Hendeniya Nayanathara, Chittick Caden, Hillery Kaitlyn, Abtahi Shaghayegh, Mosher Curtis, Chang Boyce
Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, United States.
Roy J. Carver High-Resolution Microscopy Facility, Office of Biotechnology, Iowa State University, Ames, Iowa 50011, United States.
ACS Appl Mater Interfaces. 2024 Apr 10;16(14):18144-18153. doi: 10.1021/acsami.4c00076. Epub 2024 Mar 26.
Controlling the self-assembled morphologies in block copolymers heavily depends on their molecular architecture and processing conditions. Solvent vapor annealing is a versatile processive pathway to obtain highly periodic self-assemblies from high chi (χ) block copolymers (BCPs) and supramolecular BCP complexes. Despite the importance of navigating the energy landscape, controlled solvent vapor annealing (SVA) has not been investigated in BCP complexes, partly due to its intricate multicomponent nature. We introduce characteristic absorption-desorption solvent vapor isotherms as an effective way to understand swelling behavior and follow the morphological evolution of the polystyrene--poly(4-vinylpyridine) block copolymer complexed with pentadecylphenol (PS--P4VP(PDP)). Using the sorption isotherms, we identify the glass transition points, polymer-solvent interaction parameters, and bulk modulus. These parameters indicate that complexation completely screens the polymer interchain interactions. Furthermore, we established that the sorption isotherm of the homopolymer blocks serves to deconvolute the intricacy of BCP complexes. We applied our findings by developing annealing pathways for grain coarsening while preventing macroscopic film dewetting under SVA. Here, grain coarsening obeyed a power law and the growth exponent revealed a kinetic transition point for rapid self-assembly. Overall, SVA-based sorption isotherms have emerged as a critical method for understanding and developing annealing pathways for BCP complexes.
控制嵌段共聚物中的自组装形态在很大程度上取决于它们的分子结构和加工条件。溶剂蒸汽退火是一种通用的加工途径，可从高χ（χ）嵌段共聚物（BCP）和超分子BCP复合物中获得高度周期性的自组装体。尽管驾驭能量景观很重要，但在BCP复合物中尚未对可控溶剂蒸汽退火（SVA）进行研究，部分原因是其复杂的多组分性质。我们引入特征吸收-解吸溶剂蒸汽等温线，作为理解溶胀行为和跟踪与十五烷基苯酚复合的聚苯乙烯-聚（4-乙烯基吡啶）嵌段共聚物（PS-P4VP（PDP））形态演变的有效方法。利用吸附等温线，我们确定了玻璃化转变点、聚合物-溶剂相互作用参数和体积模量。这些参数表明络合作用完全屏蔽了聚合物链间相互作用。此外，我们确定均聚物嵌段的吸附等温线有助于解开BCP复合物的复杂性。我们通过开发在SVA下防止宏观膜去湿的同时使晶粒粗化的退火途径来应用我们的发现。在这里，晶粒粗化遵循幂律，生长指数揭示了快速自组装的动力学转变点。总体而言，基于SVA的吸附等温线已成为理解和开发BCP复合物退火途径的关键方法。
