Linear Alternating Associative Polymer with Ultrahigh Molecular Weight: Facile Preparation by Self-Assembly Assisted Dimerization of Anthracene and Rheology in Aqueous Solution

Abstract

Alternating associative polymers (AAPs) containing more than two species of alternating hydrophobic and hydrophilic units can form unique physical network and perform interesting rheological behavior in aqueous solution. In this work, an AAP was prepared through self-assembly assisted dimerization of an anthracene-functionalized telechelic associative polymer (AnTAP) in aqueous solution by light irradiation. It is demonstrated that AnTAP can in situ chain extend to AAP with well-defined linear structure and ultrahigh molecular weight through dimerization reaction of anthracene moieties in the core of micelle under light irradiation. Meanwhile, the solution changes from viscoelastic liquid to a free-standing gel, because a physical network that cannot relax in a finite time window has developed along with the dimerization process. The results are therefore of interest not only for understanding the network structure and rheological properties of AAP solution, but also for preparing AAPs with ultrahigh molecular weight by self-assembly assisted photodimerization reactions.

“Rod–coil” copolymers get self-assembled in solution

“…1). [140][141][142][143][144][145][146][147][148][149] Although the self-assembly of alternating copolymers remains much less explored compared with that of BCPs, it has attracted increasing attention in recent years due to their unique molecular architecture. For example, amphiphilic alternating copolymers generally have hydrophobic blocks of an equal length as well as the same length hydrophilic segments.…”

“…For example, amphiphilic alternating copolymers generally have hydrophobic blocks of an equal length as well as the same length hydrophilic segments. [144][145][146][147][148][149] These characteristics allow the self-assembly of alternating copolymers into nanostructures with hydrophobic or hydrophilic domains of uniform scale in spite of the molar mass dispersity of the copolymers. By taking advantage of this peculiarity, Ikeda and coworkers prepared 2D nanosheets with ultrathin and uniform thickness, which are generally hard to achieve by BCPs.…”

Aggregation and Rheology of a Triblock Supra-amphiphilic Polymer Prepared by Ionic Self-Assembly of a Double-Hydrophilic Polyelectrolyte with an Oppositely Charged Surfactant in Aqueous Solution

“…In aqueous solution, TAPs can spontaneously form flower-like micelles consisting of a hydrophobic core (terminal groups) and hydrophilic loop (backbone) above the critical micelle concentration ( cmc ). With further increases in the polymer concentration ( C ), the association among the micelles can take place through the bridging of some polymer chains, and micellar clusters even a physical cross-linking network can be formed when C exceeds the percolation concentration ( C p ). − The association is a dynamic process in which the hydrophobic terminal groups can integrate into and disengage from the micellar cores; thereby, the network structure can be destroyed and relax in a finite time, giving rise to an abundant rheological behavior such as Maxwellian linear viscoelasticity, , Newtonian plateau, , shear thickening, and shear thinning. ,, Up to now, numerous research efforts regarding TAPs have been devoted to the theoretical model, ,,, association mechanism , and the influence of polymer structures − on the viscoelasticity of the TAP solution. However, most conventional block amphiphilic polymers need complicated synthesis and purification processes.…”

Light-Induced In Situ Chain Extension and Critical Gelation of Benzophenone End-Functionalized Telechelic Associative Polymers in Aqueous Solution

“…Recently, some photosensitive groups such as coumarin and anthracene, which can undergo photoinduced dimerization reactions upon irradiation at a certain wavelength, have been introduced into the hydrophobic end groups of TAPs to tune the solution viscoelasticity through a self-assembly-assisted dimerization strategy. , Since the functionality ( f ) is 2 for these functionalized TAPs, linear alternating associative polymers containing multiple stickers are effectively and readily generated from these TAPs by in situ chain extension in terms of light-induced dimerization of photosensitive terminal groups in the micellar cores, so the solution dynamics is suppressed by multiple association junctions and more hydrophobic stickers. Meanwhile, a physical gel is developed.…”