Batch-Operated Condensed Droplet Polymerization to Understand the Effect of Temperature on the Size Distribution of Polymer Nanodomes

Abstract

Size-controlled polymer nanodomes (PNDs) benefit a broad cross-section of existing and emerging technologies. Condensed droplet polymerization (CDP) is a vacuum-based synthesis technology that produces PNDs from monomer precursors in a single step. However, the effect of synthesis and processing conditions on the PND size distribution remains elusive. Towards size distribution control, we report the effect of substrate temperature, on which monomer droplets condense, on the size distribution of PNDs. We take a reductionist approach and operate the CDP under batch mode to match the conditions commonly used in condensation research. Notably, despite the rich knowledge base in dropwise condensation, the behavior of nonpolar liquids like a common monomer, i.e., 2-hydroxyethyl methacrylate (HEMA), is not well understood. We bridge that gap by demonstrating that dropwise condensation of HEMA follows a two-stage growth process. Early-stage growth is dominated by drop nucleation and growth, giving rise to relatively uniform sizes with a lognormal distribution, whereas late-stage growth is dominated by the combined effect of drop coalescence and renucleation, leading to a bimodal size distribution. This new framework for understanding the PND size distribution enables an unprecedented population of PNDs. Their controlled size distribution has the potential to enable programmable properties for emergent materials.

Designing Organic and Hybrid Surfaces and Devices with Initiated Chemical Vapor Deposition (iCVD)

“…Solid polymer nanodomes were fabricated by the novel method of condensed droplet polymerization (CDP) within an iCVD vacuum reactor (Figure 13A). [129,130] The CDP process requires only seconds to minutes to complete, significantly shorter than the multiple hours needed for traditional solution-based approaches for fabricating non-spherical particles. The versatility of the rapid, template-free, and solvent-free CDP technique was demonstrated for nine different iCVD polymers.…”

Significant Progress of Initiated Chemical Vapor Deposition in Manufacturing Soft Non-spherical Nanoparticles: Upgrading to the Condensed Droplet Polymerization Approach and Key Technological Aspects

“…In contrast, the two-step method of the nanodome formation process does not introduce the initiator simultaneously with the monomers during the first step [37]. The filament remains active throughout, with only the monomer vapor adsorbing on the substrate surface, depositing, nucleating, growing, and coalescing.…”

“…James [37] focused his research on analyzing the impact of solid substrate temperature (T s ) during CDP on the growth of monomer droplets and the distribution of particle sizes. While keeping the monomer partial pressure constant, he examined how PNDs are influenced by variations in T s .…”

“…Figure 6 depicts SEM images of the PNDs obtained on a pPFDA-coated substrate at temperatures of 21 • C, 24 • C, 27 • C, and 30 • C, with a scale bar of 200 nanometers [37]. From the comparison in the graph, it is evident that as the substrate temperature decreases, the final size of solidified nanodomes increases.…”