Yuewen Yu

Bio: Yuewen Yu is an academic researcher from Nankai University. The author has contributed to research in topics: Polymerization & Chain transfer. The author has an hindex of 1, co-authored 2 publications receiving 1 citations.

Synthesis of <scp>Stimuli‐Responsive</scp> Block Copolymers and Block Copolymer Nano‐assemblies

Abstract: Block copolymers have aroused much interest, and their application has been rapidly expanded. In recent years, our group has committed to exploring synthesis and self-assembly of block copolymers. We have designed and synthesized several new thermo-responsive polymers and photo-responsive polymers by living/controlled radical polymerization (LCRP) and investigated their stimuli-responsive properties. Aiming at convenient and efficient synthesis of block copolymer nano-assemblies, we have developed several methods based on polymerization-induced self-assembly (PISA). Herein, we give a short summary of our research in these years. The aim of this account is to stimulate innovative synthesis strategies of block copolymer nano-assemblies, and promote more scientific research cooperation to face the exciting opportunities and challenges encountered in block copolymers. What is the most favorite and original chemistry developed in your research group? Thermo-responsive polymers based on dialkylamine groups may be the such thing. It is found that the dialkylamine groups especially the diethylamine group act the predominant role to the thermo-response, and based on this finding several new thermo-responsive polymers and stimuli-responsive block copolymer nano-assemblies have been synthesized. How do you get into this specific field? Could you please share some experiences with our readers? Since 2004 I got Ph.D. degree in polymer chemistry and physics from Nankai University, I began my research mainly on polymer chemistry till now. I think it the most important to focus on a topic useful in science or in practical application, which helps to maintain interest continuously. How do you supervise your students? It is a good way to discuss with students timely and deeply. What is the most important personality for scientific research? Hard work and keen interest. What are your hobbies? What's your favorite book(s)? I like flower farming and fishing. When I retire, I think I will be a good farmer. Who influences you mostly in your life? My parents. They are simple, kind hearted and hardworking.

Stimuli-sensitivity and dynamics in the self-assembly structure of TEMPO-containing nonamphiphilic nanoparticles and their triggering hydrophobic drug release

Abstract: Understanding the dynamics of stimuli-sensitive self-assembled nanomaterials is crucial for their potential applications, however, it is relatively difficult to quantitatively probe the dynamics using conventional analytical techniques because of the low sensitivity and selectivity of these techniques. In this research, TEMPO-containing nonamphiphilic copolymers are synthesized and highly sensitive, selective and non-destructive electron spin resonance (ESR) spectroscopy is applied to study their dynamics in stimuli-sensitive self-assembled nanostructures in different microenvironments. ESR spectroscopy reveals the structural changes of the smart supramolecular nanoparticles (SNPs) in their controlled assemblies by observing the molecular-level interactions. In order to obtain the dynamical evidence, several spectroscopic parameters such as rotational correlation time, hyperfine splitting constant, intensity increase/decrease and anisotropy parameters are determined from the ESR spectra. The stimuli-sensitivity and dynamics strongly depend on the SNPs’ microenvironment correlated to several chemical and physiological parameters such as radical concentration, pH, redox agent, temperature, polarity and viscosity. The results provide quantitative insights into the interface of the supramolecular assemblies. The nanoparticles showed good biocompatibility confirmed by the hemolysis test and the MTT assay. Furthermore, proof-of-concept experiments were carried out to demonstrate the SNPs’ stimuli-sensitive performance as a hydrophobic anticancer drug nanocarrier. This effort can be used to design other colloidal nano-platforms for the potential application in cancer treatment.

Formation of n-Hexane-in-DMF Nonaqueous Pickering Emulsions: ABC Triblock Worms versus AB Diblock Worms.

Abstract: Nonaqueous Pickering emulsions exhibit promising applications in many industrial areas but have been relatively less studied in the past. In this study, n-hexane-in-DMF nonaqueous Pickering emulsions stabilized by core cross-linked copolymer worms with mixed shells are demonstrated for the first time. Core cross-linked copolymer worms with mixed shells were prepared by seeded reversible addition-fragmentation chain transfer (RAFT) quasi-solution polymerization. Specifically, polystyrene-poly(4-vinylpyridine) (PS-P4VP) diblock copolymer worms were first prepared via RAFT-mediated dispersion polymerization in toluene under the given conditions using PS as both the macro-CTA and the stabilizer block. After the chemical cross-linking of P4VP cores, PS-P4VP diblock copolymer worms were chain-extended with LMA in DMF/toluene (1:9, weight ratio) mixed solvents, producing core cross-linked PS-P4VP-PLMA worms with PS/PLMA mixed shells. The as-prepared core cross-linked PS-P4VP-PLMA worms with mixed PS/PLMA shells were further utilized as Pickering emulsifiers for the generation of nonaqueous n-hexane-in-DMF Pickering emulsions. The emulsifying performances of mixed-shell copolymer worms were compared with those of their spherical and linear analogues with entirely identical chemical compositions as well as PS-P4VP diblock copolymer worm precursors, respectively.