Molecular Approach to Supramolecular Polymer Assembly by Small Angle Neutron Scattering

Brás, Ana R.; Hövelmann, Claas H.; Antonius, Wiebke; Teixeira, J.; Rădulescu, Aurel; Allgaier, Jürgen; Pyckhout‐Hintzen, Wim; Wischnewski, A.; Richter, D.

doi:10.1021/ma401714r

Cited by 28 publications

(26 citation statements)

References 84 publications

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“…A truly disordered melt of individual chains with functional groups would only cause a correlation hole effect with a much weaker peak. This result excludes the prevalence of long, linear chain assemblies29, which otherwise could also lead to transient entanglements and a corresponding elastic plateau in the shear modulus. The fact that the peak position is nearly temperature independent indicates, that the mean distance between the aggregates or their number density stays the same over a broad range of temperatures.…”

Section: Resultsmentioning

confidence: 76%

Unveiling the molecular mechanism of self-healing in a telechelic, supramolecular polymer network

Yan

Schröter

Herbst

et al. 2016

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Reversible polymeric networks can show self-healing properties due to their ability to reassemble after application of stress and fracture, but typically the relation between equilibrium molecular dynamics and self-healing kinetics has been difficult to disentangle. Here we present a well-characterized, self-assembled bulk network based on supramolecular assemblies, that allows a clear distinction between chain dynamics and network relaxation. Small angle x-ray scattering and rheological measurements provide evidence for a structurally well-defined, dense network of interconnected aggregates giving mechanical strength to the material. Different from a covalent network, the dynamic character of the supramolecular bonds enables macroscopic flow on a longer time scale and the establishment of an equilibrium structure. A combination of linear and nonlinear rheological measurements clearly identifies the terminal relaxation process as being responsible for the process of self-healing.

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Section: Resultsmentioning

confidence: 76%

Unveiling the molecular mechanism of self-healing in a telechelic, supramolecular polymer network

Yan

Schröter

Herbst

et al. 2016

Sci Rep

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“…In small angle neutron scattering measurements (SANS) chain extended structures were observed in solution using polypropylene glycol functionalized with thymine and DAT units. 12 Using the comb architecture a complementary association would lead to the formation of a transiently branched structure, which combines e.g. the increased viscosity of branched polymer systems with the ex-ibility of the supramolecular association.…”

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confidence: 99%

Synthesis and rheological behavior of poly(1,2-butylene oxide) based supramolecular architectures

et al. 2016

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In this work we present the synthesis of poly(1,2-butylene oxide) (PBO) functionalized with the complementary hydrogen bond forming groups 2,4-diaminotriazine (DAT) and thymine. PBO is a rubbery polymer. Due to its semi-polar nature PBO is expected to suppresses non-directed cluster formation of the supramolecular groups but not influence their directed interactions. For the synthesis of backbone functionalized polymers we developed a procedure which allowed randomly copolymerizing BO with 1,2-epoxy-7-octene using anionic ring opening polymerization with potassium tert-butanolate as initiator. The vinyl groups were converted to OH-groups by oxidation. In addition, PBO with one alcoholic end group was obtained by homopolymerization of BO. For the variant with OH-groups at both chain ends a procedure was developed which was based on the cleavage of the tert-butyl initiator group. In all the polymers the alcohol groups were basically quantitatively transformed into NH 2 -groups.DAT and thymine functionalities were attached to the NH 2 -groups again in almost quantitative conversion. All reaction steps were monitored by 1 H-NMR using pyridine-d 5 as solvent. This method allowed determining the conversions of the different synthesis steps with high precision. The materials were examined in linear rheology in order to study the effect of the hydrogen-bonds on the dynamics of the resulting supramolecular structures. The results corroborate the exclusive existence of directed interactions between the supramolecular groups.

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“…Some comments regarding the sensitivity of calculation are important here: For the thy and DAT groups an average solubility parameter δ~24 is derived [27,34]. Referring to [34], the estimated δ parameter for PEO is 20.8, i.e., lower than the experimental literature value situated between 22 and 25 by roughly 2-3 MPa 1/2 [39].…”

Section: Structural Model Of Associationmentioning

confidence: 99%

“…They would tend to microphase separation or micellarization in the melt and introduce new time dependencies in their properties that are linked to the morphology and structure of hydrogen-bonding nanodomains, rather than to the H-bond itself. Many examples of such randomly or terminally functionalized polymers with hydrogen-bonding interactions in solution and bulk state can be found in the literature [11,13,[19][20][21][22][23][24][25][26][27]. In the present context, ionomers also structurally resemble the phase separation [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Supramolecular Dimerization in a Polymer Melt from Small-Angle X-ray Scattering and Rheology: A Miscible Model System

et al. 2020

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We present a structural and dynamic study on the simplest supramolecular hetero-association, recently investigated by the authors to prepare architectural homogeneous structures in the melt state, based on the bio-inspired hydrogen-bonding of thymine/diaminotriazine (thy–DAT) base-pairs. In the combination with an amorphous low Tg poly(butylene oxide) (PBO), no micellar structures are formed, which is expected for nonpolar polymers because of noncompatibility with the highly polar supramolecular groups. Instead, a clear polymer-like transient architecture is retrieved. This makes the heterocomplementary thy–DAT association an ideal candidate for further exploitation of the hydrogen-bonding ability in the bulk for self-healing purposes, damage management in rubbers or even the development of easily processable branched polymers with built-in plasticizer. In the present work, we investigate the temperature range from Tg + 20 °C to Tg + 150 °C of an oligomeric PBO using small-angle X-ray scattering (SAXS) and linear rheology on the pure thy and pure DAT monofunctionals and on an equimolar mixture of thy/DAT oligomers. The linear rheology performed at low temperature is found to correspond to fully closed-state dimeric configurations. At intermediate temperatures, SAXS probes the equilibrium between open and closed states of the thy–DAT mixtures. The temperature-dependent association constant in the full range between open and closed H-bonds and an enhancement of the monomeric friction coefficient due to the groups is obtained. The thy–DAT association in the melt is more stable than the DAT–DAT, whereas the thy–thy association seems to involve additional long-lived interactions.

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Molecular Approach to Supramolecular Polymer Assembly by Small Angle Neutron Scattering

Cited by 28 publications

References 84 publications

Unveiling the molecular mechanism of self-healing in a telechelic, supramolecular polymer network

Unveiling the molecular mechanism of self-healing in a telechelic, supramolecular polymer network

Synthesis and rheological behavior of poly(1,2-butylene oxide) based supramolecular architectures

Supramolecular Dimerization in a Polymer Melt from Small-Angle X-ray Scattering and Rheology: A Miscible Model System

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