大面积的制造自立性的超薄聚合物薄膜
Summary
We describe a method for the fabrication of large-area (up to 13 cm diameter) and ultrathin (as thin as 8 nm) polymer films. Instead of using a sacrificial interlayer to delaminate the film from its substrate, we use a self-limiting surface treatment suitable for arbitrarily large areas.
Abstract
This procedure describes a method for the fabrication of large-area and ultrathin free-standing polymer films. Typically, ultrathin films are prepared using either sacrificial layers, which may damage the film or affect its mechanical properties, or they are made on freshly cleaved mica, a substrate that is difficult to scale. Further, the size of ultrathin film is typically limited to a few square millimeters. In this method, we modify a surface with a polyelectrolyte that alters the strength of adhesion between polymer and deposition substrate. The polyelectrolyte can be shown to remain on the wafer using spectroscopy, and a treated wafer can be used to produce multiple films, indicating that at best minimal amounts of the polyelectrolyte are added to the film. The process has thus far been shown to be limited in scalability only by the size of the coating equipment, and is expected to be readily scalable to industrial processes. In this study, the protocol for making the solutions, preparing the deposition surface, and producing the films is described.
Introduction
自由站立薄聚合物膜被用在各种应用，包括传感器，1-3的MEMs，催化或过滤，4和组织工程。5-8它们还用于基础研究探索聚合物在封闭条件下的行为。9- 13所述的自立式膜是一个支撑在非连续基底例如环形环或环箍相对于在硅晶片或玻璃载玻片。这项工作描述了一个简单的，可重复的制造过程为超薄的自立聚合物膜，是适合于大面积膜或高通量的生产。它是一种具有多种不同的聚合物，包括聚（乙烯醇缩甲醛），聚苯乙烯，和聚（甲基丙烯酸甲酯）的兼容。它可被用于制造自支撑膜是一样大的13厘米直径或薄10纳米。
的自由站立的聚合物的制造包括三个基本步骤：1）D聚合物膜的eposition到传统衬底诸如晶片或幻灯片，2） 释放或从基材膜的剥离 ，和3） 捕获得到的膜的到载体上。本文详细介绍了我们在报道的各种版本方法的早期研究的过程。14
沉积可通过任何数目的基本聚合物薄膜的技术，如旋涂，蒸镀，或浸涂来实现。在这项工作中，我们采用标准的旋涂技术。
的“剥离浮于”技术是最常用的方法，用于从它的基底释放超薄膜15在这种技术中，薄膜和基板浸在适当的溶剂浴中。溶剂溶胀的膜和诱导自发分层，释放膜并使其漂浮到浴的顶部。最小膜厚度可使用提起被释放断开浮筒上通过与膨胀引起的应变能平衡界面剥离能量确定：16
（1）
其中，L是膜厚度，νf是薄膜的泊松比，E是杨氏模量的膜，ξ为膜的溶胀比，和γ是剥离的界面能。的典型方式绕过由公式所施加的限制（1）是沉积膜和淀积衬底之间的牺牲层间17-20当此夹层溶解在溶剂浴，膜被释放，并且可以在支撑被捕获。一个相关的方法是牺牲覆盖层的方法，它利用膜的机械剥离到牺牲层PRIOR溶解。21
使用牺牲材料的有几个主要缺点。首先，增加了一个额外的处理材料和步骤，可能需要最佳膜制造条件和牺牲材料的加工条件之间的折衷。第二，牺牲材料可能难以存在不影响机械性能的最终自立式膜的或纯度。第三，该方法用于沉积牺牲材料必须优化并监测质量在整体自立式膜制造的操作。14
在这项工作中，我们描述了一种表面改性技术，降低了界面剥离能量，使剥离浮于技术用于超薄膜。淀积衬底通过组装一个自限，自优化近单层的聚阳离子polydiallyldiammonium氯（PDAC）改性。由于聚阳离子和基片之间的结合强度，该表面改性是稳健的后续工艺步骤。近单层形成的自我限制和自我优化性质要求几乎为零优化是容易扩展到大面积。
以下的去除，该膜浮到溶剂浴的顶部，其中它被捕获在环箍状支撑。尽管不十分重视在现存文献，在这项工作中，我们将描述用于捕获大面积薄膜在载体上，以减少撕裂或以其他方式损坏膜的概率技术。
Protocol
Representative Results
Discussion
在PDAC基板处理是基于自限静电相互作用，这意味着任何尺寸的基板可以容易地处理过的，只要它们是带负电荷的（ 例如 ，硅或玻璃）。 图1-2显示了非常大的薄膜（13厘米在直径）制造使用此协议，唯一的变化是所用的试剂的体积。最终达到的尺寸出现仅由沉积和剥离设备或用于制造自支撑结构的聚合物的最终强度的限制。而前者显然是一个实际的问题，后者不是的聚合物的?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
根据合同DE-AC52-07NA27344美国能源署的主持下进行的由劳伦斯·利弗莫尔国家实验室的这项工作。
Materials
| Vinylec E | SPI | ||
| ethyl lactate, >98%, FCC, FG, | Sigma-Aldrich | W244007-1KG-K | |
| 4" silicon wafers <100>, Single side polished | International Wafer Service | ||
| sulfuric acid, 98%, ACS reagent grade | Sigma-Aldrich | 320501-6X500ML | |
| hydrogen peroxide, 30%, semiconductor grade | Sigma-Aldrich | 316989-3.7L | |
| isopropanol, ACS grade, 4 L | Fisher Scientific | A464-4 | |
| dichloromethane, ACS grade | Alfa-Aesar | 22917 | |
| deionized water , distilled | |||
| PDAC reagent (Sigma-Aldrich 409014) | Sigma-Aldrich | 409014 | |
| Spin Coater | Laurell Technologies | WS-650-23 | |
| Barnstead/Thermolyne Super Nuova explosion-proof hot plate | |||
| explosion-proof forced air oven | VWR | 1330 FMS | |
| balance with a range of 1 mg to 1020 g | Mettler Toledo | MS1003S | |
| reflectance spectrometer | Filmetrics | F20-UV | |
| manipulator consisting of a Klinger tilt stage, a Brinkman rack-and-pinion and a lab jack | |||
| Cutting tool/template, LLNL-built, no drawings | |||
| straight edge, LLNL, no drawings | |||
| Tent hoop, LLNL | |||
| culture dish 190 mm x 100 mm, Pyrex | VWR | ||
| 20 ml beaker, Pyrex | VWR | ||
| 250 ml beaker, Pyrex | VWR | ||
| 1000 ml beaker, Pyrex | VWR | ||
| 60 ml glass vial with plastic stopper | VWR | ||
| petri dish, 150 mm diameter x2, Pyrex | VWR | ||
| 600 ml beaker x2, Pyrex | VWR | ||
| tweezers, stainless steel | |||
| cutting blade | Exacto | ||
| clean room wipes | Contec | PNHS-99 | |
| polyester knit 9/91 IPA/DI water wipes | Contec | Prosat | |
| Fluoroware wafer trays | Ted Pella | 1395-40 | |
| Nylon Micro fiber (camel hair) | |||
| Disposable BD 3-mL plastic syringe | VWR | ||
| 0.2 um Luer-lock PTFE filters | Acrodisc | ||
| 0.45 um Luer-lock PTFE filters | Acrodisc |
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