattering. , (1987).</li><li>Mittelbach, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Zur+Rontgenkleinwinkelstreuung+verdunnter+kolloider+systeme.">Zur Rontgenkleinwinkelstreuung verdunnter kolloider systeme.</a> Acta Phys. Austriaca. 14, 185-211 (1961).</li><li>Schulz, G. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#220;ber+die+Kinetik+der+Kettenpolymerisationen.">&#220;ber die Kinetik der Kettenpolymerisationen.</a> Z. Phys. Chem. 43, 25 (1935).</li><li>. Neutron activation and scattering calculator Available from: <a target="_blank" href="https://www.ncnr.nist.gov/resources/activation">https://www.ncnr.nist.gov/resources/activation</a> (2017)</li><li>Kline, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+and+Analysis+of+SANS+and+USANS+Data+Using+IGOR+Pro.">Reduction and Analysis of SANS and USANS Data Using IGOR Pro.</a> J. Appl. Crystallogr. 39 (6), 895-900 (2006).</li><li>Guinier, A., Fournet, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Small-Angle Scattering of X-Rays. , (1955).</li></ol>

作者没有什么可透露的。

首先, 将 san 数据看作是温度的函数, 在椭圆柱模型的比例因子的增加表明, nanofibril 相中的 P3HT 量有明显的增加, 这与凝胶过程的进展 isconsistent.同时, 自由链 Rg的减少与 Porod 指数的增加相匹配, 表明随着温度的降低, 热力学条件的恶化导致了 P3HT 链中仍然存在的链坍塌解决.这些结果, 结合 USANS 数据显示 macroaggregate Rg在温度下降时的显著增加, 表明散射实验有效地捕获和分析了结构自...

共轭聚合物承诺功能材料, 可用于广泛的设备, 如有机发光二极管, 有机半导体, 化学传感器, 有机光伏。1,2,3,4,5,6在这些设备中, 性能的一个重要方面是在活动层中的固态共轭聚合物的有序和包装。7,8,9,10,11,12,13,14这种形态主要是由溶液中的聚合物链的构象以及随着这些溶液被浇铸到基材和溶剂被去除而演化的结构所预先确定的。通过研究在一个合适的溶剂中的模型光电聚合物的典型溶胶-凝胶过渡的结构, 这些系统可以有效地建模, 并对材料沉积过程中发生的自组装进行定量的一瞥。可以获得。15,16,17,18,19,20
具体来说, 我们研究的共轭聚合物基准 P3HT 在溶剂氘邻二氯苯 (管理局), 一个高分子溶剂系统, 已广泛使用, 因为它适合各种有机电子器件制造技术.23,24,25在给定的溶剂环境中, P3HT 链开始聚集在适当的环境刺激上, 如温度降低或溶剂质量损失。这一装配过程的确切机制正在调查中, 其中一个主要的建议路径被认为是一个渐进的过程, 其中单个 P3HT 分子π堆叠形成层状纳米聚集体称为 nanofibrils, 然后他们自己凝聚形成更大的微米级宏观集料。24了解这些通路, 形成的结构是正确预测和影响最佳器件活性层形态形成的关键。
针对这一最终目标, 更精确地指导这些主动层结构的形成, 有需要开发额外的实验和工业方法, 无损改变共轭聚合物形态原位。一个相对较新的方法中心围绕使用光曝光作为一种廉价的手段来改变聚合物链的形态, 同时计算和实验结果都指向它的可行性。25,26,27我们的实验室最近的工作表明, 在稀释溶液中存在着对光诱导的共轭聚合物-溶剂相互作用的改变, 从而导致聚合物链尺寸在光照时发生显著变化。30,31在这里, 我们提出了一个协议来继续这项工作, 通过有效地监测暴露一个更集中的共轭聚合物溶液的影响, 直接光整个凝胶过程, 是由恒温控制的指示温度斜坡我们使用中子散射, 因为它允许对聚合物-溶剂溶胶-凝胶系统的结构参数进行稳健的分析, 从埃到微米, 这种能力不可能通过其他更常见的流变或光谱学工具方法.16,17,30,31因此, 通过比较正确分析的小和超小型角中子数据, 将在光照下形成的凝胶组装成完全黑暗中收集的相同数据, 由光照驱动引起的结构差异可以全面确定和量化效果。

<table><tbody><tr><td>M(106) poly(3-hexylthiophene-2,5-diyl) (P3HT)</td><td>Ossila</td><td>104934-50-1</td><td>Conjugated polymer</td></tr><tr><td>deuterated 1,2 ortho-dichlorobenzene (ODCB)</td><td>Sigma Aldrich</td><td>AC321260050</td><td>solvent</td></tr></tbody></table>

monitoring the effects of illumination on the structure of conjugated polymer gels using neutron scattering

我们演示了一个协议, 以有效地监测高浓度的共轭聚合物溶液在存在和没有白光照射的凝胶过程。通过建立一个受控的温度斜坡, 这些材料的凝胶可以精确地监测, 因为它们进行这种结构演变, 有效地反映了在有机电子设备制造。利用小角中子散射 (san) 和超小型角中子散射 (USANS) 以及适当的拟合协议, 我们对整个过程中选择结构参数的演化进行了量化。透彻的分析表明, 在整个凝胶过程中持续的光暴露会显著改变最终形成的凝胶的结构。具体来说, 聚 (3-吩-25-酚) (P3HT) 纳米级集料的聚合过程受到光照的影响, 最终导致共轭高分子微结构的生长迟缓和形成小规模的宏观聚集群。

通过 san 和 USANS 实验, 对 d-管理局中 P3HT 的凝胶过程进行了有效的监测, 从70° c 的分散溶液状态到20° c 时的完全胶体状态。这些实验都是在完全黑暗和白光光照下进行的。图 1显示了从这些实验中减去数据曲线的一些示例, 并在图 2中显示了一个示例曲线拟合。从这一数据中, 随着温度的下降, 由于绝对强度的明显增加, 结构的变?...

Watch this Scientific Journal Video about Monitoring the Effects of Illumination on the Structure of Conjugated Polymer Gels Using Neutron Scattering at JoVE.com

Monitoring the Effects of Illumination on the Structure of Conjugated Polymer Gels Using Neutron Scattering

本文提出了一种由光电共轭聚合物聚 (3-吩-25-酚) (P3HT) 组成的凝胶的分析方法, 利用小超小型角中子散射在光照的存在和缺乏的情况下进行。

利用中子散射监测光照对共轭高分子凝胶结构的影响

We demonstrate a protocol to effectively monitor the gelation process of a high concentration solution of conjugated polymer both in the presence and ...

monitoring-effects-illumination-on-structure-conjugated-polymer-gels

Universidad San Sebastian

Research

JoVE Journal

Chemistry

5.7K 次观看.  University of Tennessee, Knoxville. 本文提出了一种由光电共轭聚合物聚 (3-吩-25-酚) (P3HT) 组成的凝胶的分析方法, 利用小超小型角中子散射在光照的存在和缺乏的情况下进行。

视频: Monitoring the Effects of Illumination on the Structure of Conjugated Polymer Gels Using Neutron Scattering

Using Neutron Spin Echo Resolved Grazing Incidence Scattering to Investigate Organic Solar Cell Materials

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped crystallites. Neutrons are passed through two well defined regions of magnetic field; one before and one after the sample. The two magnetic field regions have opposite polarity and are tuned such that neutrons travelling through both regions, without being perturbed, will undergo the same number of precessions in opposing directions. In this case the neutron precession in the second arm is said to &#34;echo&#34; the first, and the original polarization of the beam is preserved. If the neutron interacts with a sample and scatters elastically the path through the second arm is not the same as the first and the original polarization is not recovered. Depolarization of the neutron beam is a highly sensitive probe at very small angles (&#60;50&#160;&#956;rad) but still allows a high intensity, divergent beam to be used. The decrease in polarization of the beam reflected from the sample as compared to that from the reference sample can be directly related to structure within the sample.
In comparison to scattering observed in neutron reflection measurements the SERGIS signals are often weak and are unlikely to be observed if the in-plane structures within the sample under investigation are dilute, disordered, small in size and polydisperse or the neutron scattering contrast is low. Therefore, good results will most likely be obtained using the SERGIS technique if the sample being measured consist of thin films on a flat substrate and contain scattering features that contains a high density of moderately sized features (30 nm to 5 &#181;m) which scatter neutrons strongly or the features are arranged on a lattice. An advantage of the SERGIS technique is that it can probe structures in the plane of the sample.

Progress has been made in utilizing spin echo resolved grazing incidence scattering (SERGIS) as a neutron scattering technique to probe the length-scales in irregular samples. Crystallites of [6,6]-phenyl-C61-butyric acid methyl ester have been probed using the SERGIS technique and the results confirmed by optical and atomic force microscopy.

使用中子自旋回声解决放牧发生率散射调查有机太阳能电池材料

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped ...

科研

工程学

Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus have potential applications in nonlinear optics, which requires extraordinary optical intensity. One of the most studied nonlinearities in plasmonics is nonlinear absorption, including saturation and reverse saturation behaviors. Although scattering and absorption in nanoparticles are closely correlated by the Mie theory, there has been no report of nonlinearities in plasmonic scattering until very recently. 
Last year, not only saturation, but also reverse saturation of scattering in an isolated plasmonic particle was demonstrated for the first time. The results showed that saturable scattering exhibits clear wavelength dependence, which seems to be directly linked to the localized surface plasmon resonance (LSPR). Combined with the intensity-dependent measurements, the results suggest the possibility of a common mechanism underlying the nonlinear behaviors of scattering and absorption. These nonlinearities of scattering from a single gold nanosphere (GNS) are widely applicable, including in super-resolution microscopy and optical switches. 
In this paper, it is described in detail how to measure nonlinearity of scattering in a single GNP and how to employ the super-resolution technique to enhance the optical imaging resolution based on saturable scattering. This discovery features the first super-resolution microscopy based on nonlinear scattering, which is a novel non-bleaching contrast method that can achieve a resolution as low as l/8 and will potentially be useful in biomedicine and material studies.

Saturable and reverse saturable scattering were discovered in isolated plasmonic particles and adopted as a novel non-bleaching contrast method in super-resolution microscopy. Here the experimental procedures of detecting and extracting nonlinear scattering are explained in detail, as well as how to enhance resolution with the aid of saturated excitation microscopy.

从单电浆纳米粒子散射非线性测量

Plasmonics, which are based on the collective oscillation of electrons due to light excitation, involve strongly enhanced local electric fields and thus ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

超分子胶体的合成与表征

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

化学

Controlled Synthesis and Fluorescence Tracking of Highly Uniform Poly(N-isopropylacrylamide) Microgels

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this work, we use single particle tracking of fluorescently labeled PNIPAM microgels as a showcase for tuning microgel size by a rapid non-stirred precipitation polymerization procedure. This approach is well suited for prototyping new reaction compositions and conditions or for applications that do not require large amounts of product. Microgel synthesis, particle size and structure determination by dynamic and static light scattering are detailed in the protocol. It is shown that the addition of functional comonomers can have a large influence on the particle nucleation and structure. Single particle tracking by wide-field fluorescence microscopy allows for an investigation of the diffusion of labeled tracer microgels in a concentrated matrix of non-labeled microgels, a system not easily investigated by other methods such as dynamic light scattering.

Controlled Synthesis and Fluorescence Tracking of Highly Uniform PolyN-isopropylacrylamide Microgels

Non-stirred precipitation polymerization provides a rapid, reproducible prototyping approach to the synthesis of stimuli-sensitive poly(N-isopropylacrylamide) microgels of narrow size distribution. In this protocol synthesis, light scattering characterization and single particle fluorescence tracking of these microgels in a wide-field microscopy setup are demonstrated.

可控合成和高度统一聚荧光追踪（<em&gt;ñ</em&gt; -isopropylacrylamide）微凝胶

Stimuli-sensitive poly(N-isopropylacrylamide) (PNIPAM) microgels have various prospective practical applications and uses in fundamental research. In this ...

Advanced Compositional Analysis of Nanoparticle-polymer Composites Using Direct Fluorescence Imaging

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise composition of these materials is essential, especially in the design of surface catalysts, where the surface concentration of the active component determines the activity of the material. Antimicrobial materials which utilize nanoparticles are a particular focus of this technology. Recently swell encapsulation has emerged as a technique for inserting antimicrobial nanoparticles into a host polymer matrix. Swell encapsulation provides the advantage of localizing the incorporation to the external surfaces of materials, which act as the active sites of these materials. However, quantification of this nanoparticle uptake is challenging. Previous studies explore the link between antimicrobial activity and surface concentration of the active component, but this is not directly visualized. Here we show a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of CdSe/ZnS nanoparticles can be accurately visualized through cross-sectional fluorescence imaging. Using this method, we can quantify the uptake of nanoparticles via swell encapsulation and measure the surface concentration of encapsulated particles, which is key in optimizing the activity of functional materials.

Here we present a reliable method to monitor the incorporation of nanoparticles into a polymer host matrix via swell encapsulation. We show that the surface concentration of cadmium selenide quantum dots can be accurately visualized through cross-sectional fluorescence imaging.

纳米粒子 - 聚合物复合材料使用直接荧光成像的先进成分分析

The fabrication of polymer-nanoparticle composites is extremely important in the development of many functional materials. Identifying the precise ...

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a technique used to measure the size distribution of polymer solutions or colloidal particles. Although this technique is widely used for the assessment of polymer solutions, it is difficult to measure the particle size in concentrated solutions due to the multiple scattering effect or strong light absorption. Therefore, the concentrated solutions should be diluted before measurement. Implementation of the confocal optical component in a dynamic light scattering microscope1 helps to overcome this barrier. Using such a microscopic system, both transparent and turbid systems can be analyzed under the same experimental setup without a dilution. As a representative example, a size distribution measurement of a temperature-responsive polymer solution was performed. The sizes of the polymer chains in an aqueous solution were several tens of nanometers at a temperature below the lower critical solution temperature (LCST). In contrast, the sizes increased to more than 1.0 &#181;m when above the LCST. This result is consistent with the observation that the solution turned turbid above the LCST.

A protocol for the direct measurement of particle size distribution in concentrated solutions using dynamic light scattering microscopy is presented.

通过动态光散射显微镜混浊解决方案粒度分布的测定

A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a ...

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational spectroscopy and time-resolved electron diffraction. Liquid crystal phase is an important state of matter that exists between the solid and liquid phases and it is common in natural systems as well as in organic electronics. Liquid crystals are orientationally ordered but loosely packed, and therefore, the internal conformations and alignments of the molecular components of LCs can be modified by external stimuli. Although advanced time-resolved diffraction techniques have revealed picosecond-scale molecular dynamics of single crystals and polycrystals, direct observations of packing structures and ultrafast dynamics of soft materials have been hampered by blurry diffraction patterns. Here, we report time-resolved IR vibrational spectroscopy and electron diffractometry to acquire ultrafast snapshots of a columnar LC material bearing a photoactive core moiety. Differential-detection analyses of the combination of time-resolved IR vibrational spectroscopy and electron diffraction are powerful tools for characterizing structures and photoinduced dynamics of soft materials.

Here, we present the protocols of differential-detection analyses of time-resolved infrared vibrational spectroscopy and electron diffraction which enable observations of the deformations of local structures around photoexcited molecules in a columnar liquid crystal, giving an atomic perspective on the relationship between the structure and the dynamics of this photoactive material.

观测 Photoresponsive 液晶结构动力学的新方法

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational ...

Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes and determine the corresponding photochemical mechanism. Then, we describe a protocol to perform ring-opening metathesis polymerization (ROMP) in solution and in miniemulsion using this NHC-photogenerating system. To photogenerate IMes, a system comprising 2-isopropylthioxanthone (ITX) as the sensitizer and 1,3-dimesitylimidazolium tetraphenylborate (IMesH+BPh4-) as the protected form of NHC is employed. IMesH+BPh4- can be obtained in a single step by anion exchange between 1,3-dimesitylimidazolium chloride and sodium tetraphenylborate. A real-time steady-state photolysis setup is described, which hints that the photochemical reaction proceeds in two consecutive steps: 1) ITX triplet is photo-reduced by the borate anion and 2) subsequent proton transfer takes place from the imidazolium cation to produce the expected NHC IMes. Two separate characterization protocols are implemented. Firstly, CS2 is added to the reaction media to evidence the photogeneration of NHC through formation of the IMes-CS2 adduct. Secondly, the amount of NHC released in situ is quantified using acid-base titration. The use of this NHC photo-generating system for the ROMP of norbornene is also discussed. In solution, a photopolymerization experiment is conducted by mixing ITX, IMesH+BPh4-, [RuCl2(p-cymene)]2 and norbornene in CH2Cl2, then irradiating the solution in a UV reactor. In a dispersed medium, a monomer miniemulsion is first formed then irradiated inside an annular reactor to produce a stable poly(norbornene) latex.

We describe a protocol to photogenerate N-heterocyclic carbenes (NHCs) by UV irradiation of a 2-isopropylthioxanthone/imidazolium tetraphenylborate salt system. Methods to characterize the photoreleased NHC and elucidate the photochemical mechanism are proposed. The protocols for ring-opening metathesis photopolymerization in solution and miniemulsion illustrate the potential of this 2-component NHC photogenerating system.

n-杂环卡本的光生成在光致环开环转移聚合中的应用

We report a method to generate the N-heterocyclic carbene (NHC) 1,3-dimesitylimidazol-2-ylidene (IMes) under UV-irradiation at 365 nm to characterize IMes ...

Light-mediated Formation and Patterning of Hydrogels for Cell Culture Applications

Click chemistries have been investigated for use in numerous biomaterials applications, including drug delivery, tissue engineering, and cell culture. In particular, light-mediated click reactions, such as photoinitiated thiol&#8722;ene and thiol&#8722;yne reactions, afford spatiotemporal control over material properties and allow the design of systems with a high degree of user-directed property control. Fabrication and modification of hydrogel-based biomaterials using the precision afforded by light and the versatility offered by these thiol&#8722;X photoclick chemistries are of growing interest, particularly for the culture of cells within well-defined, biomimetic microenvironments. Here, we describe methods for the photoencapsulation of cells and subsequent photopatterning of biochemical cues within hydrogel matrices using versatile and modular building blocks polymerized by a thiol&#8722;ene photoclick reaction. Specifically, an approach is presented for constructing hydrogels from allyloxycarbonyl (Alloc)-functionalized peptide crosslinks and pendant peptide moieties and thiol-functionalized poly(ethylene glycol) (PEG) that rapidly polymerize in the presence of lithium acylphosphinate photoinitiator and cytocompatible doses of long wavelength ultraviolet (UV) light. Facile techniques to visualize photopatterning and quantify the concentration of peptides added are described. Additionally, methods are established for encapsulating cells, specifically human mesenchymal stem cells, and determining their viability and activity. While the formation and initial patterning of thiol-alloc hydrogels are shown here, these techniques broadly may be applied to a number of other light and radical-initiated material systems (e.g., thiol-norbornene, thiol-acrylate) to generate patterned substrates.

We describe a sequential process for light-mediated formation and subsequent biochemical patterning of synthetic hydrogel matrices for three-dimensional cell culture applications. The construction and modification of hydrogels with cytocompatible photoclick chemistry is demonstrated. Additionally, facile techniques to quantify and observe patterns and determine cell viability within these hydrogels are presented.

用于细胞培养应用光介导的形成和构图的水凝胶

Click chemistries have been investigated for use in numerous biomaterials applications, including drug delivery, tissue engineering, and cell culture. In ...

生物工程

Neutron Crystallography Data Collection and Processing for Modelling Hydrogen Atoms in Protein Structures

Neutron crystallography is a structural technique that allows determination of hydrogen atom positions within biological macromolecules, yielding mechanistically important information about protonation and hydration states while not inducing radiation damage. X-ray diffraction, in contrast, provides only limited information on the position of light atoms and the X-ray beam&#160;rapidly induces radiation damage of photosensitive&#160;cofactors and metal centers. Presented here is the workflow employed for the IMAGINE and MaNDi beamlines at Oak Ridge National Laboratory (ORNL) to obtain a neutron diffraction structure once a protein crystal of suitable size (&#62; 0.1 mm3) has been grown. We demonstrate mounting of hydrogenated protein&#160;crystals in quartz capillaries for neutron diffraction data collection. Also presented is the vapor exchange process of the mounted crystals with D2O-containing buffer to ensure replacement of hydrogen atoms at exchangeable sites with deuterium. The incorporation of deuterium reduces the background arising from the incoherent scattering of hydrogen atoms and prevents density cancellation caused by their negative coherent scattering length. Sample alignment and room temperature data collection strategies are illustrated using quasi-Laue data collection at IMAGINE at the High Flux Isotope Reactor (HFIR). Furthermore, crystal mounting and rapid freezing in liquid nitrogen for cryo-data collection to trap labile reaction intermediates is demonstrated at the MaNDi time-of-flight instrument at the Spallation Neutron Source (SNS). Preparation of the model coordinate and diffraction data files and visualization of the neutron scattering length density (SLD) maps will also be addressed. Structure refinement against neutron data-only or against joint X-ray/neutron data to obtain an all-atom structure of the protein of interest will finally be discussed. The process of determining a neutron structure will be demonstrated using crystals of the lytic polysaccharide monooxygenase Neurospora crassa LPMO9D, a copper-containing metalloprotein involved in the degradation of recalcitrant polysaccharides via oxidative cleavage of the glycosidic bond.

Neutron protein crystallography is a structural technique that permits the localization of hydrogen atoms, thereby providing important mechanistic details of protein function. We present here the workflow for mounting a protein crystal, neutron diffraction data collection, structure refinement and analysis of the neutron scattering length density maps.

利用中子散射监测光照对共轭高分子凝胶结构的影响

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