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Unlike inorganic nanoparticles, organic nanoparticles (oNPs) offer the advantage of “interior tailorability,” thereby enabling the controlled variation of physicochemical characteristics and functionalities, for example, by incorporation of diverse functional small molecules. In this study, a unique inimer-based microemulsion approach is presented to realize oNPs with enhanced control of chemical and mechanical properties by deliberate variation of the degree of hyperbranching or cross-linking. The use of anionic cosurfactants led to oNPs with superior uniformity. Benefitting from the high initiator concentration from inimer and preserved chain-end functionality during atom transfer radical polymerization (ATRP), the capability of oNPs as a multifunctional macroinitiator for the subsequent surface-initiated ATRP was demonstrated. This facilitated the synthesis of densely tethered poly(methyl methacrylate) brush oNPs. Detailed analysis revealed that exceptionally high grafting densities (~1 nm⁻²) were attributable to multilayer surface grafting from oNPs due to the hyperbranched macromolecular architecture. The ability to control functional attributes along with elastic properties renders this “bottom-up” synthetic strategy of macroinitiator-type oNPs a unique platform for realizing functional materials with a broad spectrum of applications. 

Untethered electrical stimulation or pacing of the heart is of critical importance in addressing the pressing needs of cardiovascular diseases in both clinical therapies and fundamental studies. Among various stimulation methods, light illumination–induced electrical stimulation via photoelectric effect without any genetic modifications to beating cells/tissues or whole heart has profound benefits. However, a critical bottleneck lies in the lack of a suitable material with tissue-like mechanical softness and deformability and sufficient optoelectronic performances toward effective stimulation. Here, we introduce an ultrathin (<500 nm), stretchy, and self-adhesive rubbery bio-optoelectronic stimulator (RBOES) in a bilayer construct of a rubbery semiconducting nanofilm and a transparent, stretchable gold nanomesh conductor. The RBOES could maintain its optoelectronic performance when it was stretched by 20%. The RBOES was validated to effectively accelerate the beating of the human induced pluripotent stem cell–derived cardiomyocytes. Furthermore, acceleration of ex vivo perfused rat hearts by optoelectronic stimulation with the self-adhered RBOES was achieved with repetitive pulsed light illumination. 

Structurally well-defined polymer-grafted nanoparticle hybrids are highly sought after for a variety of applications, such as antifouling, mechanical reinforcement, separations, and sensing. Herein, we report the synthesis of poly(methyl methacrylate) grafted- and poly(styrene) grafted-BaTiO3 nanoparticles using activator regeneration via electron transfer (ARGET ATRP) with a sacrificial initiator, atom transfer radical polymerization (normal ATRP), and ATRP with sacrificial initiator, to understand the role of the polymerization procedure in influencing the structure of nanoparticle hybrids. Irrespective of the polymerization procedure adopted for the synthesis of nanoparticle hybrids, we noticed PS grafted on the nanoparticles showed moderation in molecular weight and graft density (ranging from 30,400 to 83,900 g/mol and 0.122 to 0.067 chain/nm2) compared to PMMA-grafted nanoparticles (ranging from 44,620 to 230,000 g/mol and 0.071 to 0.015 chain/nm2). Reducing the polymerization time during ATRP has a significant impact on the molecular weight of polymer brushes grafted on the nanoparticles. PMMA-grafted nanoparticles synthesized using ATRP had lower graft density and considerably higher molecular weight compared to PS-grafted nanoparticles. However, the addition of a sacrificial initiator during ATRP resulted in moderation of the molecular weight and graft density of PMMA-grafted nanoparticles. The use of a sacrificial initiator along with ARGET offered the best control in achieving lower molecular weight and narrow dispersity for both PS (37,870 g/mol and PDI of 1.259) and PMMA (44,620 g/mol and PDI of 1.263) nanoparticle hybrid systems. 

The synthesis of polymer-grafted nanoparticles (PGNPs) or hairy nanoparticles (HNPs) by tethering of polymer chains to the surface of nanoparticles is an important technique to obtain nanostructured hybrid materials that have been widely used in the formulation of advanced polymer nanocomposites. Ceramic-based polymer nanocomposites integrate key attributes of polymer and ceramic nanomaterial to improve the dielectric properties such as breakdown strength, energy density and dielectric loss. This review describes the ”grafting from” and ”grafting to” approaches commonly adopted to graft polymer chains on NPs pertaining to nano-dielectrics. The article also covers various surface initiated controlled radical polymerization techniques, along with templated approaches for grafting of polymer chains onto SiO2, TiO2, BaTiO3, and Al2O3 nanomaterials. As a look towards applications, an outlook on high-performance polymer nanocomposite capacitors for the design of high energy density pulsed power thin-film capacitors is also presented. 

The block copolymer (BCP) phase separation is an intriguing phenomenon, the dynamics of which can be expected to differ significantly from that of the polymer blends due to the chain connectivity constraints. The BCP phase separation dynamics has been studied theoretically, but there has been little experimental evidence to confirm the BCP domain growth scaling laws put forward by theoretical studies. Here, we demonstrate the dynamics of late-stage lamellar BCP domain coarsening and show that the scaling exponent for domain growth is ≈1/6 (0.17) irrespective of the annealing temperature, which is close to the scaling exponent of 0.2 shown by theoretical studies. Furthermore, we show that the pre-factors in the domain coarsening equation show Arrhenius dependence on temperature indicating that the BCP domain growth dynamics is Arrhenius.