这项工作已经由科学与工程，包括从化学系和研究办公室（RCAP 13-8032）内部支持的西肯塔基大学的奥格登学院的支持。约翰·Andersland博士在WKU显微镜基金（SEM图像）和WKU研究所燃烧科学与工程（BET分析）副曹燕教授的援助是中央对开展这项工作。

1.准备乳液<ol><li>乳液内容<ol><li>质量盐适量，以产生10个毫升0.03-M的溶液。对于铂（IV），氯化度量0.101克，为锌（II）氯化物（ 氯化锌 ）度量0.032克和氯化钠（NaCl）中测量0.018克。 </li><li>在个别试管，溶解每种盐于10ml DI水中。预留以备以后使用。 </li><li>使用一个20毫升，可密封的玻璃小瓶中的内容整个过程。去皮的平衡向玻璃小瓶。 </li><li>慢慢浇过来一个搅拌棒和成玻璃小瓶搁在归零衡称重乙烯基聚二甲基硅氧烷终止。称取1.02的克（相当于1.080毫升）。 注：该聚合物的高粘度，使移液不切实际。 </li><li>吸管1.02的毫升正庚烷的小瓶。添加2滴非离子表面活性剂（山梨糖醇单油酸酯）的小瓶中。吸管0.3 ml的盐溶液和0.45毫升去离子水的小瓶中。 </li><li>通过拧紧盖子上加以密封的玻璃小瓶。剧烈摇晃60秒开始超声之前启动乳液。 </li></ol></li><li>水，水浴超声设备建设<ol><li>填写超声仪加水至最低填充线。加入250毫升的自来水中以一个400毫升烧杯中。填补400毫升烧杯中在冰冷，使得水位刚好在轮辋。 </li><li>将此烧杯水浴超声波仪内。检查的超声发生器的填充线，如果需要调整。放置一个环站直接在水浴超声波仪旁边。 </li><li>使用两个环站箍，定位，使臂延伸出来，垂直于该环站和另一个延伸朝向水浴使其朝下放入盛有冰水的烧杯中。附加其他夹持到环站有温度计在400毫升烧杯中的向下，以使温度可以在整个超声处理进行监测。 </li></ol></li><li>乳化剂ication过程<ol><li>放置含乳剂样品瓶，以便它是由固定其插入夹具突出下入烧杯完全浸没在400毫升烧杯中。 </li><li>确保包含PDMS的混合物的玻璃小瓶未​​接触到烧杯的两侧，以消除因摩擦热。 </li><li>打开超声波仪和设置声波处理时间7分钟。因为该乳液是非常热敏感，确保该烧杯中的温度在0至5℃，在整个超声处理。启动超声处理一旦烧杯中的温度是理想的。 </li><li>后超声处理7分钟，取出小瓶并轻轻摇动/涡流1分钟，保持小瓶的顶部，以消除可能形成乳液的任何团块。 </li><li>处置的烧杯中的内容。重新注入250ml水，并填充冰加至在1厘米的烧杯的顶部。 </li><li>将小瓶放回钳。淹没它在冰水resumË超声7分钟。 </li><li>重复步骤1.3.3至1.3.6的总共八个，7分钟超声处理期间，或直到超声处理似乎是同质的并且没有团块存在。存储在RT。 注意：乳化应稳定数天，但通过超声处理如上述在7分钟的间隔，直到它出现均匀可以恢复。存储在RT。 </li></ol></li></ol> 2.交联<ol><li>设置为加三乙氧基硅烷/表面活性剂溶液<ol><li>吸管5.4 ml的三乙氧基硅烷置于试管。放置在通风橱中以备后用下一个试管架上。 </li><li>填写一个400毫升的烧杯中，用冰水，并放置在引擎盖下。旁边的400毫升烧杯中代替环站在附夹具，直接延伸在烧杯的开口。这将是冰浴中加入三乙氧基硅烷。 </li><li>放置在热板上在环形支架的另一侧。填写一个800毫升的烧杯中，用约700毫升自来水。将其放在加热板上。 </li><li>开启热板，保持75℃至85℃的800毫升烧杯内。附加的夹紧用温度计环形底座以800毫升烧杯内的水的温度可以被监控。 </li><li>产生通过将0.5克十二烷基硫酸钠375毫升水（4.62毫摩尔）的表面活性剂溶液。再加上约10毫升的表面活性剂溶液到一个干净的空试管中。 </li><li>附加其他夹持到环站与表面活性剂试管罩下固定，使得其液面为800毫升烧杯内的水的表面之下。允许10分钟的热平衡。 </li><li>湿一张滤纸，并将其放置在一个小漏斗的顶部。放置一个250ml的锥形烧瓶内漏斗的干，并放置在引擎盖下的烧瓶中。 </li></ol></li><li>另外三乙氧基硅烷<ol><li>放置乳液小瓶在钳位在冰水喙呃在罩内。在夹紧位置与PDMS混合物中，使小瓶内容是水的表面之下。加入三乙氧基硅烷导致放热反应，使该乳液必须保持冷，以保持其结构。 </li><li>从玻璃小瓶移除盖，以避免气体积聚。 </li><li>历时约10秒（大约0.5毫升/秒）慢慢倒入含有试管三乙氧基到玻璃小瓶中的连续流。 注意：除了三乙氧基硅烷开始放热反应，苛性氯化氢（HCl）气体的释放。小瓶会变得非常热，有毒气体将发展从混合物。不要搅拌的内容，同时增加了三乙氧基硅烷。 </li><li>完全加入三乙氧基硅烷后，轻轻搅拌用玻璃搅拌棒的内容，但戴防热手套。等待2分钟或直到气体停止从瓶中发展。 </li><li> FOLL由于交联，没有相分离的试样中可见。如果团块存在，密封小瓶，并摇晃严格，持续20秒，同时保持瓶的盖子。 </li></ol></li><li>珠生产<ol><li>使用干净的玻璃巴斯德吸管从玻璃小瓶绘制交联乳液。加交联的乳液滴至表面活性剂溶液（其应保持在75和85℃）放入试管以尽可能少的时间尽可能在液滴之间。 </li><li> 30秒到1在加入乳剂后分，表面活性剂溶液将开始慢慢演变气体作为固体开始形成的试管内。 </li><li>虽然穿着热防护手套，取试管出钳，其全部内容倒在引擎盖下的过滤装置。过滤5分钟。从过滤器中取出滤纸。 </li><li>下的H传输滤出的固体上表玻璃和单独的珠O / N干燥洪水。珠清洁可无限期推迟。商店干燥珠在室温在密封的玻璃小瓶中直到需要，清洁前立即使用。 </li></ol></li><li>珠清洗<ol><li>创建罩下另过滤装置，并放置在漏斗内的干燥珠在滤纸的上面。 </li><li>用塑料洗瓶装满离子水冲洗珠轻轻的，移动起来稍微，以确保所有的珠子冲洗。 </li><li>让珠通过将它们放置在引擎盖下表玻璃干燥1小时。使用的洗涤瓶填充用己烷冲洗使用相同的方法的珠用水漂洗。 </li><li>将珠子上的表玻璃。放置皿，在引擎盖下的珠粒干燥。 </li><li>后珠粒完全干燥后，将它们放置在一个小的可密封的玻璃小瓶中并储存在室温下供将来使用。 </li></ol></li><li>安装珠的SEM分析SEM设置<ol><li>将做一个带在其上的珠子会被安装在短线的顶部uble双面碳导电胶带。用剪刀修剪周围的存根，以确保没有带笼罩着边缘。 </li><li>放置存根下一张滤纸在一个平面上。从带去除顶层，使得粘合剂底面露出。 </li><li>轻轻倒入珠在存根。有些珠将坚持到磁带上，但大多数人会弹开和土地在滤纸上。倾这些放回小瓶如果他们停留在滤纸上。必要时重复进行，任何清洗珠（根据2.4.2至2.4.5），其被污染。 </li><li>为确保珠的存根安全，使用球形注射器轻轻密切吹存根表面。在存根倾多珠如果只有几个粘到带上。确保所有的珠子都将存根到SEM室和疏散前的安全。 </li><li>一旦样品已安装正确，他们现在已经准备好进行SEM肛门ysis 15。在低洼VAC模式的图像在15千电子伏，优化的珠的表面特征的分辨率。 </li></ol></li></ol>

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The authors have nothing to disclose.

使用此协议（以及通过调节电解质浓度和同一性）中产生的小珠与那些用低离子强度的乳液产生根本的不同，所看到的图1A的比较的其他SEM图像在图1中。我们最初的报告中使用PTCL 4的进一步催化聚合交联在水性脂族接口 14的意图。在该报告中，大凹压痕进行观察。由于该报告中，我们已经改进我们的程序来优化SAV的比例。无需水洗珠，扫描电镜图像中域?...

Polydimethylsiloxane (PDMS) is one of the most widely used silicone compounds. Its biocompatibility has led to widespread use in implant and other biomedical engineering structures1,2. It is trivially cross-linked into elastic structures using an organosilyl compound (such as triethoxysilane), a simple and reliable procedure which has made it useful for cast polymer applications where some flexibility is required3. Once cross-linked, PDMS is largely inert, particularly in biological conditions, and is therefore useful for a variety of food and medical applications4,5. Ease of casting, chemical inertness, and hydrophobicity have made it a natural choice for microfluidic devices6,7. Its affinity for non-halogenated, non-polar organic compounds has made it a popular stationary phase in separations chemistry8-10. 
Recently, microbubble fabrications have been used to generate porous beads for use as catalyst structural substrates or in chemical separations11,12. In both applications, ideal materials will have a maximized surface-area-to-volume (SAV) ratio for best efficiency. In a microbubble fabrication process, microstructuring of materials is typically accomplished by isolating the polymer in aliphatic &#8220;microbubbles&#8221; by emulsification in an aqueous continuous phase. The initial report of microporous PDMS beads produced them by mechanical emulsification of two phases (aliphatic and aqueous)13. The stock PDMS liquid (and its cross-linking agent) is dissolved into the aliphatic phase, which is structured into microscopic beads by being forced to cavitate within the (continuous) aqueous phase. The emulsification is stabilized by the addition of a non-ionic surfactant. When the emulsion is added dropwise to a heated bath, solid beads form by agglomeration of the microbubbles into clusters of tiny spheres of cross-linked PDMS. Our goal in this protocol is to modify this procedure to develop beads with an inverted porosity to improve the SAV ratio of the material.
As reported previously, control of the beads can be directed to some extent by the aliphatic:aqueous ratios in the emulsion. However, we have reported recently that addition of platinum(IV) chloride (PtCl4) inverts the porosity: materials are formed in which the PDMS is riddled with concave pores14. This indicates that the aqueous layer cavitates inside the aliphatic one, despite having similar aliphatic:aqueous ratios to those published in the original work13. The primary advantage of our method is that this concave porosity should naturally result in an increased SAV ratio, and thus, improved efficiency for analytical chemistry applications. While we are continuing to explore the specific effects of the addition of the platinum compound, we show here that the same effect can be accomplished using any aqueously soluble ionic compound, though perhaps to a reduced extent. Because our techniques also differ in some key aspects from what has been previously reported, we present our protocols here as a video to encourage others to extend our methods. Most notably, we use a common bath sonicator of the type used to clean glassware or other equipment, rather than the (considerably more expensive) probe sonicator often used in microbubble fabrication. This adjusted approach to the microbubble fabrication procedure could potentially be extended for the production of large quantities of bulk materials as well, creating porous sheets or slabs which could have applications for biomedical devices, aerospace and automotive industry, or substrates for chemical catalysis. Users seeking to generate high-SAV-ratio, microstructured materials using other similar polymers for such analyses may find that our protocols can be extended to any polymer for which the microbubble emulsion technique can be applied.

<table border="0">
	<tbody>
		<tr>
			<td>Poly(dimethylsiloxane), vinyl terminated</td>
			<td>Sigma-Aldrich</td>
			<td>68083-19-2</td>
			<td></td>
		</tr>
		<tr>
			<td>n-Heptane</td>
			<td>Sigma-Aldrich</td>
			<td>142-82-5</td>
			<td>Flammable</td>
		</tr>
		<tr>
			<td>Triethoxysilane</td>
			<td>Sigma-Aldrich</td>
			<td>998-30-1</td>
			<td>Flammable, Accutely Toxic</td>
		</tr>
		<tr>
			<td>Sorbitan Monoleate (Span-80)</td>
			<td>Fluker</td>
			<td>1338-43-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Platinum (IV) Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>13454-96-1</td>
			<td>Accutely Toxic</td>
		</tr>
		<tr>
			<td>Zinc (II) Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>7646-85-7</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>7647-14-5</td>
			<td></td>
		</tr>
		<tr>
			<td>2.8L Water Bath Sonicator</td>
			<td>VWR</td>
			<td>97043-964</td>
			<td></td>
		</tr>
	</tbody>
</table>

microbubble fabrication of concave-porosity pdms beads

Microbubble fabrication (by use of a fine emulsion) provides a means of increasing the surface-area-to-volume (SAV) ratio of polymer materials, which is particularly useful for separations applications. Porous polydimethylsiloxane (PDMS) beads can be produced by heat-curing such an emulsion, allowing the interface between the aqueous and aliphatic phases to mold the morphology of the polymer. In the procedures described here, both polymer and crosslinker (triethoxysilane) are sonicated together in a cold-bath sonicator. Following a period of cross-linking, emulsions are added dropwise to a hot surfactant solution, allowing the aqueous phase of the emulsion to separate, and forming porous polymer beads. We demonstrate that this method can be tuned, and the SAV ratio optimized, by adjusting the electrolyte content of the aqueous phase in the emulsion. Beads produced in this way are imaged with scanning electron microscopy, and representative SAV ratios are determined using Brunauer&#8211;Emmett&#8211;Teller (BET) analysis. Considerable variability with the electrolyte identity is observed, but the general trend is consistent: there is a maximum in SAV obtained at a specific concentration, after which porosity decreases markedly.

从乳液具有不同的电解质条件所引起珠的代表性SEM图像示于图1。图1A示出类似于由DuFaud获得， 等人 13的胎圈，制作使用我们的程序，不加入任何的电解质。 如图1B-D珠，从而导致不同的形态为每个金属离子。对于所示的所有图像，300微升0.03-M的电解质溶液代替300微升去离子水中的水相，使用，得到0.012 M在该相中的电解质浓度。更高分辨率的图像示于的无电...

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Microbubble Fabrication of Concave-porosity PDMS Beads

Procedures used to generate microstructured concave-porosity polydimethylsiloxane beads are presented. Effects of electrolyte concentration and identity within the aqueous phase are particularly emphasized.

的凹孔隙PDMS珠微泡制作

Microbubble fabrication (by use of a fine emulsion) provides a means of increasing the surface-area-to-volume (SAV) ratio of polymer materials, which is ...

microbubble-fabrication-of-concave-porosity-pdms-beads

Research

JoVE Journal

Chemistry

8.2K 次观看.  Western Kentucky University. Procedures used to generate microstructured concave-porosity polydimethylsiloxane beads are presented. Effects of electrolyte concentration and identity within the aqueous phase are particularly emphasized. 