A Critical Approach to Polymer Dynamics in Supramolecular Polymers

Abstract

Over the past few years, the concurrent (1) development of polymer synthesis and (2) introduction of new mathematical models for polymer dynamics have evolved the classical framework for polymer dynamics once established by Doi–Edwards/de Gennes. Although the analysis of supramolecular polymer dynamics based on linear rheology has improved a lot recently, there are a large number of insecurities behind the conclusions, which originate from the complexity of these novel systems. The interdependent effect of supramolecular entities (stickers) and chain dynamics can be overwhelming depending on the type and location of stickers as well as the architecture and chemistry of polymers. This Perspective illustrates these parameters and strives to determine what is still missing and has to be improved in the future works.

Dynamically tuning transient silicone polymer networks with hydrogen bonding

“…Supramolecular polymers have attracted enormous interest in recent years due to their dynamic nature and exceptional responsiveness to external stimuli. In these systems, transient noncovalent, physical interactions based on metal coordination, [1][2][3][4][5] hydrophobic interactions, [6][7][8] p-p stacking, 9 protein-protein interactions, 10 Lewis-acid Lewis-base interactions, 11 or hydrogen bonding [12][13][14][15][16] partially or fully replace covalent bonds between polymer chains. The network is non-permanent on experimental timescales because the physical crosslinks are in a permanent equilibrium between their associated and dissociated states; the location of the equilibrium can be influenced by the associative interaction strength, the molecular weight of the polymer, as well as by external parameters such as temperature and the application of shear.…”

Order–disorder transition in supramolecular polymer combs/brushes with polymeric side chains

“…1,2,[4][5][6][7][8]17 Although, in these works no comparative investigation was carried out to check the effect of the sticker on the self-assembly and comb/brush formation, extensive studies were done on the simpler cases of supramolecular polymers with sticky side-groups. [18][19][20][21][22][23][24][25] The side chain in all the above-mentioned supramolecular comb/brush polymers consists of either a small amphiphilic compound with a sticker at one end or in rare cases a polymer. Mono-functionalized polymers which form the side chains have been exclusively and widely studied in the framework of supramolecular telechelic polymers.…”

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

“…H bonds in the complex. Very often, however, the polarity of the H-bonding groups causes a natural energetic incompatibility between the groups and the polymer to which they are bound [14,17,18]. 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.…”

“…Their use is, however, limited related to the mixing of the components. The dynamics of supramolecular polymers in melt state was concisely reviewed [17]. In the bulk, the density of H-bonding groups is much higher than in solution, and therefore the chemical environment of the groups determines the group interactions in a decisive way.…”

“…In a more recent work, the apparently strongly preferred heterocomplementary thy-DAT association was applied to the formation of transient comb polymers based on PBO likewise directly in the bulk [40,41]. The study was highlighted in [17]. By a combination of SANS, rheology and broad-band dielectric spectroscopy, the mean lifetimes of the H-bonds in the bulk could be determined as being of the order of 1 s at −25 • C. From this result, a frequency of opening and closing on the order of~100 Hz at +25 • C was estimated.…”