Activation and Deactivation of Chirality Transfer in the Superbundles of Sequence-defined Stereoisomers.

Discrete oligomers can be used to precisely evaluate the structure-property relationship and enable unique chiroptical activities, however, the role of stereochemical sequences on chirality transfer is still unclear. Herein, we report the successful synthesis of a series of sequence-defined chiral azobenzene (Azo) oligomers via iterative stepwise chain growth strategy. Sequence-defined stereoisomers with one single chiral (L or D) stereocenter at the α-position, ω-position and middle- (m-) position have completely different self-assembly dynamics.

Self-promoted Controlled Ring-opening Polymerization via Side Chain-mediated Proton Transfer for the Synthesis of Tertiary Amine-pendant Polypeptoids.

Proton transfer is essential in virtually all biochemical processes, with enzymes facilitating this transfer by optimizing the proximity and orientation of reactants through site-specific hydrogen bonds. Proton transfer is also crucial in the rate-determining step for the ring-opening polymerization of N-carboxyanhydrides (NCAs), widely used to prepare various peptidomimetic materials. This study utilizes side chain-assisted strategy to accelerate the rate of chain propagation by using NCAs with tertiary amine pendants.

ROS-sensitive PD-L1 siRNA cationic selenide nanogels for self-inhibition of autophagy and prevention of immune escape.

In the field of cancer therapy, inhibiting autophagy has emerged as a promising strategy. However, pharmacological disruption of autophagy can lead to the upregulation of programmed death-ligand 1 (PD-L1), enabling tumor immune evasion. To address this issue, we developed innovative ROS-responsive cationic poly(ethylene imine) (PEI) nanogels using selenol chemistry-mediated multicomponent reaction (MCR) technology.

Multilevel Anti-counterfeiting Barcode with Enhanced Information Encryption Based on Stimulus-Responsive Digital Polymers.

In response to the escalating challenges of counterfeiting due to technological and socioeconomic advancements, a novel trilevel anti-counterfeiting Quick Response (QR) code system has been developed. This system integrates digital polymers with QR code and stimulus-responsive chromophores, , rhodamine B (RB), rhodamine 6G (R6G), and spiropyran (SP), to provide a sophisticated security solution. This advanced barcode remains concealed until specific stimuli reveal it and can be scanned by a smartphone, enabling first and second level anti-counterfeiting.

Ultra-Fast Selenol-Yne Click (SYC) Reaction Enables Poly(selenoacetal) Covalent Adaptable Network Formation.

The emergence of covalent adaptable networks (CANs) based on dynamic covalent bonds (DCBs) presents a promising avenue for achieving resource recovery and utilization. In this study, we discovered a dynamic covalent bond called selenacetal, which is obtained through a double click reaction between selenol and activated alkynes. Density functional theory (DFT) calculations demonstrated that the ΔG for the formation of selenoacetals ranges from 12 to 18 kJ mol, suggesting its potential for dynamic reversibility.

Photo-Deactivation Strategy for Switchable ATRP with the Assistance of Molecular Switches.

Light irradiation is an external stimulus, rapidly developed in switchable atom transfer radical polymerization (ATRP) via photo-activation methods in recent years. Herein, a photo-deactivation strategy is introduced to regulate ATRP with the assistance of photoswitchable hexaarylbiimidozole (HABI). Under visible light irradiation and in the presence of HABI, ATRP is greatly decelerated or quenched depending on the concentration of HABI.

Advanced Multifunctional Hydrogels for Enhanced Wound Healing through Ultra-Fast Selenol-SAr Chemistry.

Fabrication of versatile hydrogels in a facile and effective manner represents a pivotal challenge in the field of biomaterials. Herein, a novel strategy is presented for preparing on-demand degradable hydrogels with multilevel responsiveness. By employing selenol-dichlorotetrazine nucleophilic aromatic substitution (SAr) to synthesize hydrogels under mild conditions in a buffer solution, the necessity of additives or posttreatments can be obviated.

Heteroatom Substitution Strategy Modulates Thermodynamics Towards Chemically Recyclable Polyesters and Monomeric Unit Sequence by Temperature Switching.

In this paper, we proposed a heteroatom substitution strategy (HSS) in the δ-valerolactone (VL) system to modulate thermodynamics toward chemically recyclable polyesters. Three VL-based monomers containing different heteroatoms (M (N), M (S), and M (O)), instead of C-5 carbon, were designed and synthesized to verify our proposed HSS. All three monomers undergo organocatalytic living/controlled ROP and controllable depolymerization.

Tuning the Mechanical Properties of 3D-printed Objects by the RAFT Process: From Chain-Growth to Step-Growth.

Photoinduced 3D printing based on the reversible addition-fragmentation chain transfer (RAFT) process has emerged as a robust method for creating diverse functional materials. However, achieving precise control over the mechanical properties of these printed objects remains a critical challenge for practical application. Here, we demonstrated a RAFT step-growth polymerization of a bifunctional xanthate and bifunctional vinyl acetate.

Unraveling Dynamic Helicity Inversion and Chirality Transfer through the Synthesis of Discrete Azobenzene Oligomers by an Iterative Exponential Growth Strategy.

Unraveling the chirality transfer mechanism of polymer assemblies and controlling their handedness is beneficial for exploring the origin of hierarchical chirality and developing smart materials with desired chiroptical activities. However, polydisperse polymers often lead to an ambiguous or statistical evaluation of the structure-property relationship, and it remains unclear how the iterative number of repeating units function in the helicity inversion of polymer assemblies. Herein, we report the macroscopic helicity and dynamic manipulation of the chiroptical activity of supramolecular assemblies from discrete azobenzene-containing oligomers (azooligomers), together with the helicity inversion and morphological transition achieved solely by changing the iterative chain lengths.

Iodonium Initiators: Paving the Air-free Oxidation of Spiro-OMeTAD for Efficient and Stable Perovskite Solar Cells.

To date, perovskite solar cells (pero-SCs) with doped 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) hole transporting layers (HTLs) have shown the highest recorded power conversion efficiencies (PCEs). However, their commercialization is still impeded by poor device stability owing to the hygroscopic lithium bis(trifluoromethanesulfonyl)imide and volatile 4-tert-butylpyridine dopants as well as time-consuming oxidation in air. In this study, we explored a series of single-component iodonium initiators with strong oxidability and different electron delocalization properties to precisely manipulate the oxidation states of Spiro-OMeTAD without air assistance, and the oxidation mechanism was clearly understood.

Precision Sequence-Defined Polymers: From Sequencing to Biological Functions.

Precise sequence-defined polymers (SDPs) with uniform chain-to-chain structure including chain length, unit sequence, and end functionalities represent the pinnacle of sophistication in the realm of polymer science. For example, the absolute control over the unit sequence of SDPs allows for the bottom-up design of polymers with hierarchical microstructures and functions. Accompanied with the development of synthetic techniques towards precision SDPs, the decoding of SDP sequences and construction of advanced functions irreplaceable by other synthetic materials is of central importance.

Sequence effect on the self-assembly of discrete amphiphilic co-oligomers with fluorene-azobenzene semirigid backbones.

Sequences can have a dramatic impact on the unique properties and self-assembly in natural macromolecules, which has received increasing interest. Herein, we report a series of discrete amphiphilic co-oligomers with the same composition but different building blocks in a semirigid backbone. These sequence-defined oligomers possess two primary amine groups on the side chain of the azobenzene building block, and hence, they become amphipathic due to quaternization of the amine groups when protonated in acidic aqueous solution.

Enhancing Ultrasound-Assisted Iodine-Mediated Reversible-Deactivation Radical Polymerization by Piezoelectric Nanoparticles.

The development of mechanochemical tools for regulating the polymerization process has received an increasing amount of attention in recent years. Herein, we report the example of the mechanically controlled iodine-mediated reversible-deactivation radical polymerization (mechano-RDRP) using piezoelectric tetragonal BaTiO nanoparticles (T-BTO) as mechanoredox catalyst and alkyl iodide as the initiator. We demonstrated a more efficient mechanochemical initiation and reversible deactivation process than sonochemical activation via a mechanoredox-mediated alkyl iodide cleavage reaction.

Tailoring Polymerization Controllability and Dispersity Through a Photoswitchable Catalyst Strategy.

Modulating on-demand polymerization is a challenge in synthetic macromolecules. Herein, tailoring polymerization controllability and dispersity during single-electron transfer mediated living radical polymerization (SET-LRP) of methyl methacrylate (MMA) is achieved. Hexaarylbiimidazole (HABI) is employed as a photoswitchable catalyst, allowing reversible control of catalytic activity between an active and inactive state.

Selenide-linked polydopamine-reinforced hybrid hydrogels with on-demand degradation and light-triggered nanozyme release for diabetic wound healing.

Background: Multifunctional hydrogels with controllable degradation and drug release have attracted extensive attention in diabetic wound healing. This study focused on the acceleration of diabetic wound healing with selenide-linked polydopamine-reinforced hybrid hydrogels with on-demand degradation and light-triggered nanozyme release.

Methods: Herein, selenium-containing hybrid hydrogels, defined as DSeP@PB, were fabricated via the reinforcement of selenol-end capping polyethylene glycol (PEG) hydrogels by polydopamine nanoparticles (PDANPs) and Prussian blue nanozymes in a one-pot approach in the absence of any other chemical additive or organic solvent based on diselenide and selenide bonding-guided crosslinking, making them accessible for large-scale mass production.

Tailoring Hydrogen-Bonding Strategy for Sequence-Dependent and Thermo/pH Dual-Responsive Clusteroluminescence.

Rational design of monomer sequence for desired properties is challenging. This study investigates the effect of monomer distribution of double hydrophilic copolymers (DHCs) with electron-rich units on cluster triggered emission (CTE) capacity. By means of combining latent monomer strategy, reversible addition fragmentation chain transfer (RAFT) polymerization and selective hydrolysis technology, the random, pseudo di-block and the gradient DHCs consisting of pH-responsive polyacrylic acid (PAA) segments and thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) segments were successfully synthesized in a controlled manner.

Unexpected chirality transition and inversion mediated by dissolution-aggregation and the odd-even effect.

The evolution of hierarchical chirality at macromolecular and supramolecular levels in biological systems is ubiquitous; however, achieving precise control over transitions between them in polymer systems is still challenging. Here, we reported multiple chiroptical transitions and inversion phenomena in side-chain azobenzene (Azo) polymers, PAzo-l/d- ( = 3, 6, 7, 8, 9, and 10, where is the total number of atoms from the chiral stereocenter to the Azo unit), with different distances from the chiral stereocenter to the Azo unit. In the case of = 3, an unexpected macromolecular-to-supramolecular chirality transition and inversion occurred when the Azo-polymer underwent from a macromolecular-dissolved state to a supramolecular-aggregated state.

Digital micelles of encoded polymeric amphiphiles for direct sequence reading and ex vivo label-free quantification.

Identification and quantification of synthetic polymers in complex biological milieu are crucial for delivery, sensing and scaffolding functions, but conventional techniques based on imaging probe labellings only afford qualitative results. Here we report modular construction of precise sequence-defined amphiphilic polymers that self-assemble into digital micelles with contour lengths strictly regulated by oligourethane sequences. Direct sequence reading is accomplished with matrix-assisted laser desorption/ionization (MALDI) tandem mass spectrometry, facilitated by high-affinity binding of alkali metal ions with poly(ethylene glycol) dendrons and selective cleavage of benzyl-carbamate linkages.

Research Progress in Polypeptoids Prepared by Controlled Ring-Opening Polymerizations.

Polypeptoids, structural mimics of polypeptides, have attracted considerable attention due to their biocompatibility, proteolytic stability, thermal processability, good solubility, synthetic accessibility, and structural diversity. Polypeptoids have emerged as an interesting material in both polymer science and biological field. This review primarily discusses the research progress of polypeptoids prepared by controlled ring-opening polymerizations in the past decade, including synthetic strategies of monomers, polymerizations by different initiators, postfunctionalization, fundamental properties, crystallization-driven self-assembly, and potential biological applications.

Catalyst-Free, Visible-Light-Induced Step-Growth Polymerization by a Photo-RAFT Single-Unit Monomer Insertion Reaction.

Photoinduced polymerization is an attractive technique with the advantages of easy operation, mild conditions, and excellent temporospatial controllability. However, the application of this technique in step-growth polymerization is highly challenging. Here, we present a catalyst-free, visible-light-induced step-growth polymerization method utilizing a photo-RAFT single-unit monomer insertion reaction between the xanthate and vinyl ether groups.

Manganese-Catalyzed Batch and Continuous Flow Cationic RAFT Polymerization Induced by Visible Light.

We present a robust manganese-catalyzed cationic reversible addition-fragmentation chain transfer (RAFT) polymerization induced by visible light. Well-defined poly(vinyl ether)s with controlled molecular weight and molecular weight distributions (MWDs) can be conveniently prepared at room temperature without monomer purification. The commercially available manganese carbonyl bromide is used as the photocatalyst for cationic RAFT polymerization.