Progress in the Free and Controlled Radical Homo- and Co-Polymerization of Itaconic Acid Derivatives: Toward Functional Polymers with Controlled Molar Mass Distribution and Architecture

Polymeric derivatives of itaconic acid are becoming increasingly more interesting for research and industry because itaconic acid is accessible from renewable resources. In spite of the structural similarity of poly(itaconic acid derivatives) to poly(methacrylates), they are much less reactive, homopolymerize only sluggishly by free radical polymerization (FRP), and are often obtained with low molar masses and conversions. This has so far limited their use. The reasons for the low reactivity of itaconic acid derivatives (including itaconimides, diitaconates, and diitaconamides) are combined steric and electronic effects, as demonstrated by the body of literature on the FRP homopolymerization kinetics of these monomers which is summarized herein. These problems can be solved to a large extent by using controlled radical polymerization (CRP) techniques, notably atom transfer radical polymerization (ATRP) and reversible addition and fragmentation chain transfer radical polymerization (RAFT). By optimizing the reaction conditions for the ATRP and RAFT of itaconic acid derivatives, in particular the reaction temperature, linear relations between molar mass and conversion are obtained in many cases, and homopolymers with high molar masses and reasonably narrow polydispersity indices become accessible. This review presents the state-of-the-art FRP and CRP of itaconic acid derivatives, and highlights functional polymers obtained by these methods.

Fabrication of claviform fluorescent polymeric nanomaterials containing disulfide bond through an efficient and facile four-component Ugi reaction

Multicomponent reactions (MCRs) have attracted broad interest for preparation of functional nanomaterials especially for the synthesis of functional polymers. Herein, we utilized an "old" MCR, the four-component Ugi reaction, to synthesize disulfide bond containing poly(PEG-TPE-DTDPA) amphiphilic copolymers with aggregation-induced emission (AIE) feature. This four-component Ugi reaction was carried out under rather mild reaction conditions, such as room temperature, no gas protection and absent of catalysts. The amphiphilic poly(PEG-TPE-DTDPA) copolymers with high number-average molecular weight (up to 86,440 Da) can self-assemble into claviform fluorescent polymeric nanoparticles (FPNs) in aqueous solution, and these water-dispersed nanoparticles exhibited strong emission, large Stokes shift (142 nm), low toxicity and remarkable ability in cellular imaging. Moreover, owing to the introduction of 3,3'-dithiodipropionic acid with disulfide bond, the resultant AIE-active poly(PEG-TPE-DTDPA) could display reduction-responsiveness and be utilized for synthesis of photothermal agents in-situ. Therefore, the AIE-active poly(PEG-TPE-DTDPA) could be promising for controlled intracellular delivery of biological activity molecules and fabrication of multifunctional AIE-active materials. Therefore, these novel AIE-active polymeric nanoparticles could be of great potential for various biomedical applications, such as biological imaging, stimuli-responsive drug delivery and theranostic applications.

Recent development and prospects of surface modification and biomedical applications of MXenes

MXenes, as a novel kind of two-dimensional (2D) materials, were first discovered by Gogotsi et al. in 2011. Owing to their multifarious chemical compositions and outstanding physicochemical properties, the novel types of 2D materials have attracted intensive research interest for potential applications in various fields such as energy storage and conversion, environmental remediation, catalysis, and biomedicine. Although many achievements have been made in recent years, there still remains a lack of reviews to summarize these recent advances of MXenes, especially in biomedical fields. Understanding the current status of surface modification, biomedical applications and toxicity of MXenes and related materials will give some inspiration to the development of novel methods for the preparation of multifunctional MXene-based materials and promote the practical biomedical applications of MXenes and related materials. In this review, we present the recent developments in the surface modification of MXenes and the biomedical applications of MXene-based materials. In the first section, some typical surface modification strategies were introduced and the related issues were also discussed. Then, the potential biomedical applications (such as biosensor, biological imaging, photothermal therapy, drug delivery, theranostic nanoplatforms, and antibacterial agents) of MXenes and related materials were summarized and highlighted in the following sections. In the last section, the toxicity and biocompatibility of MXenes in vitro were mentioned. Finally, the development, future directions and challenges about the surface modification of MXene-based materials for biomedical applications were discussed. We believe that this review article will attract great interest from the scientists in materials, chemistry, biomedicine and related fields and promote the development of MXenes and related materials for biomedical applications.

Surface-grafted polyacrylonitrile brushes with aggregation-induced emission properties

Polyacrylonitrile (PAN) brushes were grafted from silicon wafers by photoinduced ATRP and shown to exhibit aggregation-induced emission (AIE) properties.

Photoregulated reversible addition–fragmentation chain transfer (RAFT) polymerization

Different strategies on photoregulated RAFT polymerization are developed. This minireview summarizes recent advances in photoregulated RAFT polymerization and its applications.

Preparation of semifluorinated poly(meth)acrylates by improved photo-controlled radical polymerization without the use of a fluorinated RAFT agent: facilitating surface fabrication with fluorinated materials

Semifluorinated poly(meth)acrylates are prepared under both organocatalyzed and catalyst-free photo-controlled radical polymerization conditions from simple RAFT agents.

Cross-linked AIE supramolecular polymer gels with multiple stimuli-responsive behaviours constructed by hierarchical self-assembly

Cross-linked AIE supramolecular polymer gels were successfully constructed by hierarchical self-assembly.