Confined Microenvironments from Thermoresponsive Dendronized Polymers

Abstract

Confined microenvironments in biomacromolecules arising from molecular crowding account for their well‐defined biofunctions and bioactivities. To mimick this, synthetic polymers to form confined structures or microenvironments are of key scientific value, which have received significant attention recently. To create synthetic confined microenvironments, molecular crowding effects and topological cooperative effects have been applied successfully, and the key is balance between self‐association of structural units and self‐repulsion from crowding‐induced steric hindrance. In this article, formation of confined microenvironments from stimuli‐responsive dendronized polymers carrying densely dendritic oligoethylene glycols (OEGs) moieties in their pendants is presented. These wormlike thick macromolecules exhibit characteristic thermoresponsive properties, which can provide constrained microenvironments to encapsulate effectively guest molecules including dyes, proteins, or nucleic acids to prevent their protonation or biodegradation. This efficient shielding effect can also mediate chemical reactions in aqueous phase, and even enhance chirality transferring efficiency. All of these can be switched off simply through the thermally‐induced dehydration and collapse of OEG dendrons due to the amphiphilicity of OEG chains. Furthermore, the switchable encapsulation and release of guests can be greatly enhanced when these dendronized polymers are used as major constituents for fabricating bulk hydrogels or nanogels, which provide a higher‐level confinement.

Thermoresponsive Supramolecular Assemblies from Dendronized Amphiphiles To Form Fluorescent Spheres with Tunable Chirality

“…Among various molecular structures of the supramolecular monomers, dendritic amphiphiles have been proven to readily form supramolecular assemblies with confined morphologies due to their topological structures and characteristic multivalency, leading to biofunctions and biomaterials. − The dense packing of the dendritic moieties may provide pronounced crowding effects to mediate the assembled morphologies and at the same time impart featured encapsulation and shielding of guest moieties . Therefore, supramolecular chiral assembly from dendritic amphiphiles has received considerable attention to achieve defined morphologies with enhanced chirality. − …”

“…Supramolecular assemblies showing stimuli-responsive properties are appealing, which not only offer a convenient way to tune the assembled morphologies in situ through mediating the aggregation-driving forces with external stimuli but also afford the assemblies with intriguing stimuli-responsiveness as smart supramolecular materials. , Various stimuli have been applied for this purpose, including temperature, − pH, oxidation, and even phosphorylation . Among them, thermoresponsive supramolecular assemblies are extremely interesting due to their easy tunability in aqueous solutions, which affords advantages of supramolecular chemistry for potential bioapplications …”

Modulating the Thermoresponse of Polymer-Protein Conjugates with Hydrogels for Controlled Release

“…There is a similar effect (but to a lesser extent) seen from free P(D 30 T 70 ) and P(T 100 ) polymers in the pCB hydrogel. We hypothesize that this effect may be due to molecular crowding promoted by hydrogels, which can therefore induce phase transitions of stimuli responsive polymers at a lower temperature [ 24 , 25 , 26 , 27 ]. Furthermore, PEGMA phase transitions through multistep aggregation; therefore, the simultaneous effects of macromolecular crowding combined with reduced diffusivity, which influences aggregates size, can result in the broadening of phase transition temperatures curves [ 28 , 29 , 30 ].…”

How to Build a Microplastics‐Free Environment: Strategies for Microplastics Degradation and Plastics Recycling

“…With proper control over processing conditions, the degradation of physical properties in first several cycles can be suppressed. [ 120 ] Nevertheless, the gradual thermo‐oxidative or hydrolytic scission of polymers can give rise to the decrease of quality and loss of performance, which limits the sustainability of the mechanical recycling. Several types of polymers (e.g., polyurethane) cannot be recycled mechanically.…”