Quasi‐Block Copolymers Based on a General Polymeric Chain Stopper

Sanguramath, Rajashekharayya A.; Nealey, Paul F.; Shenhar, Roy

doi:10.1002/chem.201600478

Cited by 7 publications

(8 citation statements)

References 55 publications

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“…52 To determine the presence of smaller aggregates such as dimers, trimers, or tetramers formed by sequestrators, solution diffusion ordered spectroscopy (DOSY) NMR techniques are feasible. 75,85 Different compounds or aggregates in a mixture are spectroscopically resolved depending on their diffusion coefficient D, size, and shape. Although the direct determination of length is often difficult with this technique, it can give many insights into the distribution of species formed in the presence of an additive.…”

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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“…In a number of studies, the chain-capper reported seems monofunctional (similar to the methodology in step-growth polymerizations) or has a very specific interaction with the end of the chain. 17−22…”

Section: Introductionmentioning

confidence: 99%

“…However, these strategies have not been applied to dynamic cooperative supramolecular polymerization under thermodynamic control. To steer polymer chain length in cooperative supramolecular polymerization, the term chain-stopper or end-capper has been used, − although it is not clear how this additive controls the length or deactivates the chain growth. Hence, this second component is not necessarily present at the end of the chain.…”

Section: Introductionmentioning

confidence: 99%

Tuning the Length of Cooperative Supramolecular Polymers under Thermodynamic Control

Vantomme¹,

Huurne²,

Kulkarni³

et al. 2019

J. Am. Chem. Soc.

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In the field of supramolecular (co)polymerizations, the ability to predict and control the composition and length of the supramolecular (co)polymers is a topic of great interest. In this work, we elucidate the mechanism that controls the polymer length in a two-component cooperative supramolecular polymerization and unveil the role of the second component in the system. We focus on the supramolecular copolymerization between two derivatives of benzene-1,3,5-tricarboxamide (BTA) monomers: a-BTA and Nle-BTA. As a single component, a-BTA cooperatively polymerizes into long supramolecular polymers, whereas Nle-BTA only forms dimers. By mixing a-BTA and Nle-BTA in different ratios, two-component systems are obtained, which are analyzed in-depth by combining spectroscopy and light-scattering techniques with theoretical modeling. The results show that the length of the supramolecular polymers formed by a-BTA is controlled by competitive sequestration of a-BTA monomers by Nle-BTA, while the obvious alternative Nle-BTA acts as a chain-capper is not operative. This sequestration of a-BTA leads to short, stable species coexisting with long cooperative aggregates. The analysis of the experimental data by theoretical modeling elucidates the thermodynamic parameters of the copolymerization, the distributions of the various species, and the composition and length of the supramolecular polymers at various mixing ratios of a-BTA and Nle-BTA. Moreover, the model was used to generalize our results and to predict the impact of adding a chain-capper or a competitor on the length of the cooperative supramolecular polymers under thermodynamic control. Overall, this work unveils comprehensive guidelines to master the nature of supramolecular (co)polymers and brings the field one step closer to applications.

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“…Knoben and others ,− have developed theoretical models to predict the impact of chain stoppers on the equilibrium length of supramolecular polymers formed in organic solvents. A modified form of Knoben’s model revealed that the equilibrium binding constant ( K a ) of TMPyP with TAP-CyCo6 is about 150 M –1 , a remarkably small valuein comparison, K a of TMPyP and G-quadruplex DNA is about 40 times greater. , The surface area of a TAP-CyCo6 hexad is approximately the same as that of TMPyP, which suggested that one TMPyP molecule binds at each fiber end, a prediction that was found to be fully consistent with the concentration of bound TMPyP and the concentration of polymer ends generated by TMPyP binding.…”

Section: Control Of Supramolecular Polymer Structure and Propertiesmentioning

confidence: 99%

Water-Soluble Supramolecular Polymers of Paired and Stacked Heterocycles: Assembly, Structure, Properties, and a Possible Path to Pre-RNA

et al. 2021

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The hypothesis that RNA and DNA are products of chemical and biological evolution has motivated our search for alternative nucleic acids that may have come earlier in the emergence of lifepolymers that possess a proclivity for covalent and non-covalent self-assembly not exhibited by RNA. Our investigations have revealed a small set of candidate ancestral nucleobases that self-assemble into hexameric rosettes that stack in water to form long, twisted, rigid supramolecular polymers. These structures exhibit properties that provide robust solutions to long-standing problems that have stymied the search for a prebiotic synthesis of nucleic acids. Moreover, their examination by experimental and computational methods provides insight into the chemical and physical principles that govern a particular class of water-soluble one-dimensional supramolecular polymers. In addition to efficient self-assembly, their lengths and polydispersity are modulated by a wide variety of positively charged, planar compounds; their assembly and disassembly are controlled over an exceedingly narrow pH range; they exhibit spontaneous breaking of symmetry; and homochirality emerges through non-covalent cross-linking during hydrogel formation. Some of these candidate ancestral nucleobases spontaneously form glycosidic bonds with ribose and other sugars, and, most significantly, functionalized forms of these heterocycles form supramolecular structures and covalent polymers under plausibly prebiotic conditions. This Perspective recounts a journey of discovery that continues to reveal attractive answers to questions concerning the origins of life and to uncover the principles that control the structure and properties of water-soluble supramolecular polymers.

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Quasi‐Block Copolymers Based on a General Polymeric Chain Stopper

Cited by 7 publications

References 55 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?

Tuning the Length of Cooperative Supramolecular Polymers under Thermodynamic Control

Water-Soluble Supramolecular Polymers of Paired and Stacked Heterocycles: Assembly, Structure, Properties, and a Possible Path to Pre-RNA

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