Visualizing the Orientation of Single Polymers Induced by Spin-Coating

Abstract

The orientation of chains within polymeric materials influences their electrical, mechanical, and thermal properties. While many techniques can infer the orientation distribution of a bulk ensemble, it is challenging to determine this information at the single-chain level, particularly in an environment of otherwise identical polymers. Here, we use single-molecule localization microscopy (SMLM) to visualize the directions of chains within spin-coated polymer films. We find a strong relationship between shear force and the degree and direction of orientation, and additionally, we reveal the effects of chain length and solvent evaporation rate. This work utilizes single-chain resolution to observe the important, though often overlooked, property of chain orientation in the common fabrication process of spin-coating.

Structure–Reactivity–Property Relationships in Covalent Adaptable Networks

“…Significant advances in single-particle tracking and superresolution microscopy provide time-resolved, nano- to microscale insight into polymerization kinetics − and conformations of neat polymer chains. , We believe that the development of fluorescent probes that are responsive to dissociative bond formation/breaking or even associative, (quasi)-degenerate bond exchange would allow these optical techniques to be applied to CANs. The ability to map molecular events in time and space, as a function of applied deformations, will illuminate open questions in this field.…”

In situpost-synthesis of luminescent Lewis acid–base adducts

“…Basically, the solution dropped on the substrate is spun at a high speed to form the film by the centrifugal force and solvent evaporation. 3,4 The quality of the film depends on the solution system, the spin parameters such as spin-time, speed, atmosphere, and post treatments. [5][6][7] Once spin-coating starts, the solution covers the entire substrate quickly and the thickness of the deposited film cannot be tuned exactly.…”

Observation of Highly Anisotropic Thermal Expansion of Polymer Films

“…Thermal expansion and the associated thermal stress are the key material properties that dictate the reliability of heterogeneous polymer device applications, such as energy conversion, − organic thin-film sensors, − and semiconductor packaging. − In polymers, a thermal expansion coefficient is intimately connected with their microstructure, including the alignment of backbones and the interactions between neighboring side chains. − When the thickness of polymers becomes comparable to their gyration length scale, their microstructure is often found to be different from that of the bulk counterpart due to the disentanglement of polymer chains. , This rearrangement of the microstructures in the thin film limit potentially gives rise to anisotropic properties of polymers, as seen in previous studies for thermal conductivity, , electrical conductivity, , and mechanical properties. , However, experimental challenges as well as the absence of the microscopic model in understanding thermal expansion coefficients of nanoscale polymer films have led to an insufficient understanding of the origin of anisotropy.…”

“…For instance, between the spin casting and solution shearing process, shear stress is applied differently to the film leading to a variation of backbone chain alignment in polymer microstructure, thereby affecting the properties, as seen in electrical conductivity . Spin coating, a common thin-film processing, often induces anisotropic material behaviors . While many previous studies suggest that spin-coated films show anisotropic CTE depending on the fabrication parameters, these studies are limited to micron-scale-thick films.…”

“…25 Spin coating, a common thin-film processing, often induces anisotropic material behaviors. 13 While many previous studies suggest that spin-coated films show anisotropic CTE depending on the fabrication parameters, these studies are limited to micron-scale-thick films. In nanoscale films, the anisotropic nature of CTE can be drastically modified.…”