The self-assembly of a novel double hydrophilic block copolymer (DHBC) architecture is presented. By combining linear biomacromolecule pullulan with biocompatible poly(oligo(ethylene glycol) methyl ether) methacrylate) (P(OEGMA))-brush blocks via copper(I) catalyzed azide alkyne cycloaddition, a novel DHBC linear-brush combination is obtained. Self-assembly in water was observed via optical microscopy and dynamic light scattering (DLS). Moreover, DLS investigations showed that self-assembly efficiency significantly relies on the degree of polymerization of the brush-block. Furthermore, the self-assembly of the formed particles was investigated with cryogenic scanning electron microscopy (cryo-SEM). To preserve the aggregates at lower concentrations, a biocompatible and FDA approved cross-linking agent, namely, sodium trimetaphosphate (STMP), was utilized for cross-linking. The reaction of STMP and pullulan was followed by P NMR, while the presence of the cross-linking agent within the particles could be detected via the combination cryo-SEM and energy dispersive X-ray spectroscopy.

Supramolecular hydrogels play a prominent role in contemporary research of hydrophilic polymers. Especially, hydrogels based on α-cyclodextrin/poly(ethylene glycol) (α-CD/PEG) complexation and crystal formation are studied frequently. Here, the effect of double hydrophilic block copolymers (DHBCs) on α-CD/PEG hydrogel properties is investigated. Therefore, a novel DHBC, namely poly( N -vinylpyrrolidone)- b -poly(oligo ethylene glycol methacrylate) (PVP- b -POEGMA), was synthesized via a combination of reversible deactivation radical polymerization and modular conjugation methods. In the next step, hydrogel formation was studied after α-CD addition. Interestingly, DHBC-based hydrogels showed a significant response to thermal history. Heating of the gels to different temperatures led to different mechanical properties after cooling to ambient temperature, i.e., gels with mechanical properties similar to the initial gels or weak flowing gels were obtained. Thus, the hydrogels showed thermoadaptive behavior, which might be an interesting property for future applications in sensing.

Self-assembly of the double hydrophilic block copolymer poly(N-vinylpyrrolidone)-b-poly(oligoethylene glycol methacrylate) and supramolecular crosslinking via α-cyclodextrin in water is presented.

The self-assembly of block copolymers in aqueous solution is an important field in modern polymer science that has been extended to double hydrophilic block copolymers (DHBC) in recent years. In here, a significant improvement of the self-assembly process of DHBC in aqueous solution by utilizing a linear-brush macromolecular architecture is presented. The improved self-assembly behavior of poly(N-vinylpyrrolidone)-b-poly(oligo(ethylene glycol) methyl ether methacrylate) (PVP-b-P(OEGMA)) and its concentration dependency is investigated via dynamic light scattering (DLS) (apparent hydrodynamic radii ≈ 100–120 nm). Moreover, the DHBC assemblies can be non-covalently crosslinked with tannic acid via hydrogen bonding, which leads to the formation of small aggregates as well (apparent hydrodynamic radius ≈ 15 nm). Non-covalent crosslinking improves the self-assembly and stabilizes the aggregates upon dilution, reducing the concentration dependency of aggregate self-assembly. Additionally, the non-covalent aggregates can be disassembled in basic media. The presence of aggregates was studied via cryogenic scanning electron microscopy (cryo-SEM) and DLS before and after non-covalent crosslinking. Furthermore, analytical ultracentrifugation of the formed aggregate structures was performed, clearly showing the existence of polymer assemblies, particularly after non-covalent crosslinking. In summary, we report on the completely hydrophilic self-assembled structures in solution formed from fully biocompatible building entities in water.