Precipitation Polymerization in Acetic Acid: Synthesis of Monodisperse Cross-Linked Poly(divinylbenzene) Microspheres

Super-adsorbent microspheres based on a triallyl isocyanurate-maleic anhydride copolymer for the removal of organic pollutants from water

Owing to the frequent occurrence of diclofenac sodium (DS) in fresh aquatic environments and its potential toxicity towards living organisms, the effective removal of DS has attracted worldwide attention. Herein, a green and efficient strategy to fabricate crosslinked microspheres with interconnected mesoporous structures and abundant adsorption active sites was developed. With this strategy, triallyl isocyanurate (TAIC)-maleic anhydride (MAH) copolymer microspheres (TMs) with a diameter of 1.19-1.35 μm were first prepared by self-stabilized precipitation (2SP) polymerization, and the TMs possess a large amount reactive anhydride groups (62.5-71.8 mol%), a specific surface area of 51.6-182.4 m² g^-1 and a mesoporous structure (average pore size: 3.4-3.8 nm). Then the TMs were further functionalized with polyethylenimine (PEI) to give rise to cationic microspheres (Cat-TMs), which showed excellent adsorption performance to DS with a rapid adsorption rate (reached equilibrium within 30 min), a very high equilibrium adsorption capacity (1421 mg g^-1) and excellent recyclability. The pseudo-second-order model and Langmuir model were a good fit for the adsorption kinetic and isotherm process, respectively. Furthermore, due to the high cation density (4.291 mmol g^-1) and excellent pH buffer capacity of Cat-TMs, the adsorption capacity can be maintained at a high level within the pH range of 6-10. The regenerated Cat-TMs showed only a slight loss (<5%) in the adsorption capacity even after 5 adsorption-desorption cycles. In short, Cat-TMs can be considered as a highly promising adsorbent for the rapid and ultra-efficient removal of anionic organic contaminants and have significant potential to be applied in wastewater treatment.

Conjugated and Non-conjugated Polymers Containing Two-Electron Redox Dihydrophenazines for Lithium-Organic Batteries

Organic p-type cathode materials have recently attracted increasing attention due to their higher redox potentials and rate capabilities in comparison to n-type cathodes. However, most of the p-type cathodes based on one-electron redox still suffer from limited stability and low specific capacity (<150 mAh g^-1 ). Herein, two polymers, conjugated poly(diethyldihydrophenazine vinylene) (CPP) and non-conjugated poly(diethyldihydrophenazine ethylidene) (NCPP) containing two-electron redox dihydrophenazine, have been developed as p-type cathode materials. It is experimentally and theoretically found that the conjugated linkage among the redox centers in polymer CPP is more favorable for the effective charge delocalization on the conjugated polymer backbone and the sufficient oxidation in the higher potential region (3.3-4.2 V vs. Li/Li⁺ ). Consequently, the CPP cathode displays a higher reversible specific capacity of 184 mAh g^-1 with excellent cycling stability.

Self-Stable Precipitation Polymerization Molecular Entanglement Effect and Molecular Weight Simulations and Experiments

In this paper, we developed a reactive molecular dynamics (RMD) scheme to simulate the Self-Stable Precipitation (SP) polymerization of 1-pentene and cyclopentene (C5) with maleic anhydride (MAn) in an all-atom resolution. We studied the chain propagation mechanism by tracking the changes in molecular conformation and analyzing end-to-end distance and radius of gyration. The results show that the main reason of chain termination in the reaction process was due to intramolecular cyclic entanglement, which made the active center wrapped in the center of the globular chain. After conducting the experiment in the same condition with the simulation, we found that the distribution trend and peak value of the molecular-weight-distribution curve in the simulation were consistent with experimental results. The simulated number average molecular weight (Mn) and weight average molecular weight (Mw) were in good agreement with the experiment. Moreover, the simulated molecular polydispersity index (PDI) for cyclopentene reaction with maleic anhydride was accurate, differing by 0.04 from the experimental value. These show that this model is suitable for C5–maleic anhydride self-stable precipitation polymerization and is expected to be used as a molecular weight prediction tool for other maleic anhydride self-stable precipitation polymerization system.

Effect of Formulation on the Binding Efficiency and Selectivity of Precipitation Molecularly Imprinted Polymers

This study investigated the effect of feed formulation: the template:functional monomer (T:fM) and functional monomer:crosslinker (fM:X) ratios as well as the initiator concentration, on the binding performance and selectivity of caffeine (CAF) and theophylline (THP) imprinted polymers obtained by precipitation polymerisation in acetonitrile at 60 °C using methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and crosslinker, respectively. Template incorporation, monitored by quantitative ¹H-NMR spectroscopy, ranged from 8 to 77% and was found to be more favourable at both high and low T:fM ratios, low fM:X ratio and high initiator concentration. The resulting T:fM ratio in most MIPs were found to be lower than their feed ratios. Incorporation of THP into the polymers was observed to be consistently higher than CAF and, for most MIPs, the observed binding capacities represent less than 10% of the incorporated template. Improved imprinting factors were obtained from molecularly imprinted polymers (MIPs) with high crosslinker content, i.e., fM:X ratio of 1:10, and high initiator concentration, i.e., initiator:total monomer (I:tM) ratio of 1:5, while T:fM ratio (1:2 to 1:8) was found not to influence binding capacities and imprinting factors (IF). The NIPs showed no preference for either CAF or THP in competitive selectivity studies while MIPs were observed to bind preferentially to their template with THP displaying higher selectivity (72⁻94%) than CAF (63⁻84%). Template selectivity was observed to increase with increasing initiator concentration, with MIPs from I:tM ratio of 1:5 shown to be the most selective towards CAF (84%) and THP (93%). The fM:X ratio only showed minimal effect on MIP selectivity. Overall, for the MIP systems under study, template incorporation, binding capacity, imprinting factor and selectivity are enhanced at a faster rate of polymerisation using an I:tM ratio of 1:5. Polymer particles obtained were between 66 to 140 nm, with MIPs generally smaller than their NIP counterparts, and have been observed to decrease with increasing T:fM and fM:X ratios and increase with increasing initiator concentration.

Polymeric Nanoparticle-Coated Pickering Emulsion-Synthesized Conducting Polyaniline Hybrid Particles and Their Electrorheological Study

To produce an electric stimuli-responsive electrorheological (ER) material, semiconducting core/shell-type polyaniline (PANI) hybrid particles were fabricated through Pickering emulsion-type polymerization, using poly(divinylbenzene-alt-maleic anhydride) (PDVMA) particles as a solid surfactant. The PDVMA nanoparticles were initially polymerized using a self-stable precipitation method. The fabricated PANI/PDVMA composite particles were subjected to various chemical characterizations; further, they were suspended in silicone oil at 10 vol % to prepare an ER fluid, and their viscoelastic behaviors were scrutinized using a rheometer under various input electric fields. We also adopted an LCR meter to evaluate its dielectric characteristics. Our results showed that the PANI/PDVMA composite particles display typical ER performance, such that both dynamic and elastic yield stresses follow a polarization mechanism with a slope of 2.0.

One-step synthesis of poly(ethyleneglycol dimethacrylate)-microspheres-supported nano-Au catalyst in methanol–water solution under γ-ray radiation

Highly-crosslinked poly(ethyleneglycol dimethacrylate) (PEGDMA) microspheres supported nano-Au catalyst (PEGDMA@AuNP) was first prepared through a one-step synthesis method, taking advantage of the γ-ray radiation effect on a simple one-pot system.

Synthesis of conductive magnetic nickel microspheres and their applications in anisotropic conductive film and water treatment

Synthesized conductive magnetic Ni microspheres not only can be used for anisotropic conductive films, but also can be used for rapid waste removal and detoxification extraction with a very simple and efficient procedure.

A green approach to crosslinked polymer microspheres with undoped methacrylate monomers and their potential application as dental restorative materials

Pure polymer microspheres with undoped methacrylate monomers were prepared and firstly applied as organic fillers for dental restorative materials.

An overview of inverted colloidal crystal systems for tissue engineering

Scaffolding is at the heart of tissue engineering but the number of techniques available for turning biomaterials into scaffolds displaying the features required for a tissue engineering application is somewhat limited. Inverted colloidal crystals (ICCs) are inverse replicas of an ordered array of monodisperse colloidal particles, which organize themselves in packed long-range crystals. The literature on ICC systems has grown enormously in the past 20 years, driven by the need to find organized macroporous structures. Although replicating the structure of packed colloidal crystals (CCs) into solid structures has produced a wide range of advanced materials (e.g., photonic crystals, catalysts, and membranes) only in recent years have ICCs been evaluated as devices for medical/pharmaceutical and tissue engineering applications. The geometry, size, pore density, and interconnectivity are features of the scaffold that strongly affect the cell environment with consequences on cell adhesion, proliferation, and differentiation. ICC scaffolds are highly geometrically ordered structures with increased porosity and connectivity, which enhances oxygen and nutrient diffusion, providing optimum cellular development. In comparison to other types of scaffolds, ICCs have three major unique features: the isotropic three-dimensional environment, comprising highly uniform and size-controllable pores, and the presence of windows connecting adjacent pores. Thus far, this is the only technique that guarantees these features with a long-range order, between a few nanometers and thousands of micrometers. In this review, we present the current development status of ICC scaffolds for tissue engineering applications.