Rationally designed anionic diblock copolymer worm gels are useful model systems for calcite occlusion studies

Binary mixtures of anionic and non-ionic macromolecular chain transfer agents (macro-CTAs) are utilized in order to rationally design diblock copolymer nanoparticles with tunable morphologies and anionic character via pseudo-living radical polymerization. More specifically, poly(methacrylic acid) (PMAA) and poly(glycerol monomethacrylate) (PGMA) macro-CTAs are pre-mixed prior to reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization of 2-hydroxypropyl methacrylate (HPMA). This strategy facilitates the formation of PHPMA-based diblock copolymer spheres, worm-like micelles and vesicles via polymerization-induced self-assembly (PISA). The presence of the anionic PMAA stabilizer block has a dramatic impact on the resulting copolymer morphology, particularly if the degree of polymerization (DP) of the PMAA stabilizer chains is longer than that of the PGMA. Two phase diagrams have been constructed to investigate the effect of the relative proportion and molar mass of the two macro-CTAs. Such a systematic approach is essential for the reproducible synthesis of pure worm-like micelles, which occupy relatively narrow phase space. The rheological behavior of a series of soft, free-standing worm gels is investigated. Finally, such gels are examined as model matrices for the growth of biomimetic calcite crystals and the role of the anionic PMAA stabilizer chains in directing crystal growth is evaluated

Physical Confinement Promoting Formation of Cu2O−Au Heterostructures with Au Nanoparticles Entrapped within Crystalline Cu2O Nanorods

Building on the application of cuprite (Cu2O) in solar energy technologies and reports of increased optical absorption caused by metal-to-semiconductor energy transfer, a confinement-based strategy was developed to fabricate high aspect ratio, crystalline Cu2O nanorods containing entrapped gold nanoparticles (Au nps). Cu2O was crystallized within the confines of track-etch membrane pores, where this physical, assembly based method eliminates the necessity of specific chemical interactions to achieve a well-defined metal−semiconductor interface. With high-resolution scanning/transmission electron microscopy (S/TEM) and tomography, we demonstrate the encasement of the majority of Au nps by crystalline Cu2O and show crystalline Cu2O−Au interfaces that are free of extended amorphous regions. Such nanocrystal heterostructures are good candidates for studying the transport physics of metal/semiconductor hybrids for optoelectronic applications

Cooperative Effects of Confinement and Surface Functionalization Enable the Formation of Au/Cu₂O Metal–Semiconductor Heterostructures

A promising approach to obtaining multifunctional materials with tunable properties is the incorporation of second phase constituents (e.g., particles, fibers) within inorganic crystals. To date, however, the specific chemical and physical controls over incorporation are only known for a few select systems. In this study, a simple wedge is used as a confining structure to systematically control the chemical and physical aspects of the crystallization microenvironment to promote the interaction between copper­(I) oxide (Cu₂O) crystals and alkanethiol-functionalized gold nanoparticles (Au np), producing a metal–semiconductor composite. Physically, the confining wedge geometry provides (vapor) diffusion-limited growth conditions. Chemically functionalizing both the Au np surfaces and the glass slides that form the wedge promotes the interaction of Au np with the growing Cu₂O crystals. The physical confinement of the wedge structure, as well as optimization of its surface chemistry, is required to achieve this interaction. These findings demonstrate that Au/Cu₂O can be used as a model system to inform the synthesis of other metal–semiconductor heterostructures

Cooperative Effects of Confinement and Surface Functionalization Enable the Formation of Au/Cu2O Metal-Semiconductor Heterostructures

A promising approach to obtaining multifunctional materials with tunable properties is the incorporation of second phase constituents (e.g., particles, fibers) within inorganic crystals. To date, however, the specific chemical and physical controls over incorporation are only known for a few select systems. In this study, a simple wedge is used as a confining structure to systematically control the chemical and physical aspects of the crystallization microenvironment to promote the interaction between copper(I) oxide (Cu2O) crystals and alkanethiol-functionalized gold nanoparticles (Au np), producing a metal–semiconductor composite. Physically, the confining wedge geometry provides (vapor) diffusion-limited growth conditions. Chemically functionalizing both the Au np surfaces and the glass slides that form the wedge promotes the interaction of Au np with the growing Cu2O crystals. The physical confinement of the wedge structure, as well as optimization of its surface chemistry, is required to achieve this interaction. These findings demonstrate that Au/Cu2O can be used as a model system to inform the synthesis of other metal–semiconductor heterostructures