Controlling the Aspect Ratio of Supramolecular Fibers by Ultrasonication

Steinlein, Christoph; Kreger, Klaus; Schmidt, Hans‐Werner

doi:10.1002/mame.201900258

Cited by 4 publications

(6 citation statements)

References 41 publications

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“…Devices such as a vortex mixer and a sonication bath are commonly used in the laboratory but their impacts on the resulting architectures are rarely described. 25,86,87 In the case of kinetically controlled supramolecular polymerizations in particular, the sample preparation and history critically influences the supramolecular polymers observed. A rigorous description of the protocols used to prepare the samples seems essential to ensure a full comprehension of the systems studied.…”

Section: How To Experimentally Determine the Effect Of B On Supramolementioning

confidence: 99%

How to Determine the Role of an Additive on the Length of Supramolecular Polymers?

et al. 2020

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In polymer chemistry, modulation of sequence and control over chain length are routinely applied to alter and fine-tune the properties of covalent (co)polymers. For supramolecular polymers, the same principles underlying this control have not been fully elucidated up to this date. Particularly, rational control over molecular weight in dynamic supramolecular polymers is not trivial, especially when a cooperative mechanism is operative. We start this review by summarizing how molecular-weight control has been achieved in seminal examples in the field of supramolecular polymerizations. Following this, we propose to classify the avenues taken to control molecular weights in supramolecular polymerizations. We focus on dynamic cooperative supramolecular polymerization as this is the most challenging in terms of molecular weight control. We use a mass-balance equilibrium model to predict how the nature of the interaction of an additive B with the monomers and supramolecular polymers of component A affects the degree of aggregation and the degree of polymerization. We put forward a classification system that distinguishes between B acting as a chain capper, a sequestrator, a comonomer, or an intercalator. We also highlight the experimental methods applied to probe supramolecular polymerization processes, the type of information they provide in relation to molecular weight and degree of aggregation, and how this can be used to classify the role of B. The guidelines and classification delineated in this review to assess and control molecular weights in supramolecular polymers can serve to reevaluate exciting systems present in current literature and contribute to broaden the understanding of multicomponent systems.

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Section: How To Experimentally Determine the Effect Of B On Supramolementioning

confidence: 99%

How to Determine the Role of an Additive on the Length of Supramolecular Polymers?

et al. 2020

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“…Alternatively, a targeted size below 1 µm can be achieved by top- down strategies inducing strong shear forces. Typically, US is applied to fragment supramolecular structures [7,[30][31][32][33]. However, US causes cavitation within the sample, the collapse of which is accompanied by very high local heating.…”

Section: Resultsmentioning

confidence: 99%

Adjusting the length of supramolecular polymer bottlebrushes by top-down approaches

Klein¹,

Gruschwitz²,

Kuchenbrod³

et al. 2021

Beilstein J. Org. Chem.

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Controlling the length of one-dimensional (1D) polymer nanostructures remains a key challenge on the way toward the applications of these structures. Here, we demonstrate that top-down processing facilitates a straightforward adjustment of the length of polyethylene oxide (PEO)-based supramolecular polymer bottlebrushes (SPBs) in aqueous solutions. These cylindrical structures self-assemble via directional hydrogen bonds formed by benzenetrisurea (BTU) or benzenetrispeptide (BTP) motifs located within the hydrophobic core of the fiber. A slow transition from different organic solvents to water leads first to the formation of µm-long fibers, which can subsequently be fragmented by ultrasonication or dual asymmetric centrifugation. The latter allows for a better adjustment of applied shear stresses, and thus enables access to differently sized fragments depending on time and rotation rate. Extended sonication and scission analysis further allowed an estimation of tensile strengths of around 16 MPa for both the BTU and BTP systems. In combination with the high kinetic stability of these SPBs, the applied top-down methods represent an easily implementable technique toward 1D polymer nanostructures with an adjustable length in the range of interest for perspective biomedical applications.

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“…[17][18][19][20][21][22][23][24][25] In the last decade, the benzene trisamide (BTA) motif has become a focus point for multiple investigations. [26][27][28][29][30][31][32][33][34] It comprises a benzene core functionalized with three amide groups which allow individual modification with further pendant groups. The amide groups can form a triple helix of hydrogen bonds between stacked units and thus induce their aggregation into long columns.…”

Section: Introductionmentioning

confidence: 99%

Influence of Polymer Side Chain Size and Backbone Length on the Self‐Assembly of Supramolecular Polymer Bottlebrushes

Ulrich,

Gruschwitz,

Klein

et al. 2024

Chemistry A European J

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Hydrogen bonds are a versatile tool for creating fibrous, bottlebrush‐like assemblies of polymeric building blocks. However, a delicate balance of forces exists between the steric repulsion of the polymer chains and these directed supramolecular forces. In this work we have systematically investigated the influence of structural parameters of the attached polymers on the assembly behaviour of benzene trisurea (BTU) and benzene tris(phenylalanine) (BTP) conjugates in water. Polymers with increasing main chain lengths and different side chain sizes were prepared by reversible addition‐fragmentation chain‐transfer (RAFT) polymerization of hydroxyethyl acrylate (HEA), tri(ethylene glycol) methyl ether acrylate (TEGA) and oligo(ethylene glycol) methyl ether acrylate (OEGA). The resulting structures were analyzed using small angle X‐ray scattering (SAXS) and transmission electron microscopy (TEM). Both BTU and BTP formed fibres with PHEA attached, but a transition to spherical morphologies was observed at degrees of polymerisation (DP) of 70 and above. Overall, the main chain length appeared to be a dominating factor in inducing morphology transitions. Increasing the side chain size generally had a similar effect but mainly impeded any aggregation as is the case of POEGA. Interestingly, BTP conjugates still formed fibres, suggesting that the stronger intermolecular interactions can compensate partially for the steric repulsion.

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Controlling the Aspect Ratio of Supramolecular Fibers by Ultrasonication

Cited by 4 publications

References 41 publications

How to Determine the Role of an Additive on the Length of Supramolecular Polymers?

How to Determine the Role of an Additive on the Length of Supramolecular Polymers?

Adjusting the length of supramolecular polymer bottlebrushes by top-down approaches

Influence of Polymer Side Chain Size and Backbone Length on the Self‐Assembly of Supramolecular Polymer Bottlebrushes

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