End-functionalized polymers by controlled/living radical polymerizations: synthesis and applications

This review focuses on end-functionalized polymers synthesized by controlled/living radical polymerizations and the applications in fields including bioconjugate formation, surface modification, topology construction, and self-assembly.

A two-phase bromination process using tetraalkylammonium hydroxide for the practical synthesis of α-bromolactones from lactones

A simple and efficient method for α-brominating lactones that affords α-bromolactones under mild conditions using tetraalkylammonium hydroxide (R₄N⁺OH^-) as a base was developed. Lactones are ring-opened with Br₂ and a substoichiometric amount of PBr₃, leading to good yields of the corresponding α-bromocarboxylic acids. Subsequent intramolecular cyclization over 1 h using a two-phase system (H₂O/CHCl₃) containing R₄N⁺OH^- afforded α-bromo lactones in good yields. This method can be applied at the 10 mmol scale using simple operations. α-Bromo-δ-valerolactone, which is extremely reactive and difficult to isolate, could be isolated and stored in a freezer for about one week using the developed method. Optimizing the solvent for environmentally friendly large-scale syntheses revealed that methyl ethyl ketone (MEK) was as effective. In addition, in situ-generated α-bromo-δ-valerolactone was directly converted into a sulfur-substituted functional lactone without difficulty by reacting it with a sulfur nucleophile in one pot without isolation. This new bromination system is expected to facilitate the industrial use of α-bromolactones as important intermediates.

Recent advances on porous interfaces for biomedical applications

Porous structures on solid surfaces prepared artificially through the water droplet template method have the features of easy operation, low cost and self-removal of templates, and thus are widely applied in the fields of medicine, biomedicine, adsorption, catalysis, and separation, optical and electronic materials. Due to their tunable dimensions, abundant selection of materials, mechanical stability, high porosity, and enlarged pore surface, the formed porous interfaces show specific significance in bio-related systems. In this study, recent achievements related to applications of porous interfaces and a focus into biological and medical-related systems are summarized. The discussion involves the preparation of porous interfaces, and porous interface-induced cell behaviors including culture, growth, proliferation, adhesion, and differentiation of cells. The inhibitory effect of bacteria and separated features of microorganisms supported by porous interfaces, the immobilization of biomolecules related to proteins, DNA and enzymes, and the controllable drug delivery are also discussed. The summary of recent advances pointed out in the study, are suggestive of insights for motivating unique potential applications including their extension to porous interfaces in biomedical materials.

In Search of a Green Process: Polymeric Films with Ordered Arrays via a Water Droplet Technique

As an efficient technique for the preparation of polymeric hexagonal orderly arrays, the breath figure (BF) process has opened a modern avenue for a bottom-up fabrication method for more than two decades. Through the use of the water vapor condensation on the solution surface, the water droplets will hexagonally pack into ordered arrays, acting as a template for controlling the regular micro patterns of polymeric films. Comparing to the top-down techniques, such as lithography or chemical etching, the use of water vapor as the template provides a simple fabrication process with sustainability. However, using highly hazardous solvents such as chloroform, carbon disulfide (CS2), benzene, dichloromethane, etc., to dissolve polymers might hinder the development toward green processes based on this technique. In this review, we will touch upon the contemporary techniques of the BF process, including its up-to-date applications first. More importantly, the search of greener processes along with less hazardous solvents for the possibility of a more sustainable BF process is the focal point of this review.

Designing 3D Biological Surfaces via the Breath-Figure Method

The fabrication of biointerfaces that mimic cellular physiological environments is critical to understanding cell behaviors in vitro and for the design of tissue engineering. Breath figure is a self-assemble method that uses water droplets condensed from moisture as template and ends up with a highly ordered hexagonal pore array; this approach is used to fabricate various biological substrates. This progress report provides an overview of strategies to achieve topographical modifications and chemical-patterned arrays, such as modulation of the pore size, shape and selective decoration of the honeycomb holes. Using recent results in the biological fields, potential future applications and developments of honeycomb structures are commented upon.

Synthesis of novel guanidine-based ABA triblock copolymers and their antimicrobial honeycomb films

Novel antimicrobial poly(methacryl guanidine hydrochloride)-block-polystyrene-block-poly(methacryl guanidine hydrochloride) triblock copolymers were synthesizedviaRAFT polymerization and fabricated into antimicrobial honeycomb films.

Dynamic effects and adhesion of water droplet impact on hydrophobic surfaces: bouncing or sticking

This work reported the dynamic effects of water droplet impact on flat, porous and pincushion structure films of star shaped polyhedral oligomeric silsesquioxane (POSS) fluorinated acrylates, POSS-poly(trifluoroethyl methacrylate)₈ (POSS-(PTFEMA)₈) and POSS-(poly(trifluoroethyl methacrylate)-b-poly(methyl methacrylate))₈ (POSS-(PTFEMA-b-PMMA)₈), using the breath figure method. The porous and pincushion structure films with different surface chemical compositions were obtained by controlling the copolymer structure and temperature and by stripping of the surface. The water contact angles on the different films were measured, and the water droplets on the pincushion structure films when reversed at 45°, 90°, 135° and 180° were also studied. It was found that the pincushion structure films revealed a water adhesion ability. Furthermore, the water droplet impact behavior on these films was investigated. The morphology variations of water droplets, spreading diameter of the droplets, energy conversion, restitution coefficient and adhesion force were examined. Finally, the schematic illustration of water droplets under the static and dynamic states in contact with the pincushion and porous structure surfaces was proposed. It is critical to materialize various applications such as microdroplet transportation, soil erosion, spray painting, anti-icing surface and antifouling agents for textiles.

Synthesis of diblock copolymer nano-assemblies by PISA under dispersion polymerization: comparison between ATRP and RAFT

PHPMA-b-PBzMA diblock copolymer nano-assemblies were synthesized by ATRP dispersion polymerization and were compared with those obtained by RAFT dispersion polymerization.

Synthesis of diverse α,ω-telechelic polystyrenes with di- and tri-functionality via tandem or one-pot strategies combining aminolysis of RAFT-polystyrene and a thiol–ene “click” reaction

Diverse new α,ω-telechelic polystyrenes with di-/tri-functionality were synthesized via tandem/one-pot strategies combining aminolysis of RAFT-polystyrene and a thiol–ene “click” reaction.

Porphyrinated polyimide honeycomb films with high thermal stability for HCl gas sensing

Thermally stable films with ordered pores are fabricated from porphyrinated polyimides and they exhibit excellent property in HCl gas sensing.

Honeycomb porous films of pentablock copolymer on liquid substrates via breath figure method and their hydrophobic properties with static and dynamic behaviour

The peeled film obtained on the isopropanol substrate through breath figure method exhibits the best hydrophobic properties, and the water droplet impact behavior shows an obvious rebound tendency and a weak maximum spreading diameter.

Fabrication of perforated isoporous membranes via a transfer-free strategy: enabling high-resolution separation of cells

Thin perforated membranes with ordered pores are ideal barriers for high-resolution and high-efficiency selective transport and separation of biological species. However, for self-assembled thin membranes with a thickness less than several micrometers, an additional step of transferring the membranes onto porous supports is generally required. In this article, we present a facile transfer-free strategy for fabrication of robust perforated composite membranes via the breath figure process, and for the first time, demonstrate the application of the membranes in high-resolution cell separation of yeasts and lactobacilli without external pressure, achieving almost 100% rejection of yeasts and more than 70% recovery of lactobacilli with excellent viability. The avoidance of the transfer step simplifies the fabrication procedure of composite membranes and greatly improves the membrane homogeneity. Moreover, the introduction of an elastic triblock copolymer increases the interfacial strength between the membrane and the support, and allows the preservation of composite membranes in a dry state. Such perforated ordered membranes can also be applied in other size-based separation systems, enabling new opportunities in bioseparation and biosensors.

Synthesis of core cross-linked star polystyrene with functional end groups and self-assemblies templated by breath figures

We report the synthesis of core cross-linked star (CCS) polymers with functional end groups for self-assembled films, which show mono-layer and multi-layer transition, depending on arm numbers, arm length, and end groups.

Polystyrene with hydrophobic end groups: synthesis, kinetics, interfacial activity, and self-assemblies templated by breath figures

Polystyrenes with hydrophobic end groups are synthesized from a series of alkyl or fluorinated ATRP initiators to fine-tune the surface morphologies of honeycomb films prepared by the breath figure method.