Assessment of Microwave Effect on Polymerization Conducted under ARGET ATRP Conditions

Effect of Microwave-Assisted Curing on Properties of Waterborne Silicone Antifouling Coatings

Waterborne silicone coatings are prepared in this paper by using silicone emulsion as a film-forming material, γ-methacryloxypropyltrimethoxysilane, and dibutyltin dilaurate as a curing agent and a catalyst, respectively. The corresponding coatings are obtained by controlling different microwave times to accelerate the coating curing. The surface morphology, roughness, surface properties, mechanical properties, and antifouling properties of the coating are studied by laser confocal microscope, contact angle measurement, tensile test, marine bacterial attachment test, and benthic diatom adhesion test. Additionally, the action mechanism of microwaves in the curing process of the coatings is also discussed. The results show that the microwave can greatly reduce the curing time of waterborne silicone coating. It can improve the painting efficiency, the surface roughness of the coating, and the mechanical properties of the coatings. The change in roughness increases the contact angle of the coating, reduces the apparent surface energy, and then improves the antifouling performance. For the coating cured by microwave, with the increase in microwave curing time, the water and diiodomethane contact angles of the coating gradually increase, and the surface energy gradually decreases from about 20 mJ/m2 to 10.8 mJ/m2. With the increase in microwave time, the attachment amount of Navicular Tenera gradually decreases, the removal rate gradually increases, and the removal rate of Navicular Tenera in the coating increases from 15.36% to 31.78%. The bacterial removal rate of the coating can be increases from 11.05% to 22.28% after microwave curing. Microwave-assisted curing is helpful in improving the antifouling and self-cleaning performance of waterborne silicone coatings, showing promising potential applications.

Surface Modifications of Poly(Ether Ether Ketone) via Polymerization Methods-Current Status and Future Prospects

Surface modification of poly(ether ether ketone) (PEEK) aimed at applying it as a bone implant material aroused the unflagging interest of the research community. In view of the development of implantology and the growing demand for new biomaterials, increasing biocompatibility and improving osseointegration are becoming the primary goals of PEEK surface modifications. The main aim of this review is to summarize the use of polymerization methods and various monomers applied for surface modification of PEEK to increase its bioactivity, which is a critical factor for successful applications of biomedical materials. In addition, the future directions of PEEK surface modifications are suggested, pointing to low-ppm surface-initiated atom transfer radical polymerization (SI-ATRP) as a method with unexplored capacity for flat surface modifications.

Role of External Field in Polymerization: Mechanism and Kinetics

The past decades have witnessed an increasing interest in developing advanced polymerization techniques subjected to external fields. Various physical modulations, such as temperature, light, electricity, magnetic field, ultrasound, and microwave irradiation, are noninvasive means, having superb but distinct abilities to regulate polymerizations in terms of process intensification and spatial and temporal controls. Gas as an emerging regulator plays a distinctive role in controlling polymerization and resembles a physical regulator in some cases. This review provides a systematic overview of seven types of external-field-regulated polymerizations, ranging from chain-growth to step-growth polymerization. A detailed account of the relevant mechanism and kinetics is provided to better understand the role of each external field in polymerization. In addition, given the crucial role of modeling and simulation in mechanisms and kinetics investigation, an overview of model construction and typical numerical methods used in this field as well as highlights of the interaction between experiment and simulation toward kinetics in the existing systems are given. At the end, limitations and future perspectives for this field are critically discussed. This state-of-the-art research progress not only provides the fundamental principles underlying external-field-regulated polymerizations but also stimulates new development of advanced polymerization methods.

Natural catalyst mediated ARGET and SARA ATRP of N-isopropylacrylamide and methyl acrylate

An extract prepared from inexpensive, drumstick leaves having natural transition metals in ppm levels was exploited as a catalyst for a well-controlled synthesis of poly(N-isopropylacrylamide) and poly(methyl acrylate).

ARGET ATRP of Triblock Copolymers (PMMA-b-PEO-b-PMMA) and Their Microstructure in Aqueous Solution

Triblock copolymers poly(methyl methacrylate)-b-poly(ethylene oxide)-b-poly(methyl methacrylate) (PMMA-b-PEO-b-PMMA) with designed molecular weight of PMMA and PEO blocks were synthesized via the activator regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP) of MMA. The Br-terminated Br-PEO-Br with the molecular weights of 20k and 100k were used as  macroinitiators. ARGET ATRP was performed with ppm level amount CuBr2 as the catalyst and ascorbic acid as the reducing agent to overcome the sensitivity to oxygen in a traditional ATRP. The molecular weight of the PMMA block was manipulated by changing the molar ratio of monomers to the Br-PEO-Br macroinitiators. The synthesis of PMMA-b-PEO-b-PMMA and its structure was confirmed by Fourier transform infrared and 1H NMR, and the molecular weight of the PMMA block was determined by 1H NMR. Aqueous solutions of PMMA-b-PEO-b-PMMA were prepared by solvent-exchange, and their microstructures were examined by tensiometry, static light scattering, and transmission electron microscopy. The effects of molecular weight of the PMMA and PEO blocks on the microstructure were elucidated.