Reversible addition-fragmentation chain transfer (RAFT) radical dispersion polymerization (RAFTDP) has been employed to polymerize 2-phenylethyl methacrylate (PEMA) using poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) macromolecular chain transfer agents (macro-CTAs) of varying average degree of polymerization (X̄n).

Poly(stearyl methacrylate) (PSMA) homopolymers, prepared by RAFT radical polymerization, have been employed in the RAFT dispersion polymerization (RAFTDP) of 3-phenylpropyl methacrylate (PPMA) in n-tetradecane. RAFTDPs yielded block copolymers with narrow molecular weight distributions and tunable compositions and allowed for ready access to different polymorphic nanoparticle phases. Polymerization of PPMA at 20 wt %, for a fixed PSMA average degree of polymerization (X̅ n ) of 19, allowed for the in situ preparation of soft matter nano-objects with spherical, worm, and vesicular morphologies. For a fixed block copolymer composition increasing total solids (from 10 to 40 wt %) favored the formation of nanoparticles with higher ordered morphologies. For block copolymer samples that formed soft physical gels at ambient temperature, a macroscopic thermoreversible degelation−gelation phenomenon was observed. The fundamental reason for this was a worm-to-sphere morphology transition that was facilitated, in part, by the low glass transition temperature of the core-forming PPPMA block and an associated increase in the solvation of the core with increasing temperature. Finally, we note that degelation can also be effected by simple dilution with this macroscopic change now due to simple worm disentanglement and not a fundamental morphology transition. ■ INTRODUCTIONThe ability of block copolymers to undergo self-directed assembly in a selective solvent is well documented. 1 Assembly occurs to give soft matter nanoparticles with, most commonly, a spherical morphology although higher ordered; more complex structures are also accessible. 2−14 Traditionally, such selfassembled species are prepared by first synthesizing a welldefined block copolymer (most commonly, but not limited to, an AB diblock species) which, after characterization, is subjected to a processing step to give the nanoparticles. This may involve direct dissolution in a selective solvent or may require additional steps such as gradual stepwise dialysis against a selective solvent from a molecularly dissolved state. While these are well established and perfectly valid approaches to accessing polymeric nanoparticles, this is typically accomplished in dilute solution (≤1 wt % is common), and nano-objects other than spheres can be difficult to obtain.Reversible addition−fragmentation chain transfer dispersion polymerization (RAFTDP) 15−18 has recently been the topic of significant academic interest since it allows for the direct in situ preparation of self-assembled polymeric species of various morphologies (spheres, worms, and vesicles as the most common species) at high concentration (formulations at ≥ 50 wt % are readily achievable) in a one-pot process. The ease of execution and potential versatility of this technique have enabled the syntheses of a wide range of interesting nanoparticles in polar 19−32 (typically aqueous or alcoholic solvents), nonpolar, 33−36 and other, less common, media such as supercritical CO 2 . 37,38 Indeed, RAFTDP is now sufficient...

Viral infections are a serious health challenge, and the COVID-19 pandemic has increased the demand for antiviral measures and treatments for clean surfaces, especially in public places. Here, we review a range of natural and synthetic surface materials and coatings with antiviral properties, including metals, polymers and biopolymers, graphene and antimicrobial peptides, and their underpinning antiviral mechanisms. We also discuss the physico-chemical properties of surfaces which influence virus attachment and persistence on surfaces. Finally, an overview is given of the current practices and applications of antiviral and virucidal materials and coatings in consumer products, personal protective equipment, healthcare and public settings.

"smart" materials rely on very distinct material responses on a macroscopic and/or microscopic level. This can be achieved by crafting stimulus-responsive polymers into nanostructured materials, including smart nanoparticles, which are receiving increasing attention specifically in the biomedical field. [2,3] Amphiphilic block copolymers are well-known to undergo self-directed assembly in selective solvents providing access to a range of soft matter nanoparticles [4][5][6][7] with applications in coatings, [8] electronics, [9] drug delivery, [10] and cancer therapy, [11,12] among others. Traditionally, the preparation of such nanoparticles has been accomplished by initial synthesis and molecular dissolution of well-defined parent copolymers which are subsequently "processed", often via time-consuming step-wise dialysis, to give the targeted nano-object. Another drawback of this well-established approach is the generally low concentration of the final copolymer nanoparticles (≤1.0 wt% is common) which limits industrial application and study of such nanoparticles in areas where high Polymerization-induced self-assembly (PISA) is an extremely versatile method for the in situ preparation of soft-matter nanoparticles of defined size and morphologies at high concentrations, suitable for large-scale production. Recently, certain PISA-prepared nanoparticles have been shown to exhibit reversible polymorphism ("shape-shifting"), typically between micellar, worm-like, and vesicular phases (order-order transitions), in response to external stimuli including temperature, pH, electrolytes, and chemical modification. This review summarises the literature to date and describes molecular requirements for the design of stimulus-responsive nano-objects. Reversible pH-responsive behavior is rationalised in terms of increased solvation of reversibly ionized groups. Temperature-triggered order-order transitions, conversely, do not rely on inherently thermo-responsive polymers, but are explained based on interfacial LCST or UCST behavior that affects the volume fractions of the core and stabilizer blocks. Irreversible morphology transitions, on the other hand, can result from chemical post-modification of reactive PISA-made particles. Emerging applications and future research directions of this "smart" nanoparticle behavior are reviewed.