Ultrasonic degradation of polymers is well known already. This article presents an interesting and simple method about ultrasonic degradation of polymer chains which could be amplified by a magnetic field efficiently. A polystyrene-poly acrylic acid (PS-PAA) brush which averaged 238 nm in thickness was employed in the method. After ultrasonic treatment with the frequency at 35 kHz at 303 K for 6 hours, the thickness of PAA chains decreased by 83 nm while it decreased by 180 nm dramatically with the same ultrasonic irradiation coupled with a magnetic field (20 mT). It implied that there was a synergetic effect of ultrasound and magnetic field on the degradation of PAA chains. Increasing the magnetic field intensity or ultrasonic frequency could decrease the residual thickness of PAA chains as well as which could be done by decreasing the temperature. In the experimental range, it's surprising that the thickness of PAA chains decreased from 238 nm to 14 nm after 5 h treatment (20 mT, 53 kHz, 288 K) and the average molecular weight of the PAA chains on the surface of the core decreased from 2.5 × 105 to 1.5 × 104 g mol−1. Different characterizations, such as UV-vis, FTIR, DLS, rheology, KI dosimetry and calorimetry study etc. were employed in this work. Based on the experimental results, a reasonable mechanism was proposed as the magnetic field decreased the viscosity of the brush solution which could enhance the effect of the acoustic cavitation. In all, this work provides a simple and green method on the degradation of polymer brushes and may have applications in material chemistry and environmental engineering in future.

In this work, we demonstrated a facile and environmentally friendly method of preparing water-soluble cadmium sulfide (CdS) quantum dots (QDs) immobilized in spherical polyelectrolyte brushes (SPBs). The synthesis included three stages as follows: preparation of SPBs, introduction of Cd2+ by the ion-exchange process and in situ fabrication of CdS in SPBs. The X-ray diffraction (XRD) pattern and the transmission electron microscopy (TEM) images proved that the CdS nanocrystallines (NCs) were cubic in structure and well distributed in SPBs. The size and photoluminescence (PL) emission of hybrid nanoparticles (SPB@CdS) could be tailored by adjusting some parameters, such as pH of SPBs, the ratio of Cd/S, the temperature of reaction and dimensions of SPB@CdS. For instance, upon increasing the pH value of SPBs and the ratio of Cd/S, the trap emission of CdS NCs could be transformed into band-edge emission. And the PL emission shifted from 490 to 580 nm as the reaction temperature increased from 10 to 90 °C. More interesting was that the PL emission of SPB@CdS could be quenched and recovered reversibly by pH adjustment due to the pH sensitive chains of poly(acrylic acid) grafting from the polystyrene core. The SPB@CdS displayed excellent photochemical stability in visible light above pH 10 which provided a possibility for storing QDs in visible light. In addition, this simple method can be extended to other sulfide fabrication in SPBs, such as ZnS, which has also been successfully embedded in SPBs.

Spherical particles of α-, β- and γ-cyclodextrin (CD) polymers to efficiently remove phenol from waste water were prepared by reverse suspension polymerization with epichlorohydrin as crosslinker in liquid paraffin. By controlling the amounts of crosslinker and water, well-defined spherical polymer particles with controllable size were obtained. Due to the selective inclusion associations between CD groups and phenol, these CD spherical polymer particles were demonstrated to be ideal candidates for removal of phenol. Among them β-CD polymer particles showed the best performance. The kinetics and isothermal equilibrium models were used to fit the experimental data of phenol removal from aqueous solution using these CD polymer particles. It was found that the kinetics followed the Ho and Mckay equation, suggesting that the adsorption process of phenol was controlled by diffusion and the host-guest interaction between CD and phenol. Equilibrium isothermal data can be well fitted by the Freundlich equation. The negative free energy change indicated the spontaneous nature of adsorption of phenol by α-, β- and γ-CD spherical polymer particles, while the lowest free energy for β-CD polymer reflected its best adsorption ability, compared to α- and γ-CD polymer particles.

In this work, we demonstrated a facile and environmentally friendly method of preparing water-soluble cadmium sulfide (CdS) quantum dots (QDs) immobilized in spherical polyelectrolyte brushes (SPBs). The synthesis included three stages as follows: preparation of SPBs, introduction of Cd2+ by the ion-exchange process and in situ fabrication of CdS in SPBs. The X-ray diffraction (XRD) pattern and the transmission electron microscopy (TEM) images proved that the CdS nanocrystallines (NCs) were cubic in structure and well distributed in SPBs. The size and photoluminescence (PL) emission of hybrid nanoparticles (SPB@CdS) could be tailored by adjusting some parameters, such as pH of SPBs, the ratio of Cd/S, the temperature of reaction and dimensions of SPB@CdS. For instance, upon increasing the pH value of SPBs and the ratio of Cd/S, the trap emission of CdS NCs could be transformed into band-edge emission. And the PL emission shifted from 490 to 580 nm as the reaction temperature increased from 10 to 90 °C. More interesting was that the PL emission of SPB@CdS could be quenched and recovered reversibly by pH adjustment due to the pH sensitive chains of poly(acrylic acid) grafting from the polystyrene core. The SPB@CdS displayed excellent photochemical stability in visible light above pH 10 which provided a possibility for storing QDs in visible light. In addition, this simple method can be extended to other sulfide fabrication in SPBs, such as ZnS, which has also been successfully embedded in SPBs.