Changkui Fu

Thermo and pH Dual-Responsive Materials for Controllable Oil/Water Separation

Thermo and pH dual-controllable oil/water separation materials are successfully fabricated by photo initiated free radical polymerization of dimethylamino ethyl methacrylate (DMAEMA). The PDMAEMA hydrogel coated mesh shows superhydrophilicity and underwater superoleophobicity at certain temperature and pH. Due to the double responsiveness of PDMAEMA hydrogel, the as-prepared mesh can selectively separate water from oil/water mixtures and make water and oil permeate through the mesh orderly and be collected separately by adjusting the temperature or pH. Water can pass through the as-prepared mesh under 55 °C (pH 7) and pH less than 13 (T = 25 °C) while oil is kept on the mesh. When the temperature is above 55 °C or pH is larger than 13, the water retention capacity of PDMAEMA hydrogel is significantly reduced and the swelling volume is decreased. Therefore, oil can permeate through the mesh and be collected in situ. Additionally, this material has excellent potential to be used in practical applications and has created a new field for water/oil separation in which the process can be diversified and more intelligent.

PolyPEGylated nanodiamond for intracellular delivery of a chemotherapeutic drug

Water dispersible and biocompatible polyPEGylated ND nanoparticles were prepared via surface-initiated atom transfer radical polymerization. Cell internalization study reveals that ND nanoparticles facilitate the transport of doxorubicin hydrochloride into A549 cells, indicating their potential applications in cancer therapy.

Selective Photoactivation: From a Single Unit Monomer Insertion Reaction to Controlled Polymer Architectures

Here, we exploit the selectivity of photoactivation of thiocarbonylthio compounds to implement two distinct organic and polymer synthetic methodologies: (1) a single unit monomer insertion (SUMI) reaction and (2) selective, controlled radical polymerization via a visible-light-mediated photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (PET-RAFT) process. In the first method, precise single unit monomer insertion into a dithiobenzoate with a high reaction yield (>97%) is reported using an organic photoredox catalyst, pheophorbide a (PheoA), under red light irradiation (λmax = 635 nm, 0.4 mW/cm(2)). The exceptional selectivity of PheoA toward dithiobenzoate was utilized in combination with another catalyst, zinc tetraphenylporphine (ZnTPP), for the preparation of a complex macromolecular architecture. PheoA was first employed to selectively activate a dithiobenzoate, 4-cyanopentanoic acid dithiobenzoate, for the polymerization of a methacrylate backbone under red light irradiation. Subsequently, metalloporphyrin ZnTPP was utilized to selectively activate pendant trithiocarbonate moieties for the polymerization of acrylates under green light (λmax = 530 nm, 0.6 mW/cm(2)) to yield well-defined graft co-polymers.

A new insight into the Biginelli reaction: the dawn of multicomponent click chemistry?

Looking at ‘old’ reactions from new perspectives sometimes brings new breakthroughs in current hot research areas. We therefore reinvestigated the successful multicomponent reactions (MCRs) in organic chemistry, and are pleased to find the Biginelli reaction, one of the most famous MCRs, has almost all the ‘clickable’ features reported in ‘click chemistry’. The modules of the Biginelli reaction are easily obtained with even more functionalities and diversity, and the reaction can be carried out under mild conditions quickly, compatibly and nearly quantitatively with only water as the byproduct. In current research, the Biginelli reaction has been demonstrated as a new ‘click’ reaction via application in polymer chemistry and chemical biology. Through the modification of polymer chains (side or chain end groups), and the combination with living radical polymerization in a one pot strategy, functional homopolymer and copolymer have been quantitatively prepared, demonstrating the high efficiency and compatibility of the Biginelli reaction in polymer chemistry. Furthermore, we are surprised and excited to find Biginelli reaction can be used as a ‘catalyst free’ bioorthogonal-click reaction to anchor dyes on cell membrane, indicating its possible application in chemical biology. Thus, we address here the ‘clickable’ aspects of the Biginelli reaction, a MCR that is more than 120 years ‘old’. We hope the new insight into the MCRs might bring some new members to the click family as a new type of click reaction: multicomponent click reaction (MCR-Click) which might have potential applications in other areas, such as materials science, polymer chemistry and chemical biology in place of traditional organic chemistry.

Amphiphilic fluorescent copolymers via one-pot combination of chemoenzymatic transesterification and RAFT polymerization: synthesis, self-assembly and cell imaging

The development of fluorescent organic nanoparticles (FONs) based on aggregation induced emission (AIE) dyes has attracted significant research interest in recent years. In this work, a novel one-pot strategy for the fabrication of AIE-based FONs was developed via a combination of RAFT polymerization and enzymatic transesterification for the first time. During this procedure, a hydrophobic tetraphenylethene-functionalized AIE dye (denoted as TPEOH) with a hydroxyl end functional group and a hydrophilic polyethylene glycol monomethyl ether (mPEG-OH, Mn = 350) were simultaneously attached onto the methacrylate monomer via enzymatic transesterification. The amphiphilic copolymer formed after RAFT polymerization of the functionalized methacrylate monomers tended to self-assemble into FONs with the hydrophobic AIE core covered by a hydrophilic PEG shell. The molar fractions of TPE and PEG in the polymer were about 30.5% and 69.5%, respectively, while Mn was 4700 g mol−1 with a narrow polydispersity index (PDI) (∼1.30). The obtained amphiphilic polymer nanoparticles (denoted as TPE-PEG) demonstrated good fluorescence performance and excellent dispersibility in aqueous solution. More importantly, these FONs possessed a spherical morphology with a uniform size (about 200 nm) and excellent biocompatibility, making them promising for bioimaging applications.

Introducing the Ugi reaction into polymer chemistry as a green click reaction to prepare middle-functional block copolymers

Multicomponent reactions (MCRs) and click reactions have a number of significant features in common, such as modularity, high efficiency and atom economy. Some MCRs can thus be considered as a new type of click reaction: a multicomponent click reaction. The well-known Ugi reaction has been utilized as a green click reaction to efficiently stitch two different polymer chains together under very benign conditions (25 °C, catalyst free). Mid-functional block copolymers and miktoarm star copolymers which are normally difficult to synthesize have thus been easily prepared, indicating the promising potential of the Ugi reaction in polymer chemistry to prepare sophisticated structural copolymers.

The power of one-pot: a hexa-component system containing π–π stacking, Ugi reaction and RAFT polymerization for simple polymer conjugation on carbon nanotubes

A hexa-component system has been successfully developed for simple polymer conjugation on carbon nanotubes. The well-known Ugi reaction has been recognized as a multicomponent click (MCC) reaction to efficiently collaborate with π–π stacking and RAFT polymerization to construct this delicate one-pot system. The CNT–(co)polymer composites inherit the properties of the conjugated polymers and can be well dispersed in both organic and aqueous solvents. As a simple and efficient method, this one-pot system might have the potential to be a general approach to prepare carbon-based composites.

The Ugi reaction in polymer chemistry: syntheses, applications and perspectives

The Ugi reaction, one of the most famous multicomponent reactions, has recently been introduced into polymer chemistry as a novel, efficient and useful tool to prepare multifunctional polymers. In this review, the recent progress on the utilization of the Ugi reaction in polymer chemistry, including monomer synthesis, polycondensation, post-polymerization modification (PPM) etc. has been summarized. Meanwhile, the applications of the multifunctional polymers synthesized via the Ugi reaction and the future development of the Ugi reaction in polymer chemistry have also been discussed.

Synthesis of Discrete Oligomers by Sequential PET‐RAFT Single‐Unit Monomer Insertion

Uniform synthetic polymers with precisely defined molar mass and monomer sequence (primary structure) have many potential high-value applications. However, a robust and versatile synthetic strategy for these materials remains one of the great challenges in polymer synthesis. Herein we describe proof-of-principle experiments for a modular strategy to produce discrete oligomers by a visible-light-mediated radical chain process. We utilize the high selectivity provided by photo-induced electron/energy transfer (PET) activation to develop efficient single unit monomer insertion (SUMI) into reversible addition-fragmentation chain-transfer (RAFT) agents. A variety of discrete oligomers (single unit species, dimers, and, for the first time, trimers) have been synthesized by sequential SUMI in very high yield under mild reaction conditions. The trimers were used as building blocks for the construction of uniform hexamers and graft copolymers with precisely defined branches.

A multicomponent polymerization system: click–chemoenzymatic–ATRP in one-pot for polymer synthesis

A simultaneous multicomponent polymerization (MCP) system combining copper(I) catalyzed azide alkyne cycloaddition (CuAAC, ‘Click’ reaction), enzymatic transesterification and atom transfer radical polymerization (ATRP) has been successfully developed.