Mechanism of ε-caprolactone polymerization in the presence of alkali metal salts: investigation of initiation course and determination of polymers structure by MALDI-TOF mass spectrometry

Recent Advances in Polycaprolactones for Anticancer Drug Delivery

Poly(ε-Caprolactone)s are biodegradable and biocompatible polyesters that have gained considerable attention for drug delivery applications due to their slow degradation and ease of functionalization. One of the significant advantages of polycaprolactone is its ability to attach various functionalities to its backbone, which is commonly accomplished through ring-opening polymerization (ROP) of functionalized caprolactone monomer. In this review, we aim to summarize some of the most recent advances in polycaprolactones and their potential application in drug delivery. We will discuss different types of polycaprolactone-based drug delivery systems and their behavior in response to different stimuli, their ability to target specific locations, morphology, as well as their drug loading and release capabilities.

Recent Advances in Lignocellulose-Based Monomers and Their Polymerization

Replacing fossil-based polymers with renewable bio-based polymers is one of the most promising ways to solve the environmental issues and climate change we human beings are facing. The production of new lignocellulose-based polymers involves five steps, including (1) fractionation of lignocellulose into cellulose, hemicellulose, and lignin; (2) depolymerization of the fractionated cellulose, hemicellulose, and lignin into carbohydrates and aromatic compounds; (3) catalytic or thermal conversion of the depolymerized carbohydrates and aromatic compounds to platform chemicals; (4) further conversion of the platform chemicals to the desired bio-based monomers; (5) polymerization of the above monomers to bio-based polymers by suitable polymerization methods. This review article will focus on the progress of bio-based monomers derived from lignocellulose, in particular the preparation of bio-based monomers from 5-hydroxymethylfurfural (5-HMF) and vanillin, and their polymerization methods. The latest research progress and application scenarios of related bio-based polymeric materials will be also discussed, as well as future trends in bio-based polymers.

Biocatalytic Approach for Novel Functional Oligoesters of ε-Caprolactone and Malic Acid

Biocatalysis has developed in the last decades as a major tool for green polymer synthesis. The particular ability of lipases to catalyze the synthesis of novel polymeric materials has been demonstrated for a large range of substrates. In this work, novel functional oligoesters were synthesized from ε-caprolactone and D,L/L-malic acid by a green and sustainable route, using two commercially available immobilized lipases as catalysts. The reactions were carried out at different molar ratios of the comonomers in organic solvents, but the best results were obtained in solvent-free systems. Linear and cyclic oligomeric products with average molecular weights of about 1500 Da were synthesized, and the formed oligoesters were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. The oligoester synthesis was not enantioselective in the studied reaction conditions. The operational stability of both biocatalysts (Novozyme 435 and GF-CalB-IM) was excellent after reutilization in 13 batch reaction cycles. The thermal properties of the reaction products were investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis. The presence of polar pendant groups in the structure of these oligomers could widen the possible applications compared to the oligomers of ε-caprolactone or allow the conversion to other functional materials.

Liquid Metal Initiator of Ring-Opening Polymerization: Self-Capsulation into Thermal/Photomoldable Powder for Multifunctional Composites

Liquid metal nanodroplets not only share similar metallic properties and nanoscale effect with solid metal nanoparticles, but also possess the additional uniqueness in nonvolatile fluidity and ambient sintering ability into continuous conductors. In most cases, liquid metal nanodroplets are encapsulated into ultrathin and fragile shells of oxides and amphiphile monolayers, and may be hindered from incorporating homogeneously into various composites through conventional processing methods. In this study, ring-opening polymerization is found to be initiated by sonicating the liquid metal EGaIn in fluidic lactones. By this in situ polymerization, EGaIn nanodroplets are encapsulated into polylactone shells with tunable thickness, which can further be dried into a solid powder. Besides high chemical stability and dispersibility in organic solvents, the powder of the EGaIn capsules combines the exceptional properties of the EGaIn droplets (e.g., photothermal effect) and the polylactone shells (e.g., biocompatibility, biodegradability, and compatibility with different polymer matrixes), being capable of being introduced into thermoplastic composites through liquid casting and thermal- or photomolding for the notch-insensitive tearing property, sintering-induced electric conductivity, and photothermal effect. Thus, the EGaIn initiator of ring-opening polymerization may start a pathway to produce stable andthermal/photomoldable powders of EGaIn capsules and their multifunctionalcomposites, applicable in biomedicines, soft electronics, and smart robots.