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>

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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. 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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 border="0" cellpadding="0" cellspacing="0" width="974">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:241px;">Name of Material/ Equipment</td>
			<td style="width:108px;">Company</td>
			<td style="width:105px;">Catalog Number</td>
			<td style="width:520px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:241px;"></td>
			<td style="width:108px;"></td>
			<td style="width:105px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Methyl methacrylate</td>
			<td style="width:108px;">Sigma-Aldrich</td>
			<td>M55909&#160;</td>
			<td>Monomer for PMMA synthesis, cleaned by pressing through a basic alumina column</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3-aminopropyl)triethoxysilane</td>
			<td style="width:108px;">Sigma-Aldrich</td>
			<td>440140</td>
			<td>vapor deposited silane monolayer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:241px;">triethylamine</td>
			<td style="width:108px;">Sigma-Aldrich</td>
			<td>T0886</td>
			<td>Reagent for the ATRP initiator moiety coupling.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2-bromo-2-methylpropionyl</td>
			<td style="width:108px;">Sigma-Aldrich</td>
			<td>252271</td>
			<td>ATRP initiator moiety.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:241px;">toluene</td>
			<td style="width:108px;">&#160;Biosolve</td>
			<td style="width:105px;">20150501</td>
			<td>Coupling medium for ATRP moiety</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CuBr</td>
			<td style="width:108px;">Sigma-Aldrich</td>
			<td>212865</td>
			<td>ATRP catalyst.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2,2&#8242;-Bipyridyl</td>
			<td style="width:108px;">Sigma-Aldrich</td>
			<td>14453</td>
			<td>Cu complexing ligand for ATRP of MMA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">N,N,N&#8242;,N&#8242;&#8242;,N&#8242;&#8242;-Pentamethyldiethylenetriamine</td>
			<td style="width:108px;">Sigma-Aldrich</td>
			<td>369497</td>
			<td>Cu complexing ligand for ATRP of NIPAM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">acetic acid 98-100%</td>
			<td style="width:108px;">Merck</td>
			<td>8187551000</td>
			<td>For&#160; cleaning CuBr.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sulfuric acid</td>
			<td style="width:108px;">Sigma-Aldrich</td>
			<td>320501</td>
			<td>For the preparation of Piranha solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:241px;">Hydrogen peroxide 33%</td>
			<td style="width:108px;">&#160;Merck</td>
			<td style="width:105px;">&#160;1.07210.1000</td>
			<td>For the preparation of Piranha solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ethanol</td>
			<td style="width:108px;">&#160;Merck</td>
			<td style="width:105px;">1.00983.1000</td>
			<td>For cleaning substrates.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Basic aluminum oxide 60&#160;</td>
			<td style="width:108px;">&#160;Merck</td>
			<td style="width:105px;"></td>
			<td>For cleaning monomers.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Chloroform</td>
			<td style="width:108px;">&#160;Biosolve</td>
			<td style="width:105px;">3080501</td>
			<td>For monolayer deposition and substrate cleaning.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:241px;">Methanol</td>
			<td style="width:108px;">&#160;Biosolve</td>
			<td style="width:105px;">13680501</td>
			<td>For polymerization medium.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acetophenone</td>
			<td style="width:108px;">Acros Organics</td>
			<td>&#160;102410010</td>
			<td>For AFM measurement environment.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">N-isopropyl acrylamide</td>
			<td style="width:108px;">Acros Organics</td>
			<td>412780250</td>
			<td>Monomer for PNIPAM synthesis, recrystallized from toluene/hexane</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Poly(ethylene glycol) methacrylate&#160;</td>
			<td style="width:108px;">Sigma-Aldrich</td>
			<td>409529</td>
			<td>Monomer for Si-POEGMA synthesis, cleaned by pressing through a basic alumina column.</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;">MilliQ water</td>
			<td style="width:108px;">MilliQ Advantage A 10 purification system&#160;</td>
			<td style="width:105px;"></td>
			<td style="width:520px;">ATRP medium, AFM measurement environment 
			and for substrate cleaning.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Silicon substrates&#160;</td>
			<td style="width:108px;"></td>
			<td style="width:105px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:241px;">Gold coated substrates</td>
			<td style="width:108px;"></td>
			<td style="width:105px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:241px;">AFM probe, CP-FM-Au,&#160;</td>
			<td style="width:108px;">SQube</td>
			<td style="width:105px;"></td>
			<td>AFM measurement</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:241px;"></td>
			<td style="width:108px;"></td>
			<td style="width:105px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:241px;">dithiodiundecane-11,1-diybis[2-bromo-2-methlpropanoate] (DTPR)</td>
			<td style="width:108px;"></td>
			<td style="width:105px;"></td>
			<td style="width:520px;">Initiator, for Si-ATRP on gold surfaces. 
			Synthesized according to Macromolecules, 2000, 33,597.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:241px;"></td>
			<td style="width:108px;"></td>
			<td style="width:105px;"></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Atomic Frorce Microscope</td>
			<td colspan="2">Bruker Multimode V controller</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

13.9K 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

Atomic Force Microscopy of Red-Light Photoreceptors Using PeakForce Quantitative Nanomechanical Property Mapping

Atomic force microscopy (AFM) uses a pyramidal tip attached to a cantilever to probe the force response of a surface. The deflections of the tip can be measured to ~10 pN by a laser and sectored detector, which can be converted to image topography. Amplitude modulation or &#8220;tapping mode&#8221; AFM involves the probe making intermittent contact with the surface while oscillating at its resonant frequency to produce an image. Used in conjunction with a fluid cell, tapping-mode AFM enables the imaging of biological macromolecules such as proteins in physiologically relevant conditions. Tapping-mode AFM requires manual tuning of the probe and frequent adjustments of a multitude of scanning parameters which can be challenging for inexperienced users. To obtain high-quality images, these adjustments are the most time consuming.
PeakForce Quantitative Nanomechanical Property Mapping (PF-QNM) produces an image by measuring a force response curve for every point of contact with the sample. With ScanAsyst software, PF-QNM can be automated. This software adjusts the set-point, drive frequency, scan rate, gains, and other important scanning parameters automatically for a given sample. Not only does this process protect both fragile probes and samples, it significantly reduces the time required to obtain high resolution images. PF-QNM is compatible for AFM imaging in fluid; therefore, it has extensive application for imaging biologically relevant materials.
The method presented in this paper describes the application of PF-QNM to obtain images of a bacterial red-light photoreceptor, RpBphP3 (P3), from photosynthetic R. palustris in its light-adapted state. Using this method, individual protein dimers of P3 and aggregates of dimers have been observed on a mica surface in the presence of an imaging buffer. With appropriate adjustments to surface and/or solution concentration, this method may be generally applied to other biologically relevant macromolecules and soft materials.

A method for investigating the structure of a protein photoreceptor using atomic force microscopy (AFM) is described in this paper. PeakForce Quantitative Nanomechanical Property Mapping (PF-QNM) reveals intact protein dimers on a mica surface.

冲红灯光感受器原子力显微镜使用PeakForce定量纳米机械性能映射

Atomic force microscopy (AFM) uses a pyramidal tip attached to a cantilever to probe the force response of a surface. The deflections of the tip can be ...

科研

工程学

Sub-nanometer Resolution Imaging with Amplitude-modulation Atomic Force Microscopy in Liquid

Atomic force microscopy (AFM) has become a well-established technique for nanoscale imaging of samples in air and in liquid. Recent studies have shown that when operated in amplitude-modulation (tapping) mode, atomic or molecular-level resolution images can be achieved over a wide range of soft and hard samples in liquid. In these situations, small oscillation amplitudes (SAM-AFM) enhance the resolution by exploiting the solvated liquid at the surface of the sample. Although the technique has been successfully applied across fields as diverse as materials science, biology and biophysics and surface chemistry, obtaining high-resolution images in liquid can still remain challenging for novice users. This is partly due to the large number of variables to control and optimize such as the choice of cantilever, the sample preparation, and the correct manipulation of the imaging parameters. Here, we present a protocol for achieving high-resolution images of hard and soft samples in fluid using SAM-AFM on a commercial instrument. Our goal is to provide a step-by-step practical guide to achieving high-resolution images, including the cleaning and preparation of the apparatus and the sample, the choice of cantilever and optimization of the imaging parameters. For each step, we explain the scientific rationale behind our choices to facilitate the adaptation of the methodology to every user's specific system.

We present a method for achieving sub-nanometer resolution images with amplitude-modulation (tapping mode) atomic force microscopy in liquid. The method is demonstrated on commercial atomic force microscopes. We explain the rationale behind our choices of parameters and suggest strategies for resolution optimization.

亚纳米级分辨率成像与调幅原子力显微镜在液体

Atomic force microscopy (AFM) has become a well-established technique for nanoscale imaging of samples in air and in liquid. Recent studies have shown ...

Production and Characterization of Vacuum Deposited Organic Light Emitting Diodes

A method for producing simple and efficient thermally-activated delayed fluorescence organic light-emitting diodes (OLEDs) based on guest-host or exciplex donor-acceptor emitters is presented. With a step-by-step procedure, readers will be able to repeat and produce OLED devices based on simple organic emitters. A patterning procedure allowing the creation of personalized indium tin oxide (ITO) shape is shown. This is followed by the evaporation of all layers, encapsulation and characterization of each individual device. The end goal is to present a procedure that will give the opportunity to repeat the information presented in cited publication but also using different compounds and structures in order to prepare efficient OLEDs.

A protocol for the production of simple structured organic light-emitting diodes (OLEDs) is presented.

真空沉积有机发光二极管的生产与表征

A method for producing simple and efficient thermally-activated delayed fluorescence organic light-emitting diodes (OLEDs) based on guest-host or exciplex ...

Generating Lap Joints Via Friction Stir Spot Welding on DP780 Steel

Friction stir spot welding (FSSW), a derivative of friction stir welding (FSW), is a solid-state welding technique that was developed in 1991. An industry application was found in the automotive industry in 2003 for the aluminum alloy that was used in the rear doors of automobiles. Friction stir spot welding is mostly used in Al alloys to create lap joints. The benefits of friction stir spot welding include a nearly 80% melting temperature that lowers the thermal deformation welds without splashing compared to resistance spot welding. Friction stir spot welding includes 3 steps: plunging, stirring, and retraction. In the present study, other materials including high strength steel are also used in the friction stir welding method to create joints. DP780, whose traditional welding process involves the use of resistance spot welding, is one of several high strength steel materials used in the automotive industry. In this paper, DP780 was used for friction stir spot welding, and its microstructure and microhardness were measured. The microstructure data showed that there was a fusion zone with fine grain and a heat effect zone with island martensite. The microhardness results indicated that the center zone exhibited a greater degree of hardness compared with the base metal. All data indicated that the friction stir spot welding used in dual phase steel 780 can create a good lap joint. In the future, friction stir spot welding can be used in high-strength steel welding applied in industrial manufacturing processes.

Here, we present a friction stir spot welding (FSSW) protocol on dual phase 780 steel. A tool pin with high-speed rotation generates heat from friction to soften the material, and then, the pin plunges into 2 sheet joints to create the lap joint.

通过 DP780 钢上的摩擦搅拌点焊生成圈接头

Friction stir spot welding (FSSW), a derivative of friction stir welding (FSW), is a solid-state welding technique that was developed in 1991. An industry ...

X-ray Beam Induced Current Measurements for Multi-Modal X-ray Microscopy of Solar Cells

X-ray beam induced current (XBIC) measurements allow mapping of&#160;the nanoscale performance of electronic devices such as solar cells. Ideally, XBIC is employed simultaneously with other techniques within a multi-modal X-ray microscopy approach. An example is given herein combining XBIC with X-ray fluorescence to enable point-by-point correlations of the electrical performance with chemical composition. For the highest signal-to-noise ratio in XBIC measurements, lock-in amplification plays a crucial role. By this approach, the X-ray beam is modulated by an optical chopper upstream of the sample. The modulated X-ray beam induced electrical signal is amplified and demodulated to the chopper frequency using a lock-in amplifier. By optimizing low-pass filter settings, modulation frequency, and amplification amplitudes, noise can efficiently be suppressed for the extraction of a clear XBIC signal. A similar setup can be used to measure the X-ray beam induced voltage (XBIV). Beyond standard XBIC/XBIV measurements, XBIC can be measured with bias light or bias voltage applied such that outdoor working conditions of solar cells can be reproduced during in-situ and operando measurements. Ultimately, the multi-modal and multi-dimensional evaluation of electronic devices at the nanoscale enables new insights into the complex dependencies between composition, structure, and performance, which is an important step towards solving the materials&#39; paradigm.

A setup for X-ray beam induced current measurements at synchrotron beamlines is described. It unveils the nanoscale performance of solar cells and extends the suite of techniques for multi-modal X-ray microscopy. From wiring to signal-to-noise optimization, it is shown how to perform state-of-the-art XBIC measurements at a hard X-ray microprobe.

太阳能电池多模态X射线显微镜的X射线光束诱导电流测量

X-ray beam induced current (XBIC) measurements allow mapping of&#160;the nanoscale performance of electronic devices such as solar cells. Ideally, XBIC is ...

Hydrogen Charging of Aluminum using Friction in Water

A new method of hydrogen charging of aluminum was developed by means of a friction in water (FW) procedure. This procedure can easily introduce high amounts of hydrogen into aluminum based on the chemical reaction between water and non-oxide coated aluminum.

In order to introduce high amounts of hydrogen in aluminum and aluminum alloys, a new method of hydrogen charging was developed, called the friction in water procedure.

利用水中摩擦力对铝进行氢充电

A new method of hydrogen charging of aluminum was developed by means of a friction in water (FW) procedure. This procedure can easily introduce high ...

Co-localizing Kelvin Probe Force Microscopy with Other Microscopies and Spectroscopies: Selected Applications in Corrosion Characterization of Alloys

Kelvin probe force microscopy (KPFM), sometimes referred to as surface potential microscopy, is the nanoscale version of the venerable scanning Kelvin probe, both of which measure the Volta potential difference (VPD) between an oscillating probe tip and a sample surface by applying a nulling voltage equal in magnitude but opposite in sign to the tip-sample potential difference. By scanning a conductive KPFM probe over a sample surface, nanoscale variations in surface topography and potential can be mapped, identifying likely anodic and cathodic regions, as well as quantifying the inherent material driving force for galvanic corrosion.
Subsequent co-localization of KPFM Volta potential maps with advanced scanning electron microscopy (SEM) techniques, including back scattered electron (BSE) images, energy dispersive spectroscopy (EDS) elemental composition maps, and electron backscattered diffraction (EBSD) inverse pole figures can provide further insight into structure-property-performance relationships. Here, the results of several studies co-localizing KPFM with SEM on a wide variety of alloys of technological interest are presented, demonstrating the utility of combining these techniques at the nanoscale to elucidate corrosion initiation and propagation.
Important points to consider and potential pitfalls to avoid in such investigations are also highlighted: in particular, probe calibration and the potential confounding effects on the measured VPDs of the testing environment and sample surface, including ambient humidity (i.e., adsorbed water), surface reactions/oxidation, and polishing debris or other contaminants. Additionally, an example is provided of co-localizing a third technique, scanning confocal Raman microscopy, to demonstrate the general applicability and utility of the co-localization method to provide further structural insight beyond that afforded by electron microscopy-based techniques.

Kelvin probe force microscopy (KPFM) measures surface topography and differences in surface potential, while scanning electron microscopy (SEM) and associated spectroscopies can elucidate surface morphology, composition, crystallinity, and crystallographic orientation. Accordingly, the co-localization of SEM with KPFM can provide insight into the effects of nanoscale composition and surface structure on corrosion.

开尔文探针力显微镜与其他显微镜和光谱学共定位：合金腐蚀表征中的选定应用

Kelvin probe force microscopy (KPFM), sometimes referred to as surface potential microscopy, is the nanoscale version of the venerable scanning Kelvin ...

Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains

Magnetic force microscopy (MFM) enables mapping local magnetic fields across a sample surface with nanoscale resolution. To perform MFM, an atomic force microscopy (AFM) probe whose tip has been magnetized vertically (i.e., perpendicular to the probe cantilever) is oscillated at a fixed height above the sample surface. The resultant shifts in the oscillation phase or frequency, which are proportional to the magnitude and sign of the vertical magnetic force gradient at each pixel location, are then tracked and mapped. Although the spatial resolution and sensitivity of the technique increases with decreasing lift height above the surface, this seemingly straightforward path to improved MFM images is complicated by considerations such as minimizing topographical artifacts due to shorter range van der Waals forces, increasing the oscillation amplitude to further improve sensitivity, and the presence of surface contaminants (in particular water due to humidity under ambient conditions). In addition, due to the orientation of the probe's magnetic dipole moment, MFM is intrinsically more sensitive to samples with an out-of-plane magnetization vector. Here, high-resolution topographical and magnetic phase images of single and bicomponent nanomagnet artificial spin-ice (ASI) arrays obtained in an inert (argon) atmosphere glovebox with &lt;0.1 ppm O2 and H2O are reported. Optimization of lift height and drive amplitude for high resolution and sensitivity while simultaneously avoiding the introduction of topographical artifacts is discussed, and detection of the stray magnetic fields emanating from either end of the nanoscale bar magnets (~250 nm long and &lt;100 nm wide) aligned in the plane of the ASI sample surface is shown. Likewise, using the example of a Ni-Mn-Ga magnetic shape memory alloy (MSMA), MFM is demonstrated in an inert atmosphere with magnetic phase sensitivity capable of resolving a series of adjacent magnetic domains each ~200 nm wide.

Magnetic force microscopy (MFM) employs a vertically magnetized atomic force microscopy probe to measure sample topography and local magnetic field strength with nanoscale resolution. Optimizing MFM spatial resolution and sensitivity requires balancing decreasing lift height against increasing drive (oscillation) amplitude, and benefits from operating in an inert atmosphere glovebox.

优化磁力显微镜分辨率和灵敏度，以可视化纳米级磁畴

Magnetic force microscopy (MFM) enables mapping local magnetic fields across a sample surface with nanoscale resolution. To perform MFM, an atomic force ...

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 ...

Determination of the Friction Coefficients of Icy Pavements Under Different Amounts of Snowfall

Ice on road surfaces can lead to a significant decrease in the friction coefficient, thus endangering driving safety. However, there are still no studies that provide exact friction coefficient values for pavements covered in ice, which is detrimental to both road design and the selection of winter road maintenance measures. Therefore, this article presents an experimental method to determine the friction coefficient of icy road surfaces in the winter. A British portable tester (BPT), also known as a pendulum friction coefficient meter, was employed for the experiment. The experiment was divided into the following five steps: the preparation of the equipment, the calculation and analysis of the snowfall, equipment calibration, friction coefficient determination, and data analysis. The accuracy of the final experiment is directly affected by the equipment accuracy, which is described in detail. Moreover, this article suggests a method for calculating the ice thickness for corresponding amounts of snowfall. The results illustrate that even patchy ice formed by very light snowfall may lead to a significant decrease in the friction coefficient of the pavement, thus endangering driving safety. Additionally, the friction coefficient is at its peak when the ice thickness reaches 5 mm, meaning protection measures should be taken to avoid the formation of such ice.

Here, we present a method for determining the friction coefficient of pavements with different ice thicknesses indoors. The complete procedure includes the preparation of the equipment, the calculation and analysis of the snowfall, equipment calibration, friction coefficient determination, and data analysis.

不同降雪量下结冰路面摩擦系数的测定

Ice on road surfaces can lead to a significant decrease in the friction coefficient, thus endangering driving safety. However, there are still no studies ...