By anchoring alkynylplatinum(II) terpyridine molecular tweezer/pyrene recognition motif on the chain‐ends of telechelic polycaprolactone, high‐molecular‐weight supramolecular polymers have been successfully constructed via noncovalent chain extension, which demonstrate fascinating rheological and thermal properties. Moreover, the resulting assemblies exhibit interesting temperature‐ and solvent‐responsive behaviors, which are promising for the development of adaptive functional materials.
The chemical control of cell division has attracted much attention in the areas of single cell‐based biology and high‐throughput screening platforms. A mussel‐inspired cytocompatible encapsulation method for achieving a “cell‐division control” with cross‐linked layer‐by‐layer (LbL) shells is developed. Catechol‐grafted polyethyleneimine and hyaluronic acid are chosen as polyelectrolytes for the LbL process, and the cross‐linking of polyelectrolytes is performed at pH 8.5. Cell division is controlled by the number of the LbL nanolayers and cross‐linking reaction. We also suggest a new measuring unit, , for quantifying “cell‐division timing” based on microbial growth kinetics.
In this work, the synthesis of various halogenated thiophenol derivatives is presented. These thiophenols are used as monomers in light‐initiated SRN1‐type radical polymerization reactions. The method provides easy access to industrially relevant poly(paraphenylene sulfide) and poly(metaphenylene sulfide). The influence of the halide leaving group and of other substituents in the thiophenol monomer on the polymerization process is investigated.
Today's olefin metathesis catalysts show high reactivity, selectivity, and functional group tolerance and allow the design of new syntheses of precisely functionalized polymers. Here the synthesis of a new end‐capping reagent is investigated allowing the introduction of a highly reactive activated ester end‐group at the polymer chain end as well as its prefunctionalization to directly introduce functional moieties. The versatility of this new end‐capping reagent is demonstrated by utilizing it to synthesize a so‐called termimer (a monomer with termination capabilities). Copolymerization of a norbornene derivative with the termimer leads to hyperbranched ring‐opening metathesis polymerization polymers as proven by gel permeation chromatography and MALDI‐ToF‐(matrix‐assisted laser desorption/ionization time of flight) mass spectrometry.
The controlled folding of a single polymer chain is for the first time realized by metal‐ complexation. α,ω‐Bromine functional linear polymers are prepared via activators regenerated by electron transfer (ARGET) ATRP (,SEC = 5900 g mol−1, Đ = 1.07 and 12 000 g mol−1, Đ = 1.06) and the end groups of the polymers are subsequently converted to azide functionalities. A copper‐catalyzed azide–alkyne cycloaddition (CuAAC) reaction is carried out in the presence of a novel triphenylphosphine ligand and the polymers to afford homotelechelic bis‐triphenylphosphine polymeric‐macroligands (MLs) (,SEC = 6600 g mol−1, Đ = 1.07, and 12 800 g mol−1, Đ = 1.06). Single‐chain metal complexes (SCMCs) are formed in the presence of Pd(II) ions in highly diluted solution at ambient temperature. The results derived via 1H and 31P{1H} NMR experiments, SEC, and DLS unambiguously evidence the efficient formation of SCMCs via metal ligand complexation.
A simple and versatile method is developed for preparing anisotropic polymer particles by pressing polymer microspheres at elevated temperatures. Polystyrene (PS) microspheres are used to demonstrate this approach. Depending on the mechanical deformation and wetting of the polymers on the substrates, polymer structures with special shapes such as barrel‐like or dumbbell‐like shapes can be prepared. The morphology of polymer structures can be controlled by the experimental parameters such as the pressing pressure, the pressing temperature, and the pressing time. The wetting of the polymers on the substrates dominates when the samples are annealing at higher temperatures for longer times.
A unique fabrication process of low molar mass, crystalline polypeptoid fibers is described. Thermoresponsive fiber mats are prepared by electrospinning a homogeneous blend of semicrystalline poly(N‐(n‐propyl) glycine) (PPGly; 4.1 kDa) with high molar mass poly(ethylene oxide) (PEO). Annealing of these fibers at ≈100 °C selectively removes the PEO and produces stable crystalline fiber mats of pure PPGly, which are insoluble in aqueous solution but can be redissolved in methanol or ethanol. The formation of water‐stable polypeptoid fiber mats is an important step toward their utilization in biomedical applications such as tissue engineering or wound dressing.
Hierarchical semicrystalline block copolymer nanoparticles are produced in a segmented gas‐liquid microfluidic reactor with top‐down control of multiscale structural features, including nanoparticle morphologies, sizes, and internal crystallinities. Control of multiscale structure on disparate length scales by a single control variable (flow rate) enables tailoring of drug delivery nanoparticle function including release rates.
Sodium alginate (SA), acting as a trypsin inhibitor by means of electrostatic interaction, is studied. The half‐maximal inhibitory concentration (IC50 = 0.05 μg mL−1) of this natural anionic polymer is about 400 times lower than that of commercial soybean trypsin inhibitor (STI). Unlike the Ca2+‐deprivation mechanisms, its inhibition may be attributed to preventing the trypsin active site (TAS) from accessing the macromolecular substrates instead of denaturing it. SA is an efficient, innocuous, and cost‐effective inhibitory excipient that can be conveniently used in many peptide and protein dosage formulations.
Polymer‐based crosslinked networks with intrinsic self‐repairing ability have emerged due to their built‐in ability to repair physical damages. Here, novel dual sulfide–disulfide crosslinked networks (s‐ssPxNs) are reported exhibiting rapid and room temperature self‐healability within seconds to minutes, with no extra healing agents and no change under any environmental conditions. The method to synthesize these self‐healable networks utilizes a combination of well‐known crosslinking chemistry: photoinduced thiol‐ene click‐type radical addition, generating lightly sulfide‐crosslinked polysulfide‐based networks with excess thiols, and their oxidation, creating dynamic disulfide crosslinkages to yield the dual s‐ssPxNs. The resulting s‐ssPxN networks show rapid self‐healing within 30 s to 30 min at room temperature, as well as self‐healing elasticity with reversible viscoelastic properties. These results, combined with tunable self‐healing kinetics, demonstrate the versatility of the method as a new means to synthesize smart multifunctional polymeric materials.
Herein a facile method is reported to prepare polymer gels based on the formation of acylhydrazone bond under mild conditions. A pillar[5]arene derivative appended with ten hydrazide groups provides multiple sites for the reaction with the aldehyde groups of bis(p‐formylphenyl) sebacate in the presence of a small amount of HCl as the catalyst in dimethyl sulfoxide (DMSO), producing transparent polymer organogels. The mechanical properties of gels can be easily tuned by the molar ratio of the reactant compounds. After solvent exchange from DMSO to water, translucent polymer hydrogels with dramatically enhanced strength and stiffness are obtained. The tensile breaking stress and Young's modulus of hydrogels are 20−60 and 1.2–2.7 MPa, respectively, 100 and 20 times those of the corresponding organogels. These robust hydrogels with ultrahigh stiffness should find applications such as in load‐bearing artificial organs. This work should merit designing functional materials using other macrocycles.
Atom transfer radical polymerization (ATRP) catalyzed by high oxidation state metal salts of FeX3 is developed for the first time in the absence of both external initiator and reducing agent. Methyl methacrylate (MMA) and styrene are polymerized successfully using FeX3/Phosphorous ligands with well‐controlled molecular weight distributions (=1.5). The molecular weight of the polymers increases with monomer consumption with the progress of time and the polymerization behaviors show a decent ATRP trend. Activators and initiators are suggested to generate in situ by the addition reaction of MMA and one equivalent of FeX3. The PMMA synthesized from without‐initiator system is characterized by 1H, 13C and DEPT (distortionless enhancement by polarization transfer nuclear magnetic resonance) nuclear magnetic resonance spectroscopy. Chain extension and copolymerization experiments prove the livingness of the obtained polymer.
The preparation of multifunctional polymers and block copolymers by a straightforward one‐pot reaction process that combines enzymatic transacylation with light‐controlled polymerization is described. Functional methacrylate monomers are synthesized by enzymatic transacylation and used in situ for light‐controlled polymerization, leading to multifunctional methacrylate‐based polymers with well‐defined microstructure.
Pillararene‐containing thermoresponsive polymers are synthesized via reversible addition–fragmentation chain transfer polymerization using pillararene derivatives as the effective chain transfer agents for the first time. These polymers can self‐assemble into micelles and form vesicles after guest molecules are added. Furthermore, such functional polymers can be further applied to prepare hybrid gold nanoparticles, which integrate the thermoresponsivity of polymers and molecular recognition of pillararenes.
Free radical terpolymerization of (N,N)‐dimethylacrylamide, ethylene‐glycol‐dimethacrylate and N‐(p‐ or m‐ethyl‐phenyl)acrylamide leads to para‐ and meta‐ethyl‐phenyl‐modified hydrophilic polymer networks. Polymeric networks of different molar ratios are prepared in special molds to give water swellable disc‐ shaped samples. The swelling behavior in water and aqueous cyclodextrin (CD) solution of the obtained samples is described while a distinctive differentiation between the para‐ and meta‐ethyl‐phenyl containing networks in CD solution can be found.
In this study, a new type of functional, self‐assembled nanostructure formed from porphyrins and polyamidoamine dendrimers based on hydrogen bonding in an aqueous solution is presented. As the aggregates formed are promising candidates for solar‐energy conversion, their photocatalytic activity is tested using the model reaction of methyl viologen reduction. The self‐assembled structures show significantly increased activity as compared to unassociated porphyrins. Details of interaction forces driving the supramolecular structure formation and regulating catalytic efficiency are fundamentally discussed.
The developments in membranes based on tailored block copolymers are reported with an emphasis on isoporous membranes. These membranes can be prepared in different geometries, namely flat sheets and hollow fibers. They display narrow pore size distributions due to their formation by self‐assembly. The preparation of these membranes and possibilities to further functionalize such membranes will be discussed. Different ways to control the pore size will be addressed, and the potential of block copolymer blends to fabricate membranes with tailored pore sizes will be shown.
The attempts to mediate iterative RAFT polymerization of ionic monomers through visible light irradiation in water at 20 °C is reported, in which complete conversions are attained in several tens of minutes and the propagation suspends/restarts immediately for multiple times on cycling irradiation. This technique suits the one‐pot synthesis of NH2/imidazole‐based polymers with tuned structures from homo to random, block, random‐block, and block‐random‐block, thus is robust and promising to control the sequence of the ionized water‐soluble reactive copolymers.
The application of cyclodextrin (CD)‐based host–guest interactions towards the fabrication of functional supramolecular assemblies and hydrogels is of particular interest in the field of biomedicine. However, as of late they have found new applications as advanced functional materials (e.g., actuators and self‐healing materials), which have renewed interest across a wide range of fields. Advanced supramolecular materials synthesized using this noncovalent interaction, exhibit specificity and reversibility, which can be used to impart reversible cross‐linking, specific binding sites, and functionality. In this review, various functional CD‐based supramolecular assemblies and hydrogels will be outlined with the focus on recent advances. In addition, an outlook will be provided on the direction of this rapidly developing field.
Though great attention has been paid in constructing well‐defined nano‐structures via the self‐assembly of amphiphilic macromolecules, the self‐assembly of non‐amphiphilic macromolecules in nanodroplet has drawn less attention up to now. Recently, we prepared a temperature‐responsive PEG‐based branched polymer with disulfide bonds in its backbone via reversible addition–fragmentation chain transfer (RAFT) polymerization of 2‐(2‐methoxyethoxy) ethyl methacrylate, oligo(ethylene glycol) methacrylate, and N,N′‐cystamine bisacrylamide. Subsequently, we loaded the branched polymer into nanodroplets, and have found that the self‐assembly behaviors of this branched polymer in the nanodroplet are different from those in common solution. Bioreducible nanocapsules with tunable size can easily formed in nanodroplet even at high concentration.
