Materials World Network: Electrochemical Processing of Nanoporous Structures for Superhydrophobic Materials and Polymer Imprinting

这项与南澳大利亚大学(UniSA)合作的项目旨在设计和评估孔径和表面粗糙度可控的纳米多孔金属(NPM)结构的性能。基于二元合金去合金化和/或电位控制电偶置换(PCD)的电化学处理将被用来产生横向长度在5纳米到几微米范围内的坚固的、表面受限的多孔层。随后对这些膜进行表面修饰(例如，单分子膜的自组装、硅烷化学吸附、等离子体聚合物沉积)将使这些衬底变得超疏水。这种改性结构具有高度压低的粘附性，因此具有显著的耐化学性。此外，几乎不存在的接触角滞后有助于水滴在小倾角时很容易地从超疏水表面滚下来。这一建议的另一个方向强调旨在开发从限制在薄表面层中的NPM结构制造聚合物印迹的可行程序的研究。超疏水NPM及其聚合物复制品的潜在应用包括自清洁窗户、防雪卫星天线、减少摩擦的管道和防雨输电线路。美国同行在这一合作倡议中的目标主要集中在开发用于合成纳米孔铜、银、金、钯和铂的协议，其结果如下：(I)探索在铜-金和铜-铂(一组分溶解)和锌-铜和铜-钯(两组分溶解)合金脱合金过程中控制孔尺寸的可调参数的基础研究；(Ii)对铜-银(不混溶)和铜-金(可混溶)体系的相变过程进行了基础性研究，重点研究了控制表面形态演变的因素。主要的科学成果将通过完成脱合金和PCD工艺的比较研究来体现，目的是从控制因素和由此产生的表面形态来确定相似和不同之处。虽然合金加工将主要通过经典的电化学方法进行，但合成的NPM的结构、形貌和表面成分将使用扫描电子显微镜(SEM)、扫描探针显微镜(SPM)、小角中子散射(SANS)和X射线光电子能谱(XPS)进行表征。研究活动(由澳大利亚研究理事会共同资助)安排在与澳大利亚大学合作开发的三个强连接模块中：(I)基础研究和开发合成NPM的最佳电化学途径，(Ii)探索和实施有效的NPM表面疏水策略，以及(Iii)开发复制NPM表面形貌的聚合物印迹的制造方法。该奖项将支持那些将在暑期与对应学院的学生交换活动中接触到国际研究环境的研究生。该奖项由美国国家科学基金会国际科学与工程办公室的东亚-太平洋项目和材料研究部的金属和固体化学项目共同支持。

The collaborative program with University of South Australia (UniSA) is aimed at designing and assessing the properties of nanoporous metal (NPM) architectures with controllable pore size and surface roughness. Electrochemical processing based on de-alloying of binary alloys and/or potential controlled galvanic displacement (PCD) will be employed to produce robust, surface-confined porous layers with lateral length-scales in the range of 5 nm to several microns. A subsequent surface modification of these layers (e.g. self-assembly of monolayers, silane chemisorption, plasma polymer deposition) will render these substrates superhydrophobic. Modified structures of that kind possess highly depressed adhesion properties and hence a significant chemical resistance. Also, the virtually non-existing contact angle hysteresis helps water droplets to easily roll off the superhybrophobic surface at small tilting angles. Another direction of this proposal emphasizes research aimed at developing of viable procedure for making polymer imprints from NPM structures confined in a thin surface layer. Potential applications of superhydrophobic NPM and their polymer replicas include self-cleaning windows, snow-repelling satellite antenna, pipes with reduced friction and rain-resistant transmission lines.The objectives of the American counterpart in this collaborative initiative are primarily focused on the development of protocols for synthesis of nanoporous Cu, Ag, Au, Pd and Pt, based on results of: (i) a fundamental study exploring tunable parameters that control the pore size during de-alloying in Cu-Au and Cu-Pt (one component dissolves) and Zn-Cu and Cu-Pd (both components dissolve) alloys; (ii) a fundamental investigation of the PCD process in Cu-Ag (immiscible) and Cu-Au (miscible) systems with emphasis on the factors controlling the evolution of surface morphology. The main scientific outcome will be manifested by the accomplishment of a comparative study of de-alloying and PCD processes aimed at identifying similarities and differences in view of controlling factors and resulting surface morphology. While the alloy processing will be carried out mainly by classical electrochemical methods, the structure, morphology and surface composition of the synthesized NPM will be characterized using scanning electron microscopy (SEM), scanning probe microscopy (SPM), Small Angle Neutron Scattering (SANS) and X-ray Photoelectron Spectroscopy (XPS)The research activity (co-funded by the Australian Research Council) is arranged in three strongly connected modules developed in collaboration with UniSA: (i) Fundamental investigation and development of optimal electrochemical pathways for synthesis of NPM, (ii) Exploration and implementation of efficient strategies for the hydrophobization of the NPM surfaces, and (iii) Development of procedures for fabricating polymer imprints that replicate the NPM surface topography. The award will support graduate students who will be exposed to an international research environment in summer-long student exchange initiatives with the counterpart institution.This award is co-supported by East Asia-Pacific Program of the NSF Office of International Science and Engineering, and by the Metals and Solid State Chemistry Programs of the Division of Materials Research.