Constructing Cylindrical Nanostructures Via Directional Morphology Evolution Induced by Seeded Polymerization.

Herein, spindle-shaped block copolymer (BCP) nanoparticles are used in seeded polymerization of methyl methacrylate as a novel approach to generating cylindrical nanostructures. The chain-extension of BCP seeds by an amorphous coil-type polymer within the seed core composed of semifluorinated liquid-crystalline blocks triggers the deforming, stretching, and directional growth of the seeds along the long axis, eventually leads to nanorods.

Directional effect on the fusion of ellipsoidal morphologies into nanorods and nanotubes.

Particle fusion is well-recognized as an important spontaneous process to produce higher-order nanostructures during morphology transition in polymerization-induced self-assembly (PISA). However, to our knowledge, the directional contact, adhesion, and fusion of adjacent nanoparticles have been rarely elucidated in PISA. Herein, a directional fusion of ellipsoidal morphologies was demonstrated during PISA of semi-fluorinated liquid-crystalline (SFLC) block copolymers. The ellipsoidal nanostructures, including micelles and vesicles, preferred to undergo a directional fusion in a head-to-head model, leading to the formation of nanorods and nanotubes, respectively. We believe the directional fusion will offer insightful guidance in PISA to the preparation of complicated functional nanostructures.

Directed arrangement of siRNA via polymerization-induced electrostatic self-assembly.

Herein, polymerization-induced electrostatic self-assembly (PIESA) is conducted to mediate the self-assembly behavior of short interfering RNA (siRNA) for the first time. In PIESA, siRNA not only formed a simple electrostatic polyplex with positively charged polycations, but also facilitated directed self-assembly due to the molecular rigidity of siRNA, leading to appealing nanotubes.

Photocontrolled RAFT Polymerization Mediated by a Supramolecular Catalyst.

A photocontrolled reversible addition-fragmentation chain transfer (RAFT) polymerization mediated by a supramolecular photoredox catalyst is reported. Cucurbit[7]uril (CB[7]) was used to form a host-guest complex with Zn(II) meso-tetra(4-naphthalylmethylpyridyl) porphyrin (ZnTPOR) to prevent aggregation of ZnTPOR, which in combination with a chain transfer agent (CTA) initiated efficient and controlled RAFT polymerization in water under visible light. RAFT polymerization was significantly affected by the subtle interplay of host-guest, electrostatic, and steric interactions among CB[7], ZnTPOR, and CTA. Polymerization rate was remarkably improved using CB[7]@ZnTPOR in comparison with that using ZnTPOR. The use of supramolecular interactions to modulate photocontrolled RAFT polymerization provides new opportunities to manipulate controlled radical polymerizations.

Adsorption isotherm, kinetic and mechanism of expanded graphite for sulfadiazine antibiotics removal from aqueous solutions.

The adsorption of sulfadiazine from water by expanded graphite (EG), a low cost and environmental-friendly adsorbent, was investigated. Several adsorption parameters (including the initial sulfadiazine concentration, contact time, pH of solution, ionic strength and temperature) were studied. Results of equilibrium experiments indicated that adsorption of sulfadiazine onto EG were better described by the Langmuir and Tempkin models than by the Freundlich model. The maximum adsorption capacity is calculated to be 16.586 mg/g at 298 K. The kinetic data were analyzed by pseudo-first-order, pseudo-second-order and intraparticle models. The results indicated that the adsorption process followed pseudo-second-order kinetics and may be controlled by two steps. Moreover, the pH significantly influenced the adsorption process, with the relatively high adsorption capacity at pH 2-10. The electrostatic and hydrophobic interactions are manifested to be two main mechanisms for sulfadiazine adsorption of EG. Meanwhile, the ionic concentration of Cl- slightly impacted the removal of sulfadiazine. Results of thermodynamics analysis showed spontaneous and exothermic nature of sulfadiazine adsorption on EG. In addition, regeneration experiments imply that the saturated EG could be reused for sulfadiazine removal by immersing sodium hydroxide.