Ternary block copolymer (BCP)-homopolymer (HP) blends offer a simple method for tuning nanostructure sizes to meet application-specific demands. Comprehensive dissipative particle dynamic (DPD) simulations were performed to study the impact of polymer interactions, molecular weight, and HP volume fraction (φ HP ) on symmetric ternary blend morphological stability and domain spacing. DPD reproduces key features of the experimental phase diagram, including lamellar domain swelling with increasing φ HP , the formation of an asymmetric bicontinuous microemulsion at a critical HP concentration φ * HP , and macrophase separation with further HP addition. Simulation results matched experimental values for φ * HP and lamellar swelling as a function of HP to BCP chain length ratio, α = N HP /N BCP . Structural analysis of blends with fixed φ HP but varying α confirmed that ternary blends follow the wet/dry brush model of domain swelling with the miscibility of HPs and BCPs depending on α. Longer HPs concentrate in the center of domains, boosting their swelling efficiencies compared to shorter chains. These results advance our understanding of BCP-HP blend phase behavior and demonstrate the value of DPD for studying polymeric blends.

Abstract:Commercial and Synthesized titanium di oxide (TiO 2 ) prepared by conventional sol-gel method, are modified to degrade industrial dyes. Modification is done on bare TiO 2 and TiO 2 doped with various doping agents (activated charcoal/silicon dioxide/zinc oxide), followed by thermal treatments. The role of thermal treatments and doping effects on the efficiency of TiO 2 photocatalysts are highlighted and evaluated by decoloration of Methylene Blue in aqueous solution under UV and Visible light irradiation for both systems. The results revealed that increase in calcination temperature up to optimum level enhances the photocatalytic activities of the samples and doping narrows the band gap and makes the samples visible light responsive. This study also showed that activated charcoal (AC) doped TiO 2 photocatalyst is a promising one under Visible light and is thus used to degrade other dyes such as Crystal Violet and Rhodamine B. The obtained experimental data are used to study four different kinetic models: Zero order, Pseudo first order, Parabolic diffusion and Modified Freundlich model. The best fit of the experimental data are obtained by Pseudo first order and Modified Freundlich models.

The thin film phase behavior of ternary blends consisting of symmetric poly(styrene) (PS)‐b‐poly(dimethylsiloxane)(PDMS), PS, and PDMS was investigated using X‐ray reflectivity (XRR) and atomic force microscopy (AFM). This system is strongly segregated, and the homopolymers are approximately the same length as the corresponding blocks of the copolymer. The XRR and AFM data are used to quantify changes in domain spacing (L) and morphology evolution with increasing homopolymer content (Φ H). In 100 nm thick films, from Φ H = 0 to 0.20, the system maintains a perfect parallel lamellar structure and domains swell as predicted based on theory; however, from Φ H = 0.30 to 0.50, a morphology transition to a “dot pattern” morphology (tentatively identified as perforated lamellae) and mixed morphologies were observed before macrophase separation. In thicker films, dot patterns were observed for a broad range of Φ H before macrophase separation. The absence of the bicontinuous microemulsion phase reported for bulk blends and thin films of perpendicular lamellae and the presence of dot patterns/perforated lamellae are attributed to preferential migration of the PDMS homopolymer to the wetting layers located at the substrate and free air interfaces, which leads to an asymmetric composition within the film and morphology transition. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1443–1451