Precise Tailoring of Polyester Bottlebrush Amphiphiles toward Eco‐Friendly Photonic Pigments via Interfacial Self‐Assembly

Abstract

Biodegradable photonic microspheres with structural colors are promising substitutes to polluting microbeads and toxic dyes. Here, amphiphilic polyester‐block‐poly(ethylene glycol) bottlebrush block copolymers (BBCPs) with polylactic acid or poly(ϵ‐caprolactone) as the hydrophobic block are synthesized and used to fabricate eco‐friendly photonic pigments. Molecular parameters of BBCPs, including rigidity and symmetry, are precisely tailored by variation of side chain lengths, which enables effective manipulation of interfacial tension (γ). Organized spontaneous emulsion mechanism is enabled only when γ falls in a suitable range (10.6–14.3 mN m−1), producing ordered water‐in‐oil‐in‐water multiple emulsions and ordered porous structures. Consequently, highly saturated and tunable structural colors are observed due to coherent light scattering from the porous structures. Such photonic materials are nontoxic as confirmed by careful safety tests using aquatic model organisms.

Building block copolymer particles via self‐assembly within a droplet

“…77 Similarly, a series of porous BCP particles with controllable pore diameters have been fabricated by the self-assembly of bottlebrush BCPs based on the mechanism of organized spontaneous emulsification. [78][79][80][81][82]…”

Synthesis of Multiblock Bottlebrush Copolymers with Well-Defined Arbitrary Monomer Sequences: Key Factors Influencing Catalytic Stability

“…Living ring-opening metathesis polymerization (ROMP) represents a highly efficient and versatile approach to polymers with low-dispersity, tuneable topology, and diverse functions. , The third-generation Grubbs catalyst exhibited many attractive features including fast initiation, extremely rapid chain propagation, greatly suppressed chain transfer, and chain termination reactions. , Recently, Xia and Grubbs et al reported that narrowly dispersed diblock bottlebrush block copolymers (BBCPs) could be synthesized via grafting-through methods using living ROMP . Compared to their linear analogues, BBCPs show highly extended molecular backbones due to steric repulsions among the densely grafted polymeric side chains, resulting in greatly reduced intermolecular chain entanglements, , rapid self-assembly kinetics, − and large nanostructures with tuneable photonic band gaps. − Watkins group demonstrated the design and synthesis of amphiphilic diblock BBCPs using living ROMP, which were employed as the templates for directed self-assembly of functional nanoparticles into long-range ordered hybrid materials with advanced optical properties. ,, Other research groups (Rzayev, Wooley, Lodge et al) also reported the synthesis of triblock BBCPs for creation of nanostructured material through phase separation or well-controlled micellization in aqueous solutions. − However, the synthesis of multiblock bottlebrush copolymers (MBBCPs) remained scarce, and only limited sequences and a few blocks of no more than five were reported. − It is worth noting that tailing, shoulders, and broad dispersity (PDI >1.2) were usually observed in GPC curves of the obtained MBBCPs due to incomplete reinitiation of the resting Ru species. , For the synthetic procedure of sequential ROMP, a complete conversion of the first macromonomer (MM) is necessary before the addition of the second one to obtain MBBCPs with well-defined sequences. In this case, the death of catalytic species usually occur in a couple of hours through self-decomposition or because of bimolecular coupling under the monomer-absent condition. ,, Previous studies have mainly focused on acceleration of the polymerization rate by changing molecular structure of the MM, such as anchor groups, , stereochemistry, , and MW. , However, a long lif...…”

Poly(trimethylene carbonate)‐b‐poly(ethylene glycol) diblock copolymer micelles for hydrophobic drug delivery: The effect of hydrophilic/hydrophobic segment length on micellar properties and drug loading

“…In the past decades, synthetic biodegradable polymers such as polylactide, poly(ϵ-caprolactone), and polyhydroxybutyrate have been widely used to produce diblock copolymers. [19][20][21] Various micelle structures have been obtained from these copolymers for the application of PTX delivery such as spherical micelles, rod-like micelles, worm-like or filomicelles, polymesomes, and nanotubes. [22][23][24] For example, Burt et al 25 reported that paclitaxel was successfully encapsulated into diblock system composed of methoxypolyethylene glycol (MePEG), poly(D,L lactide), and poly(glycolide-co-caprolactone), respectively with the drug loading were up to 5%-10% w/w, and 15%-20% w/w, respectively.…”