Preparation of Block Copolymer Self-Assemblies via Pisa in a Non-Polar Medium Based on RCMP

Polymerization-induced self-assembly (PISA) is conducted in a non-polar medium (n-dodecane) via reversible complexation-mediated polymerization (RCMP). Stearyl methacrylate (SMA) is used to synthesize a macroinitiator, and subsequent block polymerization of benzyl methacrylate (BzMA) from the macroinitiator in n-dodecane afforded a PSMA-PBzMA block copolymer, where PSMA is poly(stearyl methacrylate) and PBzMA is poly(benzyl methacrylate). Because PSMA is soluble but PBzMA is insoluble in n-dodecane, the block copolymer formed a self-assembly during the block polymerization (PISA). Spherical micelles, worms, and vesicles are obtained, depending on the degrees of polymerization of PSMA and PBzMA. "One-pot" PISA is also attained; namely, BzMA is directly added to the reaction mixture of the macroinitiator synthesis, and PISA is conducted in the same pot without purification of the macroinitiator. The spherical micelle and vesicle structures are also fixed using a crosslinkable monomer during PISA. RCMP-PISA is highly attractive as it is odorless and metal-free. The "one-pot" synthesis does not require the purification of the macroinitiator. RCMP-PISA can provide a practical approach to synthesize self-assemblies in non-polar media.

Self-catalyzed synthesis of a nano-capsule and its application as a heterogeneous RCMP catalyst and nano-reactor

A nano-capsule synthesized via self-catalyzed RCMP and its use as a heterogeneous catalyst and a nano-reactor of RCMP to generate a multi-elemental particle.

Encapsulation of volatile compounds in liquid media: Fragrances, flavors, and essential oils in commercial formulations

The first marketed example of the application of microcapsules dates back to 1957. Since then, microencapsulation techniques and knowledge have progressed in a plethora of technological fields, and efforts have been directed toward the design of progressively more efficient carriers. The protection of payloads from the exposure to unfavorable environments indeed grants enhanced efficacy, safety, and stability of encapsulated species while allowing for a fine tuning of their release profile and longer lasting beneficial effects. Perfumes or, more generally, active-loaded microcapsules are nowadays present in a very large number of consumer products. Commercial products currently make use of rigid, stable polymer-based microcapsules with excellent release properties. However, this type of microcapsules does not meet certain sustainability requirements such as biocompatibility and biodegradability: the leaking via wastewater contributes to the alarming phenomenon of microplastic pollution with about 4% of total microplastic in the environment. Therefore, there is a need to address new issues which have been emerging in relation to the poor environmental profile of such materials. The progresses in some of the main application fields of microencapsulation, such as household care, toiletries, cosmetics, food, and pesticides are reviewed herein. The main technologies employed in microcapsules production and the mechanisms underlying the release of actives are also discussed. Both the advantages and disadvantages of every technique have been considered to allow a careful choice of the most suitable technique for a specific target application and prepare the ground for novel ideas and approaches for encapsulation strategies that we expect to be proposed within the next years.

Synthesis of uniform submicron poly(lactic acid)-based particles/capsules by radical precipitation polymerization

Poly(l-lactic acid) (PLLA) is a well-known biopolymer, usually synthesized via step-growth or ring-opening polymerization from lactic acid or a lactide monomer, respectively. PLLA microspherical particles are produced by dispersion polymerization with a ring-opening lactide monomer using a particular copolymer chain as a stabilizer. This is not easy to achieve when dehydration is needed. Here, a robust and simple synthesis of a nearly monodisperse, submicron PLLA-based particle/capsule was proposed via radical precipitation polymerization without the use of surfactant. A commercial PLLA was first glycolyzed with ethylene glycol to obtain a low molecular weight glycolyzed PLLA (GPLLA). Then, the GPLLA was copolymerized with methacrylic acid and ethylene glycol dimethacrylate monomers using a benzoyl peroxide initiator. Active sites on the GPLLA backbone were generated by hydrogen abstraction of benzoyloxy radicals that further copolymerized before self-assembly to form the polymer particles. Uniform particle size of about 580 nm with a low polydispersity index (PDI) of 0.012 was obtained. This method was also implemented to produce nearly monodisperse capsules containing linalool. The particle size of PLLA-based capsules was about 280 nm with narrow particle size distribution (PDI of 0.120). The PLLA-based capsules effectively inhibited microbial growth of Staphylococcus aureus, Escherichia coli and Candida albicans and were not toxic to human cells.

Synthesis of core-crosslinked star polymers via organocatalyzed living radical polymerization

Core-crosslinked star polymers synthesized via a grafting-through approach using RCMP.

Reduction-responsive double hydrophilic block copolymer nano-capsule synthesized via RCMP-PISA

Double hydrophilic block copolymer vesicles synthesized via RCMP-PISA are degradable under a reductive conditions.

Forced gradient copolymerisation: a simplified approach for polymerisation-induced self-assembly

In this work, a novel and versatile gradient copolymerisation approach to simplify polymeric nanoparticle synthesis through polymerisation-induced self-assembly (PISA) is reported.

Aqueous emulsion polymerizations of methacrylates and styrene via reversible complexation mediated polymerization (RCMP)

Aqueous emulsion polymerization via reversible complexation mediated living radical polymerization yielded low-dispersity poly(methyl methacrylate)s and polystyrenes.

Dual Role of Doxorubicin for Photopolymerization and Therapy

In this study, we report dual roles for doxorubicin (DOX), which can serve as an antitumor drug as well as a cocatalyst for a photoliving radical polymerization. DOX enhances the polymerization rates of a broad range of monomers, including acrylamide, acrylate, and methacrylates, allowing for high monomer conversion and well-defined molecular weights under irradiation with a blue light-emitting diode light (λ_max = 485 nm, 2.2 mW/cm²). Utilizing this property, the photopolymerization of N,N-diethylacrylamide was performed in the presence of a poly(oligo(ethylene glycol) methyl ether acrylate) macroreversible addition-fragmentation chain transfer (macroRAFT) agent to prepare polymeric nanoparticles via aqueous polymerization-induced self-assembly (PISA). By varying the monomer:macroRAFT ratio, spherical polymeric nanoparticles of various diameters could be produced. Most notably, DOX was successfully encapsulated into the hydrophobic core of nanoparticles during the PISA process. The DOX-loaded nanoparticles were effectively uptaken into tumor cells and significantly inhibited the proliferation of tumor cells, demonstrating that the DOX bioactivity was not affected by the polymerization reaction.

Recent development in halogen-bonding-catalyzed living radical polymerization

The development and applications of an organocatalyzed living radical polymerization via halogen-bonding catalysis, i.e., reversible complexation mediated polymerization (RCMP), are highlighted.