Department of Chemistry, University College Cork, Cork, Ireland.
Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin, Ireland.
Int J Mol Sci. 2009 Aug 25;10(9):3671-3712. doi: 10.3390/ijms10093671.
The thermodynamics of self-assembling systems are discussed in terms of the chemical interactions and the intermolecular forces between species. It is clear that there are both theoretical and practical limitations on the dimensions and the structural regularity of these systems. These considerations are made with reference to the microphase separation that occurs in block copolymer (BCP) systems. BCP systems self-assemble via a thermodynamic driven process where chemical dis-affinity between the blocks driving them part is balanced by a restorative force deriving from the chemical bond between the blocks. These systems are attracting much interest because of their possible role in nanoelectronic fabrication. This form of self-assembly can obtain highly regular nanopatterns in certain circumstances where the orientation and alignment of chemically distinct blocks can be guided through molecular interactions between the polymer and the surrounding interfaces. However, for this to be possible, great care must be taken to properly engineer the interactions between the surfaces and the polymer blocks. The optimum methods of structure directing are chemical pre-patterning (defining regions on the substrate of different chemistry) and graphoepitaxy (topographical alignment) but both centre on generating alignment through favourable chemical interactions. As in all self-assembling systems, the problems of defect formation must be considered and the origin of defects in these systems is explored. It is argued that in these nanostructures equilibrium defects are relatively few and largely originate from kinetic effects arising during film growth. Many defects also arise from the confinement of the systems when they are 'directed' by topography. The potential applications of these materials in electronics are discussed.
自组装系统的热力学是根据物种之间的化学相互作用和分子间力来讨论的。显然，这些系统的尺寸和结构规则都存在理论和实际的限制。这些考虑是针对嵌段共聚物 (BCP) 系统中发生的微相分离而做出的。BCP 系统通过热力学驱动过程自组装，其中块之间的化学不相容性驱动它们分离，而块之间的化学键则产生恢复力来平衡。这些系统因其在纳米电子制造中的潜在作用而引起了广泛的关注。在某些情况下，这种自组装形式可以获得高度规则的纳米图案，其中化学不同的块的取向和排列可以通过聚合物与周围界面之间的分子相互作用来引导。然而，要实现这一点，必须非常小心地正确设计表面与聚合物块之间的相互作用。最佳的结构导向方法是化学预图案化（定义衬底上不同化学性质的区域）和图形外延（形貌对准），但两者都集中在通过有利的化学相互作用产生对准上。与所有自组装系统一样，必须考虑缺陷形成的问题，并探讨这些系统中缺陷的起源。有人认为，在这些纳米结构中，平衡缺陷相对较少，主要源于薄膜生长过程中产生的动力学效应。许多缺陷还源于系统受到形貌限制时的限制。讨论了这些材料在电子学中的潜在应用。
