Engineering solvation in initiated chemical vapour deposition for control over polymerization kinetics and material properties

Chen, Pengyu; Zhang, Zheyuan; Rouse, Zach; Baker, Shefford P.; Yeo, Jingjie; Yang, Rong

doi:10.1038/s44160-023-00242-5

Cited by 4 publications

(13 citation statements)

References 52 publications

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“…As shown in Figure a, we confirmed that the deposition rate deviated from the linear correlation and remained at ∼3 nm/min under P M / P sat > 0.2. Furthermore, the apparent activation energy for the iCVD polymerization of 1VI has been reported to be −10 kJ/mol, whereas that for other iCVD monomers typically falls in the range of −60 to −160 kJ/mol , (Figure b). While the low deposition rate, distinct rate law, and high activation energy are unsurprising based on its unstable propagating radicals and a tendency to chain transfer, these side reactions are poorly understood in the context of CVD polymerization.…”

Section: Resultsmentioning

confidence: 99%

“…This difference in bonding nature had different impacts on iCVD polymerization kinetics (without changing other conditions) (Figure 2e). AcOH accelerated the deposition rate by 134%, whereas HFIP, known to form a molecular complex in the vapor phase, 16 accelerated the deposition rate by 38%. Isopropyl alcohol (IPA) and Ar demonstrated negligible effects on the polymerization kinetics.…”

Section: Inhibition Of Chain Transfer Via Vapor-phase Solvation Of 1v...mentioning

confidence: 99%

“…Despite the chemical versatility, side reactions during iCVD are poorly understood, with the important example of a class of nitrogen (N)-containing precursors, including N-vinyl monomers and methacrylate with an N-containing functional group. N-containing polymers have garnered special attention in the past decade due to their unique electron-rich structure and bioactivity, making them suitable for bioactive interfaces and antifouling coatings. , However, solution-based polymerization research has revealed that chain transfer could occur during the propagation of N-containing monomers, causing abnormal polymerization kinetics (with either accelerated or sluggish deposition) and limiting the molecular weight. − Taking 1-vinylimidazole (1VI) as an example, the propensity to chain transfer is rooted in the unstable electron-rich radicals that form upon activation (e.g., as manifested by the low Q-e values), , which tend to undergo chain transfer to form radicals stabilized by imidazole group. The imidazole-based radicals, as “dead” radicals, in turn, arrest propagation and limit the chain length. − A similar process occurs with an amine-containing monomer, except that it forms amine-based active free radicals .…”

Section: Introductionmentioning

confidence: 99%

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Curbing Chain Transfer in Initiated Chemical Vapor Deposition (iCVD) via Molecular Vapor Complexation

Chen,

Zhang,

Park

et al. 2024

Chem. Mater.

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Initiated chemical vapor deposition (iCVD) has revolutionized the preparation of high-quality conformal polymer films with excellent control over composition and properties at the nanoscale. It is compatible with over 70 functional monomers. Despite that chemical versatility, side reactions during iCVD are not well understood. For example, chain transfer could happen during the propagation of an important class of monomers that contain nitrogen (N), arresting the polymerization and limiting the molecular weight. Here, we use 1vinylimidazole (1VI) to demonstrate the chain transfer reaction to the imidazole group during iCVD, which leads to unpredictable deposition kinetics, low molecular weight, and undesirable products. We further introduce a strategy that utilizes a vapor solvent to engineer monomer reactivity and suppress side reactions. By replacing the traditional patch flow, Ar, with acetic acid (AcOH), which forms hydrogen bonding with 1VI, chain transfer is suppressed, and the deposition rate is increased by as much as 280% while restoring its linear dependence on the monomer partial pressure. That linear dependence has not been achieved previously for 1VI. The tunable deposition kinetics, in turn, leads to a broader range of attainable material properties, including nearly doubling the maximum attainable molecular weight (from 8 kDa to 16 kDa) and increasing the elastic modulus (from 3.5 to 4.7 GPa). The vapor solvent is also effective at suppressing chain transfer in other N-containing monomers, like (2-dimethylamine) ethyl methacrylate (DMAEMA), leading to a considerable increase in the molecular weight (from 16 kDa to 38 kDa). The vapor solvent selectively increases the reactivity of N-containing monomers during copolymerization, demonstrated using 1VI and divinylbenzene (DVB) or 1,3,5,7-tetravinyl tetramethylcyclotetrasiloxane (V4D4), increasing the reactivity ratio of 1VI by an order of magnitude according to the Fineman−Ross equation. This robust strategy engineers monomer reactivity without the need for chemical modifications. It improves the chemical precision of iCVD polymerization, particularly for an important class of N-containing monomers, which have found broad applications as the polymer− electrolyte interphase in batteries, antifouling coatings in food and water production, and bioactive and functionalizable coatings in sensors.

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Section: Resultsmentioning

confidence: 99%

Section: Inhibition Of Chain Transfer Via Vapor-phase Solvation Of 1v...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Curbing Chain Transfer in Initiated Chemical Vapor Deposition (iCVD) via Molecular Vapor Complexation

Chen,

Zhang,

Park

et al. 2024

Chem. Mater.

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“…Solvent-monomer vapor-phase complexation during the iCVD process can accelerate the growth rate, increase the upper bound on the molecular weight of the polymer chains, and facilitate morphological control of the film surface. [49] These effects are strongest for volatile solvents, which form hydrogen bonding complexes to polar iCVD monomers, such as AA or 4VP. Conversely, the growth rate was unchanged when HFIB was adding during the iCVD growth from the nonpolar, non-hydrogen bonding monomer DVB.…”

Section: Solvent-monomer Vapor-phase Complexationmentioning

confidence: 99%

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

Gleason

2023

Advanced Materials

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The initiated Chemical Vapor Deposition (iCVD) technique is an all‐dry method for designing organic and hybrid polymers. Unlike methods utilizing liquids or line‐of‐sight arrival, iCVD provides conformal surface modification over intricate geometries. Uniform, high‐purity, and pinhole‐free iCVD films can be grown with thicknesses ranging from > 15 μm to < 5 nm. The mild conditions permit damage‐free growth directly on to flexible substrates, 2D materials, and liquids. Novel iCVD polymer morphologies include nanostructured surfaces, nanoporosity, and shaped particles. The well‐established fundamentals of iCVD facilitate the systematic design and optimization of polymers and copolymers. The functional groups provide fine tuning of surface energy, surface charge, and responsive behavior. Further reactions of the functional groups in the polymers can yield either surface modification, compositional gradients through the layer thickness, or complete chemical conversion of the bulk film. The iCVD polymers have been integrated into multilayer device structures as desired for applications in sensing, electronics, optics, electrochemical energy storage, and biotechnology. For these devices, hybrids offer higher values of refractive index and dielectric constant. Multivinyl monomers typically produce ultrasmooth and pinhole‐free and mechanically deformable layers and robust interfaces which are especially promising for electronic skins and wearable optoelectronics.This article is protected by copyright. All rights reserved

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“…[19,20] The well-understood gas phase kinetics enable advanced ways to produce highly specific nanometer thin coatings like, e.g., gradient structures . [21,22] Only limited by the vacuum vapor phase behavior, the biocompatible polymers used in iCVD can be combined on demand and range from organosilicons [23,24] over hydrogels [25,26] to carbohydrates. [27] In iCVD especially hydrogels have successfully been used in bio-interface applications like advanced cell culture platforms, [28] for bone tissue engineering, [29] or as antifouling coatings.…”

Section: Introductionmentioning

confidence: 99%

iCVD Polymer Thin Film Bio‐Interface‐Performance for Fibroblasts, Cancer‐Cells, and Viruses Connected to Their Functional Groups and In Silico Studies

Hartig,

Mohamed,

Fattah

et al. 2023

Adv Materials Inter

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Thin polymer coatings are used to improve the interface between biological species and functional materials. Their interaction is significantly influenced by the functional groups and roughness of the polymer film and prediction of the interaction is thus of great interest. However, for conventional polymer films, this cannot be examined independently because of the interplay of defects, residual solvent molecules, roughness, and functional groups. Solvent‐free polymer films prepared by initiated chemical vapor deposition (iCVD) exhibit conformal, defect‐free characteristics and enable precise tailoring of the functional groups. This facilitates to isolate the contribution of functional groups on the bio‐interface performance. Consequently, in silico studies can enable a prediction of ligand interaction in anti‐viral activity for SARS‐CoV‐2 based on defined polymer and key protein structures. Furthermore, the cell viability of human fibroblasts can be traced back to the functional groups of the repeating units. For human liver cancer cell culture, it turns out that more sophisticated models are needed. The insilico‐iCVD approach can enable precise tailoring of complex polymer films optimized for the respective interfaces. In addition, this first big scan of the bio‐interface performance of iCVD films enables a solid starting point in areas like anticancer, antiviral, and biocompatibility for future studies.

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Engineering solvation in initiated chemical vapour deposition for control over polymerization kinetics and material properties

Cited by 4 publications

References 52 publications

Curbing Chain Transfer in Initiated Chemical Vapor Deposition (iCVD) via Molecular Vapor Complexation

Curbing Chain Transfer in Initiated Chemical Vapor Deposition (iCVD) via Molecular Vapor Complexation

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

iCVD Polymer Thin Film Bio‐Interface‐Performance for Fibroblasts, Cancer‐Cells, and Viruses Connected to Their Functional Groups and In Silico Studies

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