Das Abhijna, Bolleddu Ravi, Singh Amit Kumar, Bandyopadhyay Dipankar
Department of Chemical Engineering, Indian Institute of Technology Guwahati, Assam 781039, India.
Centre for Nanotechnology, Indian Institute of Technology Guwahati, Assam 781039, India.
Nanotechnology. 2021 May 7;32(19):195303. doi: 10.1088/1361-6528/abe2c8.
Pathways to fabricate self-organized nanostructures have been identified exploiting the instabilities of ultrathin (<100 nm) polystyrene (PS) film on the polydimethylsiloxane (PDMS) substrates loaded with discrete and closely packed gold nanoparticles (AuNPs). The AuNPs were deposited on the PDMS substrates by chemical treatment, and the size and periodicity of the AuNPs were varied before coating the PS films. The study unveils that the physicochemical heterogeneity created by the AuNPs on the PDMS surface could guide the hole-formation, influence the average spacing between the holes formed at the initial dewetting stage, and affects the spacing and periodicity of the droplets formed at the end of the dewetting phase. The size and spacing of the holes and the droplets could be tuned by varying the nanoparticle loading on the PDMS substrate. Interestingly, as compared to the dewetting of PS films on the homogeneous PDMS surfaces, the AuNP guided dewetted patterns show ten-fold miniaturization, leading to the formation of the micro-holes and nanodroplets. The spacing between the droplets could also see a ten-fold reduction resulting in high-density random patterns on the PDMS substrate. Further, the use of a physicochemical substrate with varying density of physicochemical heterogeneities could impose a long-range order to the dewetted patterns to develop a gradient surface. The reported results can be of significance in the fabrication of high-density nanostructures exploiting the self-organized instabilities of thin polymers films.
利用负载离散且紧密排列的金纳米颗粒（AuNPs）的聚二甲基硅氧烷（PDMS）衬底上超薄（<100 nm）聚苯乙烯（PS）薄膜的不稳定性，已确定了制备自组织纳米结构的途径。通过化学处理将AuNPs沉积在PDMS衬底上，并在涂覆PS薄膜之前改变AuNPs的尺寸和周期性。该研究表明，AuNPs在PDMS表面产生的物理化学异质性可引导孔洞形成，影响初始去湿阶段形成的孔洞之间的平均间距，并影响去湿阶段结束时形成的液滴的间距和周期性。通过改变PDMS衬底上的纳米颗粒负载量，可以调节孔洞和液滴的尺寸和间距。有趣的是，与PS薄膜在均匀PDMS表面上的去湿相比，AuNP引导的去湿图案显示出十倍的小型化，导致微孔和纳米液滴的形成。液滴之间的间距也可以减少十倍，从而在PDMS衬底上形成高密度随机图案。此外，使用具有不同物理化学异质性密度的物理化学衬底可以对去湿图案施加长程有序，以形成梯度表面。报道的结果对于利用聚合物薄膜的自组织不稳定性制造高密度纳米结构可能具有重要意义。
