Symmetric Poly(ethylene oxide-b-styrene-b-isoprene) Triblock Copolymers: Synthesis, Characterization, and Self-Assembly in Bulk and Thin Film

Synthesis of platinum(II)-complex end-tethered polymers: spectroscopic properties and nanostructured particles

Although metal-containing polymers have been widely studied as a novel class of functional soft materials, the microphase separation between polymeric segments and metal-ligand complexes has been less addressed, which is critical to control their structures and functions. To do this, short-chain polystyrenes (PSs) have been end-functionalized with nanosized square-planar platinum(II) complexes. The platinum(II)-comprising polymers were found to show significant luminescence enhancement in chloroform/methanol solvent mixtures upon increasing the methanol composition. By modulating both the PS length and solvent quality, various self-assembled morphologies formed controllably in the mixed solvents and typical examples include nanofibers, nanoellipsoids, and nanospheres. More interestingly, the inside structures of these polymer particles are shown to be lamellar with sub-10 nm spacings, wherein the PS blocks are alternatively aligned with the platinum(II) units. Such a luminescence enhancement and hierarchical nanostructured particles originate from a subtle combination of directional Pt(II)⋯Pt(II) and/or π-π stacking interactions between the platinum(II) units and the solvophobic effect between the PS blocks. This work suggests that by microphase separating polymer chains with nanosized metal-ligand complexes, metal-containing polymers can self-assemble to form sub-10 nm scale nanostructures showcasing desired properties and functions.

Exploring the Self-Assembly Capabilities of ABA-Type SBS, SIS, and Their Analogous Hydrogenated Copolymers onto Different Nanostructures Using Atomic Force Microscopy

In this work, the self-assembled morphologies obtained for poly(styrene-b-butadiene-b-styrene) (SBS) and poly(styrene-b-isoprene-b-styrene) (SIS) ABA-type copolymers were investigated before and after hydrogenation of the polydiene block, which led to poly(styrene-b-ethylene)/poly(ethylene-b-styrene) (SEES) and poly(styrene-b-ethylene)/poly(propylene-b-styrene) (SEPS) copolymers, respectively. The evaluation of different morphologies was carried out using atomic force microscopy (AFM), analyzing the effect of various parameters such as the solvent and polymer concentrations employed for film casting (toluene, cyclohexane, or tetrahydrofurane with concentrations of 1 and 3 wt%), together with that of the annealing treatment (thermal annealing at room temperature, and 60, 80, and 100 °C). The effect of these parameters in combination with the chemical nature of the polydiene block led to different morphologies with different topographic aspects affecting the roughness (Ra) of the film.

Fabrication of Ordered Nanopattern by using ABC Triblock Copolymer with Salt in Toluene

Ordered nanopatterns of triblock copolymer polystyrene-block-poly(2-vinylpyridine)-block- poly (ethylene oxide)(PS-b-P2VP-b-PEO) have been achieved by the addition of lithium chloride (LiCl). The morphological and structural evolution of PS-b-P2VP-b-PEO/LiCl thin films were systematically investigated by varying different experimental parameters, including the treatment for polymer solution after the addition of LiCl, the time scale of ultrasonic treatment and the molar ratio of Li⁺ ions to the total number of oxygen atoms (O) in PEO block and the nitrogen atoms (N) in P2VP block. When toluene was used as the solvent for LiCl, ordered nanopattern with cylinders or nanostripes could be obtained after spin-coating. The mechanism of nanopattern transformation was related to the loading of LiCl in different microdomains.

Extraordinary boundary morphologies of large-scale ordered domains of spheres in thin films of a narrowly dispersed diblock copolymer via thermodynamic control

Long-range ordering of body centered cubic (BCC) spheres and various extraordinary morphologies at the boundaries of the adjacent orderly oriented domains are observed in thermally annealed thin films of a series of specific narrowly dispersed diblock copolymers, poly(dimethylsiloxane)-b-poly{2,5-bis[(4-butoxyphenyl)oxycarbonylstyrene} (PDMS-b-PBPCS, DB). The series of asymmetrical DB block copolymers (BCPs) with volume fractions of PDMS (f(PDMS)'s) from 10% to 23% self-assemble into thermodynamically stable body centered cubic (BCC) nanostructures in bulk at ambient temperature after thermal annealing. The thin films of these BCPs with a relatively large film thickness on a carbon-film coated substrate are annealed in a vacuum at 180 °C for 3 days and are characterized by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). For all thin films of these BCPs, micrometer-scale domains with a rectangular unit cell similar to the projection of the BCC lattice along the [110] direction to the substrate are observed. And the XPS results indicate that the surface layers of the thin films are composed of both PDMS and PBPCS blocks. For the thin films of the BCPs with f(PDMS) values of 10% and 13%, the neighboring [110]-oriented BCC domains match well with each other, and the boundaries are defect-free. For the thin film of the BCP with a f(PDMS) value of 23%, the PDMS spheres in the [110]-oriented BCC domains in the TEM micrograph are overlapped with each other, and interesting morphologies including defect-free interfaces, interfaces with line defects, and domains with defects and local ordering are observed at the boundaries of the neighboring [110]-oriented domains.

Inorganic nanoparticles engineered to attack bacteria

Antibiotics delivered to bacteria using engineered nanoparticles (NP), offer a powerful and efficient means to kill or control bacteria, especially those already resistant to antibiotics.