Upgrading poly(styrene-co-divinylbenzene) beads: Incorporation of organomodified metal-free semiconductor graphitic carbon nitride through suspension photopolymerization to generate photoactive resins

The inclusion of the metal free semiconductor graphitic carbon nitride (g-CN) into polymer systems brings a variety of new options, for instance as a heterogeneous photoredox polymer initiator. In this context, we present here the decoration of the inner surface of poly(styrene-co-divinylbenzene) beads with organomodified g-CN via one pot suspension photopolymerization. The resulting beads are varied by changing reaction parameters, such as, crosslinking ratio, presence of porogens, and mechanical agitation. The photocatalytic activity of so-formed beads was tested by aqueous rhodamine B dye photodegradation experiments. Additionally, dye adsorption/desorption properties were examined in aqueous as well as in organic solvents. Photoinduced surface modification with vinylsulfonic acid and 4-vinyl pyridine is introduced. Overall, metal-free semiconductor g-CN donates photoactivity to polymer networks that can be employed for dye photodegradation and acid–base catalyst transformation through facile photoinduced surface modifications.     

D-A type hybrid polymers based on EDOT and various benzodiazoles for electrochromic materials

Two donor units (D)-acceptor units (A) type monomers were synthesized by Stille coupling reaction, and then three D-A type hybrid polymers based on 3,4-ethylenedioxythiophene and various benzodiazoles were synthesized by electrochemical polymerization. Spectroelectrochemical and kinetic studies of these polymers showed that all polymer films exhibited excellent electrochromic behavior, obvious optical contrast, and excellent stability. Among them, the response time of P3 film was the shortest (t_c = 1.6 s, t_b = 2.2 s), the coloring efficiency of P2 film was the highest (CE = 333 cm²·C⁻¹), and the stability of P1 was the best (the ΔT loss of P1 after 1000 s cycles is only 2.3%). Therefore, these data prove that these new polymers have great potential in applications as electrochromic materials.     

Tailoring the Mechanical Properties of 3D Microstructures Using Visible Light Post‐Manufacturing

The photochemistry of anthracene, a new class of photoresist for direct laser writing, is used to enable visible‐light‐gated control over the mechanical properties of 3D microstructures post‐manufacturing. The mechanical and viscoelastic properties (hardness, complex elastic modulus, and loss factor) of the microstructures are measured over the course of irradiation via dynamic mechanical analysis on the nanoscale. Irradiation of the microstructures leads to a strong hardening and stiffening effect due to the generation of additional crosslinks through the photodimerization of the anthracene functionalities. A relationship between the loss of fluorescence—a consequence of the photodimerization—and changes in the mechanical properties is established. The fluorescence thus serves as a proxy read‐out for the mechanical properties. These photoresponsive microstructures can potentially be used as “mechanical blank slates”: their mechanical properties can be readily adjusted using visible light to serve the demands of different applications and read out using their fluorescence.     

Preparation of Janus-type superparamagnetic iron oxide nanoparticles modified with functionalized PCL/PHEMA via photopolymerization for dual drug delivery

In this study, superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by the coprecipitation of FeCl₂˙4H₂O and FeCl₃˙6H₂O and applied as a core for preparation of Janus nanoparticles. Accordingly, freshly modified methacrylated iron oxide nanoparticles were reacted with two functionalized polymers. Acrylated poly(ε-caprolactone) (PCL) and acrylated poly(2-hydroxyethyl methacrylate) (PHEMA) were synthesized via ring-opening and free-radical polymerization, respectively, and subsequent modification with acryloyl chloride. Acrylated PCL as the hydrophobic part and acrylated PHEMA as the hydrophilic domain were grafted on the surface of methacrylated iron oxide nanoparticles with two morphologies. Pickering emulsion and solution photopolymerization reactions were used to prepare nanoparticles with “Janus” and “mixed” morphologies, respectively. The products were characterized in each step using Fourier-transform infrared spectroscopy (FT-IR), Proton nuclear magnetic resonance (¹H-NMR), thermogravimetric analysis (TGA), dynamic light scaterring (DLS), transmission electron microscope (TEM), vibrating-sample magnetometer (VSM), energy dispersive X-ray (EDX), and ultraviolet–visible spectroscopy (UV-Vis). Quercetin and 5-FU (as two anticancer drugs) were loaded in the mentioned nanoparticles, and the drug loading capacity and encapsulation efficiency (EE) of these nanoparticles were calculated. in vitro release behavior at two pH values (5.8 and 7.4) and at 37°C demonstrated that morphology can affect the release profile. Finally, rat C6 cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assay for drug-free and drug-loaded nanoparticles.     

光催化环己烷选择氧化合成环己酮/环己醇催化研究进展

环己烷选择性氧化合成环己醇/酮具有重要工业价值，工业上热氧化路线反应温度高、副反应多、转化率低、选择性不高，亟需条件更温和、更环保的替代路线。以太阳光为驱动的光催化环己烷氧化路线可在常温常压下实现环己烷的选择性氧化，受到极大关注。本文综述了近10年来光催化环己烷选择性氧化催化体系、反应机理和反应影响因素的研究情况，对光催化环己烷选择性氧化催化循环中环己烷分子活化、环己酮/醇形成、活性自由基再生的基元过程和催化剂失活机理进行总结和分析；对影响光催化环己烷选择性氧化的反应参数进行深入分析和讨论；指出·OH为主要的活性自由基，环己基过氧化氢是重要的中间产物，环己酮/醇主要通过环己基过氧化氢的光催化分解形成，光辐射条件（光强和波长）、溶剂、催化剂结构和表面性质都是光催化环己烷选择性氧化的重要影响因素。最后指出光催化环己烷选择性氧化规模化应用的关键是进一步提高光催化剂的寿命和稳定性以及设计结构合理、高效利用光能的光催化反应装置。     

Thiol‐ene photofunctionalization of 1,4‐polymyrcene

1,4‐Polymyrcene was synthesized by anionic polymerization of β‐myrcene and was subjected to photochemical functionalization with various thiols (i.e. methyl thioglycolate, methyl 3‐mercaptopropionate, butyl 3‐mercaptopropionate, ethyl 2‐mercaptopropionate and 2‐methyl‐2‐propanethiol) using benzophenone/UV light as the radical source. The yield of thiol addition to the trisubstituted double bonds of 1,4‐polymyrcene decreased in the order 1° thiol (ca 95%) > 2° thiol (ca 80%) > 3° thiol (<5%), due to the reversibility of the thiol‐ene reaction. Remarkably, thiol addition to the side‐chain double bonds was 8 ? 10 times (1° thiol) or 24 times (2° thiol) faster than to the main‐chain double bonds, which can be explained by the different accessibility of the double bonds and steric hindrance. Despite the use of a 10‐fold excess of thiol with respect to myrcene units, the thiol‐ene addition was accompanied by chain coupling reactions, which in the extreme case of 3° thiol (or in the absence of thiol) resulted in the formation of insoluble crosslinked material. As an example, a methyl‐thioglycolate‐functionalized 1,4‐polymyrcene was saponified/crosslinked to give submicron polyelectrolyte particles in dilute alkaline solution. © 2018 Society of Chemical Industry     

A Photoswitchable Trivalent Cluster Mannoside to Probe the Effects of Ligand Orientation in Bacterial Adhesion

We have recently demonstrated, by employing azobenzene glycosides, that bacterial adhesion to surfaces can be switched through reversible reorientation of the carbohydrate ligands. To investigate this phenomenon further, we have turned here to more complex—that is, multivalent—azobenzene glycoclusters. We report on the synthesis of a photosensitive trivalent cluster mannoside conjugated to an azobenzene hinge at the focal point. Molecular dynamics studies suggested that this cluster mannoside, despite the conformational flexibility of the azobenzene-glycocluster linkage, offers the potential for reversibly changing the glycocluster's orientation on a surface. Next, the photoswitchable glycocluster was attached to human cells, and adhesion assays with type 1 fimbriated Escherichia coli bacteria were performed. They showed marked differences in bacterial adhesion, dependent on the light-induced reorientation of the glycocluster moiety. These results further underline the importance of orientational effects in carbohydrate recognition and likewise the value of photoswitchable glycoconjugates for their study.     

Modelling heterogeneous photocatalytic oxidation using suspended TiO2 in a photoreactor working in continuous mode: Application to dynamic irradiation conditions simulating typical days in July and February

Compared to more conventional techniques, advanced oxidation processes (AOP) hold significant promise in terms of elimination of organic (especially persistent) compounds and microorganisms (disinfection) in wastewater. If the objective is to power these processes using solar energy, we need to be able to manage the intermittency in the solar resource. This is an essential step for design and to ensure efficient operation of the treatment processes. As solar radiation is inherently variable due to day/night cycles, seasonal cycles, and weather meteorological conditions, solar AOP performances are difficult to establish using conventional measures. To address this gap, we carry out experimental campaigns under controlled conditions and develop modelling tools capable of describing dynamic‐mode photocatalytic degradation. Here we develop a way to capture the responses of a photoreactor subjected to various stresses, including irradiation conditions, via an LED panel. Using a model that considers the influence of UV flux density and pollutant concentration made, it was possible to represent photoreactor responses under different irradiation conditions and feeds (concentration or flow at the input). The ultimate objective is to study the photocatalytic capacity of the photoreactor under irradiation conditions simulating a real day of sunshine.     

Conventionally facile fabrication of mechanically robust waterborne polyurethane with self-healing and photoluminescence

It is of much importance to synthesize waterborne polyurethane (WPUs) that simultaneously broaden the fields of applications and functions in a green strategy. In this paper, a novel class of WPUs were facilely prepared through the copolymerization between polytetrahydrofuran ether diol (PTMG), isophorone diisocyanate, and 2,2-bis(hydroxymethyl)propionic acid, which can achieve multiple functions of self-healing and photoluminescence after incorporating carbon quantum dots (CQs) into the WPUs. The prepared WPUs emulsion showed uniform size distribution from 61.97 nm to171.3 nm with different PTMG molecular weights. Especially, the maximum tensile strength and elongation at break of the WPUs can reach up to 69.78 MPa and 1879.99%, showing superior mechanical performance. After fractured surfaces held contact for 12 h at elevated temperature, the self-healing efficiency of the pristine WPUs can reach 21.39% for tensile strength and 24.79% for elongation at break. After adding CQs, the synthesized WPUs can also remain nearly the same tensile strength and elongation at break. Significantly, the self-healing WPUs with CQs can emit a bright orange fluorescence under ultraviolet light, showing outstanding photoluminescence. This kind of designed material takes advantages of simple preparation, no release of organic solvents during use, nontoxicity and harmlessness.