Name: preparation and friction force microscopy measurements of immiscible, opposing polymer brushes
Uploaded: 2014-12-24T14:00:00.000+00:00
Duration: 13 min 57 s
Description: Watch this Scientific Journal Video about Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes at JoVE.com

我们感谢M. Hempenius和E.贝内蒂的富有成果的讨论，Y.玉仔细检查了配方，M. Vlot的图1，C.帕德伯格和K.斯密特的形象设计的技术支持。 EK承认荷兰科学研究组织（NWO，TOP格兰特700.56.322，高分子纳米技术与刺激响应聚合物）的资金支持。深发展已经由基金会基础研究物质（FOM），这是经济由荷兰科学研究组织（NWO）支持支持。

注: 图2示出了样品制备过程。聚合物刷从硅接枝（Si）的衬底（路径（一）），来自金涂覆的基材（100纳米金蒸发在Si晶片具有10纳米的铬粘合层，路径（B）），并从金胶体AFM探针（6微米的直径，路径（C））通过表面引发原子转移自由基聚合（SI-ATRP）24。原子力显微镜测量在一多模AFM进行与低噪声头，垂直接合扫描仪和一个液体细胞。 1.样品制备<ol><li>基材的准备<ol><li>硅表面上引发剂沉积。 <ol><li>清洁硅衬底，用氯仿，然后食人鱼溶液，随后冲洗，用纯化水，乙醇，氯仿等。 </li><li>将干燥基质成围绕含有50微升（3-氨基丙基）三乙氧基硅烷的小瓶的干燥器。 </li><li>抽真空干燥器机智哈哈旋片泵15分钟，并关闭它之后。让气相沉积进行O / N。 </li><li>制备的40ml甲苯（脱气）和40μl三乙胺在锥形瓶中的溶液。 </li><li>放置衬底，在烧瓶中，并逐滴添加40微升的2-溴-2-甲基丙酰基。保持基板在该溶液中，以避免在溶液中形成盐晶体沉积。 </li><li>搅拌4小时，该溶液中。 </li><li>冲洗，用甲苯和乙醇的底物。接着，将基片放入聚合瓶中。 </li></ol></li><li>在金表面沉积引发<ol><li>制备单层溶液:溶解在20毫升2-溴-2-甲基 - 丙酸-11- [11-（2-溴-2-甲基丙酰氧基）-undecyldisulfanyl] -undecyl酯脱气氯仿（0.2毫摩尔）。 </li><li>转移约1.5毫升单层解决方案成小瓶以前用氩气冲洗。 </li><li>清洁金涂覆的基材，用氯仿和食人鱼的解决方案。随后冲洗用纯水，乙醇和氯仿。 </li><li>浸泡清洗过的衬底进单层溶液，并关闭该烧瓶。商店O / N在黑暗的地方。 </li><li>通过浸渍他们进入溶液清洁金胶体探针用乙醇和氯仿。 </li><li>浸入胶体探针到含有单层溶液的小瓶中。坚决关闭，并保持在一个黑暗的地方O / N。 </li><li>从溶液中取出基板，洗净，用氯仿和乙醇。接着，转移引发剂涂覆的基材到聚合瓶中。 </li><li>从单层溶液中除去胶体探针，洗净，用氯仿和乙醇。接下来，分别转让每个探头到聚合瓶中。 </li></ol></li></ol></li><li>聚合<ol><li> PMMA的SI-ATRP <ol><li>吹扫烧瓶和小瓶中，将含有引发剂覆盖的衬底（Si和金）和胶体探针Arg取代上30分钟。 </li><li>溶解10g甲基丙烯酸甲酯（MMA）的ATRP介质（10毫升甲醇/水混合物与比5:1）和脱气2小时的溶液中。 </li><li>加145毫克溴化亚铜和320毫克2,2-联吡啶到装有磁力搅拌棒的烧瓶中，并通过deoxygenize 3真空氩回填循环。 </li><li>转移脱气的单体溶液到烧瓶中（含有的铜），并搅拌另外15分钟，直到获得澄清的棕色溶液是观察。 </li><li>附加一个针到一个2毫升注射器和冲洗针和注射器用氩气2-3次。 </li><li>撤回与针筒1毫升聚合溶液，并注入该内容进入小反应瓶中，将含有胶体探针。 </li><li>撤回与注射器的剩余溶液，并注入该内容到反应小瓶中，将含有扁平衬底。补充足够的解决方案，完全淹没每个样品。 </li><li>进行聚合40小时，在RT。 </li><li>回复移动样品从聚合溶液和洗涤，用乙醇和氯仿在多个周期。样品的颜色表明刷子的存在。 </li><li>最后，干燥在氮气流中的衬底。 </li><li>保持在氮气箱平坦的基板。商店聚合物刷修饰探针的甲苯。 </li></ol></li><li> PNIPAM 10的SI-ATRP <ol><li>吹扫烧瓶和小瓶中，将含有引发剂覆盖的衬底（Si和金）和胶体探针用氩气30分钟。 </li><li>溶解5.6克ñ-isopropylacrylamide和320微升PMDETA在ATRP培养基（1.6毫升水中和18毫升甲醇）和脱气2小时的溶液中。 </li><li>添加76毫克溴化亚铜到装有磁力搅拌棒的烧瓶中，并通过3真空氩回填循环deoxygenize。 </li><li>转移脱气的单体溶液到包含铜烧瓶中。再搅拌15分钟，直到一个明确的解决方案，绿色观察。 </LI&gt; <li>附加一个针到一个2毫升注射器和冲洗针和注射器用氩气2-3次。 </li><li>撤回与针筒1毫升聚合溶液，并注入该内容进入小反应瓶中，将含有胶体探针。重复所有探头。 </li><li>撤回与注射器的剩余溶液，并注入该内容到反应烧瓶中，将含有扁平衬底。补充足够的解决方案，完全淹没每个样品。 </li><li>进行聚合2小时，在室温。 </li><li>从聚合溶液中除去样品并洗涤，通过多次循环乙醇和水。样品的出现颜色表示刷的存在。 </li><li>样本浸入0.1M的EDTA溶液，并保持它在溶液中O / N删除所有的铜。用纯化水和乙醇洗涤。 </li><li>保持在氮气箱的平坦的基板。存储PNIPAM刷修饰的探针在纯化水中。 </li></ol></li></ol></li><li>刷表征，傅立叶变换红外（ 图3） 注意:使用掠角FTIR模式对在Si衬底上聚合物刷金衬底和红外传输模式聚合物刷。仔细擦干所有样品。任何水和溶剂的污染可导致检测器的严重损坏。 <ol><li>根据由制造商提供的说明书启动设备。 </li><li>设置样品测量以下参数:900和3700厘米之间范围-1为4 -1和平均32次扫描在每次测量中的分辨率。 </li><li>根据用于样品制备协议清洁空白基板，仔细擦干，并将它放置到测量室。 </li><li>施加真空4小时。接下来，记录后台扫描。 </li><li>除去空白样品，并放置在样品室中的干聚合物刷涂覆的样品。 </li><li>在SAMPL应用真空Ë室和5小时录音采样扫描每30分钟。 </li><li>鉴定所有峰在光谱确认聚合物刷的化学组合物。 （只分析了直线基线的扫描。） </li></ol></li></ol> 2.测量AFM <ol><li>用针小心刮擦PMMA刷覆盖衬底，具有良好的溶剂冲洗以除去过量的聚合物和干燥。 </li><li>装载样品到AFM仪器安装探头插入液体池。 </li><li>在悬臂的端部的激光对准。 </li><li>与使用相机，对准上面的划痕一角。 </li><li>在接近和从事尖端，设置扫描尺寸0纳米。接着，接合尖端到表面。 </li><li>进入"斜坡模式"，并决定通过力距离曲线偏转灵敏度。校准使用"热调整"正常的弹簧常数作为软件和扭转弹簧常数Ø实现F使用Wagner 等人的方法在悬臂25 <ol><li>捕获在空气中的悬臂的扭转热噪声，使用在软件（6.25兆赫）的高速数据捕获持续2秒。 </li><li>热噪声转换成使用傅立叶变换的功率谱密度（V 2 / Hz）的。 </li><li>确定的基本共振和悬臂的使用中的功率谱密度的共振峰，并根据上面的公式简谐振荡器包括基线噪声（当量2价的25）的品质因数中的空气。 </li><li>计算使用悬臂的面内尺寸（长度和宽度），密度和周围介质（空气）的粘度和品质因数和共振频率使用萨德尔26的方法，在步骤2.6.3确定的扭转弹簧常数。 注:我们提供了用约翰·萨德的网站上的工具:www.ampc.ms.unimelb.edu.au/afm/calibration.html。 </li><li> CAlculate使用当量悬臂的扭转角偏转灵敏度。 6和参考文献7。 25。 </li><li>扭转弹簧常数和偏转灵敏度转换为使用胶体的大小，悬臂和当量的厚度的横向弹簧常数和偏转灵敏度。 8参考文献。 25。 注:探测器信号现在可以转换成经由力:力[N] =横向弹簧常数[牛顿/米] *横向偏转灵敏度[M / V] *检测器信号（V）。 </li></ol></li><li>通过成像刷子在一个划痕在尽可能低的设定值偏移测量干刷的刷高度。确定刷子的高度从所捕获的图像的线扫描。 </li><li>通过轻轻地把它应用到表面用注射器溶剂合物刷中苯乙酮。 注:样品的变化，因为溶剂蒸发的颜色。这允许对以下的干燥过程。 </li><li>安装样品的AFM。垂直的激光信号对齐-1.0 V.设置偏转设定为0 V，搞悬臂和表面。 注:使悬臂在与表面接触后，将苯乙酮移动到刷子上的胶体创建尖端与表面之间的毛细管桥梁。 </li><li>设置扫描尺寸至40μm，禁用慢扫描轴和设置图像纵横比为1:4。记录的高度和摩擦图像通道（包括迹线和回扫）。 </li><li>当图像被捕获撤回悬臂。 </li><li>适用于水对PNIPAM刷覆盖面下降，溶剂化的PNIPAM刷。 </li><li>抬起头，迅速取代PMMA表面经溶剂化PNIPAM表面创造了不混溶体系。交换表面时，为了避免从PMMA刷上的胶体探针的苯乙酮的蒸发快。 </li><li>接合尖端和表面上，并用相同的参数如先前记录的图像。 </li></ol>

<ol>
	<li>Lee, S., Spencer, N. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Materials+science+-+Sweet,+hairy,+soft,+and+slippery.">Materials science - Sweet, hairy, soft, and slippery.</a> Science. 319, 575-576 (2008).</li><li>Milner, S. T., Witten, T. A., Cates, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theory+of+the+Grafted+Polymer+Brush.">Theory of the Grafted Polymer Brush.</a> Macromolecules. 21, 2610-2619 (1988).</li><li>Klein, J., Kumacheva, E., Mahalu, D., Perahia, D., Fetters, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+Frictional+Forces+between+Solid-Surfaces+Bearing+Polymer+Brushes.">Reduction of Frictional Forces between Solid-Surfaces Bearing Polymer Brushes.</a> Nature. 370, 634-636 (1994).</li><li>Raviv, U., 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=Lubrication+by+charged+polymers.">Lubrication by charged polymers.</a> Nature. 425, 163-165 (2003).</li><li>Moro, T., 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=Surface+grafting+of+artificial+joints+with+a+biocompatible+polymer+for+preventing+periprosthetic+osteolysis.">Surface grafting of artificial joints with a biocompatible polymer for preventing periprosthetic osteolysis.</a> Nat Mater. 3, 829-836 (2004).</li><li>Bureau, L., Leger, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sliding+friction+at+a+rubber/brush+interface.">Sliding friction at a rubber/brush interface.</a> Langmuir. 20, 4523-4529 (2004).</li><li>Muller, M. T., Yan, X. P., Lee, S. W., Perry, S. S., Spencer, N. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lubrication+properties+of+a+brushlike+copolymer+as+a+function+of+the+amount+of+solvent+absorbed+within+the+brush.">Lubrication properties of a brushlike copolymer as a function of the amount of solvent absorbed within the brush.</a> Macromolecules. 38, 5706-5713 (2005).</li><li>Kobayashi, 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=Friction+behavior+of+high-density+poly(2-methacryloyloxyethyl+phosphorylcholine)+brush+in+aqueous+media.">Friction behavior of high-density poly(2-methacryloyloxyethyl phosphorylcholine) brush in aqueous media.</a> Soft Matter. 3, 740-746 (2007).</li><li>Zappone, B., Ruths, M., Greene, G. W., Jay, G. D., Israelachvili, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adsorption,+lubrication,+and+wear+of+lubricin+on+model+surfaces:+Polymer+brush-like+behavior+of+a+glycoprotein.">Adsorption, lubrication, and wear of lubricin on model surfaces: Polymer brush-like behavior of a glycoprotein.</a> Biophys J. 92, 1693-1708 (2007).</li><li>Sui, X. F., Zapotoczny, S., Benetti, E. M., Schon, P., Vancso, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+and+molecular+engineering+of+surface-grafted+polymer+brushes+across+the+length+scales+by+atomic+force+microscopy.">Characterization and molecular engineering of surface-grafted polymer brushes across the length scales by atomic force microscopy.</a> J Mater Chem. 20, 4981-4993 (2010).</li><li>Li, 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=Covalently+Cross-Linked+Hydrogel+Brushes+with+Tunable+Interfacial+and+Bulk+Properties.">Covalently Cross-Linked Hydrogel Brushes with Tunable Interfacial and Bulk Properties.</a> Macromolecules. 44, 5344-5351 (2011).</li><li>Wang, N., 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=Nanomechanical+and+tribological+characterization+of+the+MPC+phospholipid+polymer+photografted+onto+rough+polyethylene+implants.">Nanomechanical and tribological characterization of the MPC phospholipid polymer photografted onto rough polyethylene implants.</a> Colloid Surface B. 108, 285-294 (2013).</li><li>Yoshizawa, H., Chen, Y. -. L., Israelachvili, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fundemental+mechanisms+of+interfacial+friction.+1.+Relation+between+adhesion+and+friction.">Fundemental mechanisms of interfacial friction. 1. Relation between adhesion and friction.</a> J. Phys. Chem. 97, 4128-4140 (1993).</li><li>Maeda, N., Chen, N. H., Tirrell, M., Israelachvili, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adhesion+and+friction+mechanisms+of+polymer-on-polymer+surfaces.">Adhesion and friction mechanisms of polymer-on-polymer surfaces.</a> Science. 297, 379-382 (2002).</li><li>Klein, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shear,+friction,+and+lubrication+forces+between+polymer-bearing+surfaces.">Shear, friction, and lubrication forces between polymer-bearing surfaces.</a> Annu Rev Mater Sci. 26, 581-612 (1996).</li><li>Leger, L., Raphael, E., Hervet, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface-anchored+polymer+chains:+Their+role+in+adhesion+and+friction.">Surface-anchored polymer chains: Their role in adhesion and friction.</a> Adv Polym Sci. 138, 185-225 (1999).</li><li>Binder, K., Kreer, T., Milchev, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymer+brushes+under+flow+and+in+other+out-of-equilibrium+conditions.">Polymer brushes under flow and in other out-of-equilibrium conditions.</a> Soft Matter. 7, 7159-7172 (2011).</li><li>Galuschko, 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=Frictional+Forces+between+Strongly+Compressed,+Nonentangled+Polymer+Brushes:+Molecular+Dynamics+Simulations+and+Scaling+Theory.">Frictional Forces between Strongly Compressed, Nonentangled Polymer Brushes: Molecular Dynamics Simulations and Scaling Theory.</a> Langmuir. 26, 6418-6429 (2010).</li><li>Spirin, L., 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=Polymer-brush+lubrication+in+the+limit+of+strong+compression.">Polymer-brush lubrication in the limit of strong compression.</a> Eur Phys J E. 33, 307-311 (2010).</li><li>Schorr, P. A., Kwan, T. C. B., Kilbey, S. M., Shaqfeh, E. S. G., Tirrell, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Shear+forces+between+tethered+polymer+chains+as+a+function+of+compression,+sliding+velocity,+and+solvent+quality.">Shear forces between tethered polymer chains as a function of compression, sliding velocity, and solvent quality.</a> Macromolecules. 36, 389-398 (2003).</li><li>Drummond, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electric-Field-Induced+Friction+Reduction+and+Control.">Electric-Field-Induced Friction Reduction and Control.</a> Phys Rev Lett. 109, 154302 (2012).</li><li>Beer, S., Kutnyanszky, E., Sch&#246;n, P. M., Vancso, G. J., M&#252;ser, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solvent-induced+immiscibility+of+polymer+brushes+eliminates+dissipation+channels.">Solvent-induced immiscibility of polymer brushes eliminates dissipation channels.</a> Nat. Commun. 5, 3781 (2014).</li><li>Wong, T. S., 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=Bioinspired+self-repairing+slippery+surfaces+with+pressure-stable+omniphobicity.">Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity.</a> Nature. 477, 443-447 (2011).</li><li>Matyjaszewski, K., Xia, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atom+transfer+radical+polymerization.">Atom transfer radical polymerization.</a> Chem Rev. 101, 2921-2990 (2001).</li><li>Wagner, K., Cheng, P., Vezenov, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noncontact+Method+for+Calibration+of+Lateral+Forces+in+Scanning+Force+Microscopy.">Noncontact Method for Calibration of Lateral Forces in Scanning Force Microscopy.</a> Langmuir. 27, 4635-4644 (2011).</li><li>Green, C. P., 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=Normal+and+torsional+spring+constants+of+atomic+force+microscope+cantilevers.">Normal and torsional spring constants of atomic force microscope cantilevers.</a> Rev. Sci. Instrum. 75, 1988-1996 (2004).</li><li>Vyas, M. K., Schneider, K., Nandan, B., Stamm, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Switching+of+friction+by+binary+polymer+brushes.">Switching of friction by binary polymer brushes.</a> Soft Matter. 4, 1024-1032 (2008).</li><li>Persson, B. N. J., Albohr, O., Tartaglino, U., Volokitin, A. I., Tosatti, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+nature+of+surface+roughness+with+application+to+contact+mechanics,+sealing,+rubber+friction+and+adhesion.">On the nature of surface roughness with application to contact mechanics, sealing, rubber friction and adhesion.</a> J Phys-Condens Mat. 17, R1-R62 (2005).</li><li>Beer, S., M&#252;ser, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alternative+dissipation+mechanisms+and+the+effect+of+the+solvent+in+friction+between+polymer+brushes+on+rough+surfaces.">Alternative dissipation mechanisms and the effect of the solvent in friction between polymer brushes on rough surfaces.</a> Soft Matter. 9, 7234-7241 (2013).</li><li>Persson, B. N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theory+of+rubber+friction+and+contact+mechanics.">Theory of rubber friction and contact mechanics.</a> J Chem Phys. 115, 3840-3861 (2001).</li><li>Briels, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transient+forces+in+flowing+soft+matter.">Transient forces in flowing soft matter.</a> Soft Matter. 5, 4401-4411 (2009).</li><li>Chen, M., Briscoe, W. H., Armes, S. P., Klein, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lubrication+at+Physiological+Pressures+by+Polyzwitterionic+Brushes.">Lubrication at Physiological Pressures by Polyzwitterionic Brushes.</a> Science. 323, 1698-1701 (2009).</li></ol>

The authors have nothing to disclose.

所呈现的结果表明，该摩擦，对于单独溶剂化刷子不混溶体系，强烈降低相比于两个相同的溶剂化电刷传统混溶系统。在两个刷子的不同溶剂的优选吸收防止交错电刷和磨损和耗散在聚合物刷摩擦的结果的主要来源被消除。因此所提出的方法是从疏水性刷子，其中，所述摩擦将由刷特异性相互作用27来确定滑动干燥亲水根本的不同。事实上，在无溶剂的PNIPAM（折叠高度166纳米）剪切PMMA，我们发现，该摩擦是高出50％，较干燥的PMMA聚甲基丙烯酸甲酯（折叠高度236米）。 前面已经指出，短期内，在"协议"部分的笔记，有一对夫妇需要牢记执行，而关键点这些特殊的实验:首先，苯乙酮是一种用于PNIPAM比水更好的溶剂。因此，应注意的苯乙酮不被润湿PNIPAM刷用大量的水进入PNIPAM刷。由于苯乙酮和水不混合，苯乙酮，现在不能进入PNIPAM刷。这就是为什么我们并没有完全沉浸在我们的系统中苯乙酮，而是创造了一个苯乙酮毛细管的混溶体系。另一个原因是不完全的浸泡是完全沉浸结果太强大了流体力学，这样我们只测量胶体和悬臂斯托克斯阻力。其次，在AFM实验的扭转及正常弹簧常数耦合。悬臂具有低正常弹簧常数也将具有相对较低的扭转弹簧常数，反之亦然。这限制了最低可测量摩擦系数&gt; 10 -3。因此，为了测量的充分减小摩擦时，摩擦的误埚系统需要是高的。这是通过使用长的高密度刷子和通常为100米/秒的相对高的剪切速度来实现的。此外，电刷之间的毛细管也增加了摩擦力。我们测得的最低摩擦系数，对于不混溶的系统22中，μ= 0.003在200千帕的估计正常应力。使用相同的实验条件下，我们发现，μ= 0.15的混溶体系。 注意，该实验是在受控的实验室环境中进行的，并且在工业中使用的表面并不在所呈现的实验中所用的理想的。最表面具有不均匀的凹凸分布28并且因此许多不同的形状和大小的凹凸。在两个电刷承载凹凸的碰撞，摩擦是由出不同耗散通道29。旁边稳态散热机制，如interdigita化和溶剂流，将有在形状30滞后效应是由于聚合物和溶剂的缓慢弛豫时间。此外，毛细管形成和破裂。在传统上使用的可混溶刷系统，短暂交错结合31放大形状-和毛细管迟滞。与这里介绍的不混溶系统，瞬间交错结合被淘汰了。此外，毛细管滞后可以通过应用程序的两个不相混溶的溶剂进行规避。因此，也为更常见粗糙表面，摩擦和磨损将使用不混溶的刷系统22减小。摩擦的主要来源，剩下的就是刷变形。锚固polyzwitterionic聚合物，它们是众所周知的固有低摩擦32，上表面中的一个可以最大限度地减少了后者。在这样的系统中所用溶剂的渗透压高，导致高的正常负载下的小刷子变形。 该不混溶的刷系统的方法能够在几乎所有的系统，其中低摩擦期望被应用。该方法的功能以及在高压下。然而，应注意，该温度保持周围室温。高温损坏的聚合物，这会导致液体流出接触，因此高的摩擦。潜在的应用的实例是:针筒，活塞系统，车轴轴承和铰链。

完美润滑剂减少摩擦和磨损在即使当正常负载高的相对运动的固体。为了实现这一目标，润滑剂应该在滑动和在休息留在接触。然而，一个正正常负荷下，简单，低粘度液体被快速挤出来的接触面积和更高粘度的油最终被排出。然而，生物接触，例如 ，在人的关节，保持润滑用的低粘度流体在任何时候。自然实现了使用连接到固体表面1的糖链效率等的润滑。亲水糖链保持含水液体中提供的正常压力不超过的溶剂2中的渗透压的接触。因此，大量的努力已针对通过接枝形成所谓的聚合物刷3-12的聚合物固体表面模仿生物润滑剂。 当两个对立的聚合物电刷接触，在一侧上的聚合物链段可在相反侧移动到刷子链段。这种效应被称为交错结合13。当刷子处于相对滑动运动，交错结合是磨损14和摩擦15-17的主要来源。事实上，最近，滑动聚合物刷摩擦速度的关系已经得到18。这些缩放法是基于交错结合以及由此引发的拉伸和聚合物的后滑动弯曲。其主要特点同意的表面力装置的实验结果19和分子动力学（MD）的仿真20。在后者的重叠程度可以直接定量。此外，它表明，聚电解质刷子之间的重叠可以通过施加电场21被调谐。因此，如果交错结合可以回避，摩擦磨损在这些系统将是significanTLY减少。 在最近出版的22，我们通过MD模拟两个不相混溶溶剂化聚合物刷系统，防止刷之间的重叠显示。此外，当滑动的电刷，我们发现了降低摩擦力的由两个数量级相比传统混溶刷系统，在与我们的原子力显微镜（AFM）测量非常吻合。在这里，我们详细介绍一下如何设置参考的AFM实验。 22.基本原理是描绘在图1中。在两个反向的表面，两个不同的刷子，各由自己的优选的溶剂溶剂化的，也是需要的。在这种结构中，每个刷子保持在其自己的溶剂中进行。因此，从一个刷聚合物链段不渗入其他刷。聚（甲基丙烯酸甲酯）（PMMA）是从AFM胶体探针接枝和刷由苯乙酮溶剂化。从平坦表面聚（N- -isopropylacrylamide）（PNIPAM）被嫁接和溶解在水中。为了比较本发明的系统与传统的系统可混溶，第二平坦对置表面带有一个聚甲基丙烯酸甲酯刷溶解在苯乙酮制成。当上滑动PNIPAM PMMA的不混溶体系所测量摩擦力为聚甲基丙烯酸甲酯的聚甲基丙烯酸甲酯的可混溶体系的摩擦力大约1％。需要注意的是，使用这些特定刷系统的仅是一个例子。该方法是通用的，适用由于在不同的刷子的溶剂的优选的吸光度。因此，多种类型的刷子的预计是适用的，只要所选择的溶剂脱混合的两个电刷。该效果是通过使用两个非混合溶剂（如苯乙酮和水），使得一个额外的滑溜的流体上的流体滑动界面创建22,23放大。

<table><tbody><tr><td>Methyl methacrylate</td><td>Sigma-Aldrich</td><td>M55909&amp;nbsp;</td><td>Monomer for PMMA synthesis, cleaned by pressing through a basic alumina column</td></tr><tr><td>(3-aminopropyl)triethoxysilane</td><td>Sigma-Aldrich</td><td>440140</td><td>vapor deposited silane monolayer</td></tr><tr><td>triethylamine</td><td>Sigma-Aldrich</td><td>T0886</td><td>Reagent for the ATRP initiator moiety coupling.</td></tr><tr><td>2-bromo-2-methylpropionyl</td><td>Sigma-Aldrich</td><td>252271</td><td>ATRP initiator moiety.</td></tr><tr><td>toluene</td><td>Biosolve</td><td>20150501</td><td>Coupling medium for ATRP moiety</td></tr><tr><td>CuBr</td><td>Sigma-Aldrich</td><td>212865</td><td>ATRP catalyst.</td></tr><tr><td>2,2&amp;prime;-Bipyridyl</td><td>Sigma-Aldrich</td><td>14453</td><td>Cu complexing ligand for ATRP of MMA</td></tr><tr><td>&lt;em&gt;N,N,N&amp;prime;,N&quot;,N&quot;&lt;/em&gt;-Pentamethyldiethylenetriamine</td><td>Sigma-Aldrich</td><td>369497</td><td>Cu complexing ligand for ATRP of NIPAM</td></tr><tr><td>acetic acid 98-100%</td><td>Merck</td><td>8187551000</td><td>For cleaning CuBr.</td></tr><tr><td>Sulfuric acid</td><td>Sigma-Aldrich</td><td>320501</td><td>For the preparation of Piranha solution</td></tr><tr><td>Hydrogen peroxide 33%</td><td>Merck</td><td>1.07210.1000</td><td>For the preparation of Piranha solution</td></tr><tr><td>Ethanol</td><td>Merck</td><td>1.00983.1000</td><td>For cleaning substrates.</td></tr><tr><td>Basic aluminum oxide 60&amp;nbsp;</td><td>Merck</td><td></td><td>For cleaning monomers.</td></tr><tr><td>Chloroform</td><td>Biosolve</td><td>3080501</td><td>For monolayer deposition and substrate cleaning.</td></tr><tr><td>Methanol</td><td>Biosolve</td><td>13680501</td><td>For polymerization medium.</td></tr><tr><td>Acetophenone</td><td>Acros Organics</td><td>102410010</td><td>For AFM measurement environment.</td></tr><tr><td>&lt;em&gt;N&lt;/em&gt;-isopropyl acrylamide</td><td>Acros Organics</td><td>412780250</td><td>Monomer for PNIPAM synthesis, recrystallized from toluene/hexane</td></tr><tr><td>Poly(ethylene glycol) methacrylate&amp;nbsp;</td><td>Sigma-Aldrich</td><td>409529</td><td>Monomer for Si-POEGMA synthesis, cleaned by pressing through a basic alumina column.</td></tr><tr><td>MilliQ water</td><td>MilliQ Advantage A 10 purification system&amp;nbsp;</td><td></td><td>ATRP medium, AFM measurement environment and for substrate cleaning.</td></tr><tr><td>Silicon substrates&amp;nbsp;</td><td></td><td></td><td></td></tr><tr><td>Gold coated substrates</td><td></td><td></td><td></td></tr><tr><td>AFM probe, CP-FM-Au</td><td>SQube</td><td></td><td>AFM measurement</td></tr><tr><td colspan="4">[header]</td></tr><tr><td>dithiodiundecane-11,1-diybis[2-bromo-2-methlpropanoate] (DTPR)</td><td></td><td></td><td>Initiator, for Si-ATRP on gold surfaces.&lt;br/&gt; Synthesized according to &lt;em&gt;Macromolecules&lt;/em&gt;, &lt;strong&gt;33&lt;/strong&gt;, 597-605 (2000).</td></tr><tr><td>Atomic Frorce Microscope</td><td>Bruker Multimode V controller</td><td></td><td></td></tr></tbody></table>

preparation and friction force microscopy measurements of immiscible, opposing polymer brushes

溶剂化的聚合物刷是公知的润滑高压触点，因为它们能够维持正正常负载，同时保持低摩擦界面处。然而，这些系统可以是敏感穿由于相对的电刷交错​​结合。在最近的出版物中，我们已经通过分子动力学模拟和原子力显微术实验显示，在使用不混溶的聚合物刷系统终止所述基板和滑块的表面，分别可以消除这种交错结合。因此，穿在接触被减少。此外，该摩擦力是两个数量级低相比传统混溶聚合物刷的系统。因此，这一新提议的系统保持着在行业中的应用潜力巨大。这里，该方法来构建两种不同的刷子各由自己的优选的溶剂溶剂化的不混溶的聚合物刷系统呈现。如何嫁接P程序OLY（N- -isopropylacrylamide）从一个原子力显微镜（AFM）的胶体探针（PNIPAM）从一个平坦表面和聚（甲基丙烯酸甲酯）（PMMA）进行说明。 PNIPAM被溶解在水和PMMA中苯乙酮。通过摩擦力AFM测量，它表明，用于该系统的摩擦力确实由两个数量级减少相比的PMMA聚甲基丙烯酸甲酯的可混溶体系溶解在苯乙酮。

图4示出在滑动两者混溶和不混溶的聚合物刷系统代表的AFM力痕迹。摩擦力F是由摩擦力归在稳态滑动˚F 符号为对称的，可混溶体系。刷的高度在这些实验肿是1010纳米的PMMA和532纳米的PNIPAM。力痕迹按照议定书节中描述的步骤后抓获。在这些实验中，表面被来回移动用80微米/秒的速度v，同时施加30 NN正常负载。在为可混溶（左图）摩擦力和不混溶的（右面板）刷系统的差异可以清楚地观察到。在左侧面板中的稳态摩擦力比右侧面板中的稳态摩擦力90X高。对于不混溶的系统测得的摩擦力通常所测量的摩擦力F的0.5-2％或混溶体系。虽然确切的摩擦减少取决于接枝密度，聚合度，溶剂的量，和（弱）上的正常负载和滑动速度，它始终是围绕两个数量级。若增加用于通过一个因子5（以400微米/秒）以上所描述的系统中的滑动速度，摩擦减少了2％降低。如果我们增加了正常负荷由10倍（300 NN），摩擦减少3％下降。 <img alt="图1" src="/files/ftp_upload/52285/52285fig1highres.jpg" /> 图1的安装的示意图草图。左面板显示混溶体系，其中相同的聚合物是由在表面和胶体接枝。电刷被溶解在单相液体。右侧面板示出了两个不同的聚合物刷的不混溶体系。每刷溶解在自己首选的液体。在传统混溶系统相反电刷的聚合物重叠。对于不混溶体系，相对刷不互相交叉，使得摩擦和滑动操作时的磨损。 <img alt="图2" src="/files/ftp_upload/52285/52285fig2highres.jpg" width="700px" /> 如在协议部分中描述的样品的制备过程的图2示意图草图。从左至右示出了刷子的准备通过引发剂沉积和表面引发的原子转移自由基聚合（ATRP SI）的过程。路径（A）描述了从硅表面嫁接的画笔，（B）从刷镀金硅表面和（C）刷子从胶体金上的原子力显微镜探针嫁接。 <a href="https://www.jove.com/files/ftp_upload/52285/52285fig2highres.jpg" target="_blank">请点击此处查看人</a>arger版本，这个数字。 <img alt="图3" src="/files/ftp_upload/52285/52285fig3highres.jpg" /> 聚甲基丙烯酸甲酯（蓝色）和PNIPAM（绿色）的图3 FTIR光谱刷上硅（粗线）和金（细线），数据取自增刊。垫。的参考。 22. PMMA波数（厘米- 1）:3,050-2,990（CH伸缩振动），1730 C = O（双键的伸缩振动），1450（CH 3和CH 2变形振动），1,260-1,040（COC单键伸缩振动），880-960（COC单键变形振动）。在1730厘米- 1的C = O基的特征伸缩振动峰是显而易见PNIPAM波数（厘米-1）:3289（NH对称和非对称伸缩振动），3078，2971，2933，2874（非对称和对称CH伸缩。振动-CH &lt;子&gt; 2 - ），1635（C = O伸缩振动），1535（酰胺Ⅱ），1458（CH不对称弯曲变形），1386（CH对称弯曲变形），1,366-1,170（CN不对称伸缩振动）。在1635和1535厘米- 1的酰胺基团的特征伸缩振动峰是显而易见的。 <img alt="图4" src="/files/ftp_upload/52285/52285fig4highres.jpg" width="700px" /> 图4.平均，过滤并在滑动混溶（左）和不混溶的（右）系统平滑力痕迹（来自参考文献的调整。22），表面被来回移动40微米，在一扫描速率为1Hz和30 NN正常负荷。

Watch this Scientific Journal Video about Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes at JoVE.com

Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes

The methodology to perform friction force microscopy experiments for contacting brushes is presented: Two polymer brushes that are grafted from (a) substrates and (b) colloidal probes are slid to show that, by using two contacting immiscible brush systems, friction in sliding contacts is reduced compared to miscible brush systems.

互溶的测量准备和摩擦力显微镜，反对聚合物刷

Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low ...

preparation-friction-force-microscopy-measurements-immiscible

Research

JoVE Journal

Engineering

14.0K 次观看.  Forschungszentrum Jülich. The methodology to perform friction force microscopy experiments for contacting brushes is presented: Two polymer brushes that are grafted from (a) substrates and (b) colloidal probes are slid to show that, by using two contacting immiscible brush systems, friction in sliding contacts is reduced compared to miscible brush systems.

视频: Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes

Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures

The behavior of confined colloidal suspensions with attractive interparticle interactions is critical to the rational design of materials for directed assembly1-3, drug delivery4, improved hydrocarbon recovery5-7, and flowable electrodes for energy storage8. Suspensions containing fluorescent colloids and non-adsorbing polymers are appealing model systems, as the ratio of the polymer radius of gyration to the particle radius&#160;and concentration of polymer control the range and strength of the interparticle attraction, respectively. By tuning the polymer properties and the volume fraction of the colloids, colloid fluids, fluids of clusters, gels, crystals, and glasses can be obtained9.&#160;Confocal microscopy, a variant of fluorescence microscopy, allows an optically transparent and fluorescent sample to be imaged with high spatial and temporal resolution in three dimensions. In this technique, a small pinhole or slit blocks the emitted fluorescent light from regions of the sample that are outside the focal volume of the microscope optical system. As a result, only a thin section of the sample in the focal plane is imaged. This technique is particularly well suited to probe the structure and dynamics in dense colloidal suspensions at the single-particle scale: the particles are large enough to be resolved using visible light and diffuse slowly enough to be captured at typical scan speeds of commercial confocal systems10. Improvements in scan speeds and analysis algorithms have also enabled quantitative confocal imaging of flowing suspensions11-16,37.&#160;In this paper, we demonstrate confocal microscopy experiments to probe the confined phase behavior and flow properties of colloid-polymer mixtures. We first prepare colloid-polymer mixtures that are density- and refractive-index matched. Next, we report a standard protocol for imaging quiescent dense colloid-polymer mixtures under varying confinement in thin wedge-shaped cells. Finally, we demonstrate a protocol for imaging colloid-polymer mixtures during microchannel flow.

Confocal microscopy is used to image quiescent and flowing colloid-polymer mixtures, which are studied as model systems for attractive suspensions. Image analysis algorithms are used to calculate structural and dynamic metrics for the colloidal particles that measure changes due to geometric confinement.

密闭静态和流动胶体聚合物混合物的共聚焦成像

The behavior of confined colloidal suspensions with attractive interparticle interactions is critical to the rational design of materials for directed ...

科研

化学

Quantitative and Qualitative Examination of Particle-particle Interactions Using Colloidal Probe Nanoscopy

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate using the Atomic Force Microscope (AFM), can provide key insights into physical interactions present within colloidal systems. Colloidal systems are widely existent in several applications including, pharmaceuticals, foods, paints, paper, soil and minerals, detergents, printing and much more.1-3 Furthermore, colloids can exist in many states such as emulsions, foams and suspensions. Using colloidal probe nanoscopy one can obtain key information on the adhesive properties, binding energies and even gain insight into the physical stability and coagulation kinetics of the colloids present within. Additionally, colloidal probe nanoscopy can be used with biological cells to aid in drug discovery and formulation development. In this paper we describe a method for conducting colloidal probe nanoscopy, discuss key factors that are important to consider during the measurement, and show that both quantitative and qualitative data that can be obtained from such measurements.

Colloidal probe nanoscopy can be used within a variety of fields to gain insight into the physical stability and coagulation kinetics of colloidal systems and aid in drug discovery and formulation sciences using biological systems. The method described within provides a quantitative and qualitative means to study such systems.

粒子粒子相互作用采用胶体探针纳米显微定量和定性检查

Colloidal Probe Nanoscopy (CPN), the study of the nano-scale interactive forces between a specifically prepared colloidal probe and any chosen substrate ...

Investigating Single Molecule Adhesion by Atomic Force Spectroscopy

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. At the same time the AFM tip is passivated to prevent unspecific interactions between the tip and the substrate, which is a prerequisite to study single molecules attached to the AFM tip. Analyses to determine the adhesion force, the adhesion length, and the free energy of these molecules on solid surfaces and bio-interfaces are shortly presented and external references for further reading are provided. Example molecules are the poly(amino acid) polytyrosine, the graft polymer PI-g-PS and the phospholipid POPE (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine). These molecules are desorbed from different surfaces like CH3-SAMs, hydrogen terminated diamond and supported lipid bilayers under various solvent conditions. Finally, the advantages of force spectroscopic single molecule experiments are discussed including means to decide if truly a single molecule has been studied in the experiment.

A protocol to couple a large variety of single molecules covalently onto an AFM tip is presented. Procedures and examples to determine the adhesion force and free energy of these molecules on solid supports and bio-interfaces are provided.

调查单分子粘附的原子力谱

Atomic force spectroscopy is an ideal tool to study molecules at surfaces and interfaces. An experimental protocol to couple a large variety of single ...

工程学

Prescribed 3-D Direct Writing of Suspended Micron/Sub-micron Scale Fiber Structures via a Robotic Dispensing System

A 3-axis dispensing system is utilized to control the initiating and terminating fiber positions and trajectory via the dispensing software. The polymer fiber length and orientation is defined by the spatial positioning of the dispensing system 3-axis stages. The fiber diameter is defined by the prescribed dispense time of the dispensing system valve, the feed rate (the speed at which the stage traverses from an initiating to a terminating position), the gauge diameter of the dispensing tip, the viscosity and surface tension of the polymer solution, and the programmed drawing length. The stage feed rate affects the polymer solution&#8217;s evaporation rate and capillary breakup of the filaments. The dispensing system consists of a pneumatic valve controller, a droplet-dispensing valve and a dispensing tip. Characterization of the direct write process to determine the optimum combination of factors leads to repeatedly acquiring the desired range of fiber diameters. The advantage of this robotic dispensing system is the ease of obtaining a precise range of micron/sub-micron fibers onto a desired, programmed location via automated process control. Here, the discussed self-assembled micron/sub-micron scale 3D structures have been employed to fabricate suspended structures to create micron/sub-micron fluidic devices and bioengineered scaffolds.

Here, we present a protocol to fabricate freely-suspended, micron/sub-micron scale polymer fibers and &#8220;web-like&#8221; structures generated via automated direct writing procedure by means of a 3-axis dispensing system.

暂停规定微米/亚微米尺度的纤维结构的3-D直写经全自动点胶系统

A 3-axis dispensing system is utilized to control the initiating and terminating fiber positions and trajectory via the dispensing software. The polymer ...

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives

A facile method for the preparation of polycarbodiimide-based secondary structures (e.g., nano-rings, &#34;craters,&#34; fibers, looped fibers, fibrous networks, ribbons, worm-like aggregates, toroidal structures, and spherical particles) is described. These aggregates are morphologically influenced by extensive hydrophobic side chain-side chain interactions of the singular polycarbodiimide strands, as inferred by atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques. Polycarbodiimide-g-polystyrene copolymers (PS-PCDs) were prepared by a combination of synthetic methods, including coordination-insertion polymerization, copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) &#34;click&#34; chemistry, and atom transfer radical polymerization (ATRP). PS-PCDs were found to form specific toroidal architectures at low concentrations in CHCl3. To determine the influence of a more polar solvent medium (i.e., THF and THF/EtOH) on polymer aggregation behavior, a number of representative PS-PCD composites have been tested to show discrete concentration-dependent spherical particles. These fundamental studies are of practical interest to the development of experimental procedures for desirable architectures by directed self-assembly in thin film. These architectures may be exploited as drug carriers, whereas other morphological findings represent certain interest in the area of novel functional materials.

Here, we present a protocol to prepare and visualize secondary structures (e.g., fibers, toroidal architectures, and nano-spheres) derived from helical polycarbodiimides. The morphology characterized by both atomic force microscopy (AFM) and scanning electron microscopy (SEM) was shown to depend on molecular structure, concentration, and the solvent of choice.

从螺旋聚碳化二亚胺共聚物及其三唑衍生物获得自组装形貌

A facile method for the preparation of polycarbodiimide-based secondary structures (e.g., nano-rings, &#34;craters,&#34; fibers, looped fibers, fibrous ...

Sample Preparation in Quartz Crystal Microbalance Measurements of Protein Adsorption and Polymer Mechanics

In this study, we present various examples of how thin film preparation for quartz crystal microbalance experiments informs the appropriate modeling of the data and determines which properties of the film can be quantified. The quartz crystal microbalance offers a uniquely sensitive platform for measuring fine changes in mass and/or mechanical properties of an applied film by observing the changes in mechanical resonance of a quartz crystal oscillating at high frequency. The advantages of this approach include its experimental versatility, ability to study changes in properties over a wide range of experimental time lengths, and the use of small sample sizes. We demonstrate that, based on the thickness and shear modulus of the layer deposited on the sensor, we can acquire different information from the material. Here, this concept is specifically exploited to display experimental parameters resulting in mass and viscoelastic calculations of adsorbed collagen on gold and polyelectrolyte complexes during swelling as a function of salt concentration.

The quartz crystal microbalance can provide accurate mass and viscoelastic properties for films in the micron or submicron range, which is relevant for investigations in biomedical and environmental sensing, coatings, and polymer science. The sample thickness influences which information can be obtained from the material in contact with the sensor.

石英晶体微平衡测量中的蛋白质吸附和聚合物力学的样品制备

In this study, we present various examples of how thin film preparation for quartz crystal microbalance experiments informs the appropriate modeling of ...

Covalent Attachment of Single Molecules for AFM-based Force Spectroscopy

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and surfaces. For a true single molecule experiment, covalent attachment of the probe molecule is essential because only then can hundreds of force-extension traces with one and the same single molecule be obtained. Many traces are in turn necessary to prove that a single molecule alone is probed. Additionally, passivation is crucial for preventing unwanted interactions between the single probe molecule and the AFM cantilever tip as well as between the AFM cantilever tip and the underlying surface. The functionalization protocol presented here is reliable and can easily be applied to a variety of polymers. Characteristic single molecule events (i.e., stretches and plateaus) are detected in the force-extension traces. From these events, physical parameters such as stretching force, desorption force and desorption length can be obtained. This is particularly important for the precise investigation of stimuli-responsive systems at the single molecule level. As exemplary systems poly(ethylene glycol) (PEG), poly(N-isopropylacrylamide) (PNiPAM) and polystyrene (PS) are stretched and desorbed from SiOx (for PEG and PNiPAM) and from hydrophobic self-assembled monolayer surfaces (for PS) in aqueous environment.

Covalent attachment of probe molecules to atomic force microscopy (AFM) cantilever tips is an essential technique for the investigation of their physical properties. This allows us to determine the stretching force, desorption force and length of polymers via AFM-based single molecule force spectroscopy with high reproducibility.

基于AFM的力光谱单分子共价附价

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and ...

Atomic Force Microscopy Cantilever-Based Nanoindentation: Mechanical Property Measurements at the Nanoscale in Air and Fluid

An atomic force microscope (AFM) fundamentally measures the interaction between a nanoscale AFM probe tip and the sample surface. If the force applied by the probe tip and its contact area with the sample can be quantified, it is possible to determine the nanoscale mechanical properties (e.g., elastic or Young&#39;s modulus) of the surface being probed. A detailed procedure for performing quantitative AFM cantilever-based nanoindentation experiments is provided here, with representative examples of how the technique can be applied to determine the elastic moduli of a wide variety of sample types, ranging from kPa to GPa. These include live mesenchymal stem cells (MSCs) and nuclei in physiological buffer, resin-embedded dehydrated loblolly pine cross-sections, and Bakken shales of varying composition.
Additionally, AFM cantilever-based nanoindentation is used to probe the rupture strength (i.e., breakthrough force) of phospholipid bilayers. Important practical considerations such as method choice and development, probe selection and calibration, region of interest identification, sample heterogeneity, feature size and aspect ratio, tip wear, surface roughness, and data analysis and measurement statistics are discussed to aid proper implementation of the technique. Finally, co-localization of AFM-derived nanomechanical maps with electron microscopy techniques that provide additional information regarding elemental composition is demonstrated.

Quantifying the contact area and force applied by an atomic force microscope (AFM) probe tip to a sample surface enables nanoscale mechanical property determination. Best practices to implement AFM cantilever-based nanoindentation in air or fluid on soft and hard samples to measure elastic modulus or other nanomechanical properties are discussed.

原子力显微镜悬臂式纳米压痕:空气和流体中纳米级机械性能测量

An atomic force microscope (AFM) fundamentally measures the interaction between a nanoscale AFM probe tip and the sample surface. If the force applied by ...

Automation of Bio-Atomic Force Microscope Measurements on Hundreds of C. albicans Cells

The method presented in this paper aims to automate Bio-AFM experiments and the recording of force curves. Using this method, it is possible to record forces curves on 1000 cells in 4 hours automatically. To maintain a 4 hour analysis time, the number of force curves per cell is reduced to 9 or 16. The method combines a Jython based program and a strategy for assembling cells on defined patterns. The program, implemented on a commercial Bio-AFM, can center the tip on the first cell of the array and then move, automatically, from cell to cell while recording force curves on each cell. Using this methodology, it is possible to access the biophysical parameters of the cells such as their rigidity, their adhesive properties, etc. With the automation and the large number of cells analyzed, one can access the behavior of the cell population. This is a breakthrough in the Bio-AFM field where data have, so far, been recorded on only a few tens of cells.

Automation of Bio-Atomic Force Microscope Measurements on Hundreds of C. albicans Cells

This protocol aims to automate AFM measurements on hundreds of microbial cells. First, microbes are immobilized into PDMS stamp microstructures and then force spectroscopy measurements are performed automatically on hundreds of immobilized cells.

数百个 C.白化病 细胞生物原子力显微镜测量自动化

The method presented in this paper aims to automate Bio-AFM experiments and the recording of force curves. Using this method, it is possible to record ...

生物工程

Protrusion Force Microscopy: A Method to Quantify Forces Developed by Cell Protrusions

In numerous biological contexts, animal cells need to interact physically with their environment by developing mechanical forces. Among these, traction forces have been well-characterized, but there is a lack of techniques allowing the measurement of the protrusion forces exerted by cells orthogonally to their substrate. We designed an experimental setup to measure the protrusion forces exerted by adherent cells on their substrate. Cells plated on a compliant Formvar sheet deform this substrate and the resulting topography is mapped by atomic force microscopy (AFM) at the nanometer scale. Force values are then extracted from an analysis of the deformation profile based on the geometry of the protrusive cellular structures. Hence, the forces exerted by the individual protruding units of a living cell can be measured over time. This technique will enable the study of force generation and its regulation in the many cellular processes involving protrusion. Here, we describe its application to measure the protrusive forces generated by podosomes formed by human macrophages.

Here, we detail the experimental techniques used to evaluate the protrusion forces that podosomes apply on a compliant film, from the preparation of the film to the automated analysis of topographical images.

凸出力显微镜: 一种量化细胞突起力的方法

In numerous biological contexts, animal cells need to interact physically with their environment by developing mechanical forces. Among these, traction ...

互溶的测量准备和摩擦力显微镜，反对聚合物刷

摘要

探索更多视频

此视频中的章节

密闭静态和流动胶体聚合物混合物的共聚焦成像

粒子粒子相互作用采用胶体探针纳米显微定量和定性检查

调查单分子粘附的原子力谱

暂停规定微米/亚微米尺度的纤维结构的3-D直写经全自动点胶系统

从螺旋聚碳化二亚胺共聚物及其三唑衍生物获得自组装形貌

石英晶体微平衡测量中的蛋白质吸附和聚合物力学的样品制备

基于AFM的力光谱单分子共价附价

原子力显微镜悬臂式纳米压痕:空气和流体中纳米级机械性能测量

数百个 C.白化病细胞生物原子力显微镜测量自动化

凸出力显微镜: 一种量化细胞突起力的方法

互溶的测量准备和摩擦力显微镜，反对聚合物刷

摘要

探索更多视频

此视频中的章节

密闭静态和流动胶体聚合物混合物的共聚焦成像

粒子粒子相互作用采用胶体探针纳米显微定量和定性检查

调查单分子粘附的原子力谱

暂停规定微米/亚微米尺度的纤维结构的3-D直写经全自动点胶系统

从螺旋聚碳化二亚胺共聚物及其三唑衍生物获得自组装形貌

石英晶体微平衡测量中的蛋白质吸附和聚合物力学的样品制备

基于AFM的力光谱单分子共价附价

原子力显微镜悬臂式纳米压痕:空气和流体中纳米级机械性能测量

数百个 C.白化病 细胞生物原子力显微镜测量自动化

凸出力显微镜: 一种量化细胞突起力的方法

数百个 C.白化病细胞生物原子力显微镜测量自动化