The formation of a poly(2,6‐carbazole) derivative during an electrochemical polymerization process is shown. Comparison of 3,5‐bis(9‐octyl‐9H‐carbazol‐2‐yl)pyridine and 3,5‐bis(9‐octyl‐9H‐carbazol‐3‐yl)pyridine by electrochemical and UV–Vis‐NIR spectroelectrochemical measurements and DFT (density functional theory) calculation prove the formation of a poly(2,6‐carbazole) derivative. Both of the compounds form stable and electroactive conjugated polymers.
A simple and effective airflow method to prepare sandwich‐type block copolymer films is reported. The films are composed of three layers: vertically oriented nanocylinders align in both upper and bottom layers and irregular nanocylinders exist in the bulk of the film. The vertically oriented nanocylinders in both sides can provide high accessibility to ions and ensures the exchange of chemical species between the membrane and external environment, while the irregularly oriented nanocylinders in the middle part of the film can prolong the pathway of ions transportation and enhance ions selectivity.
Metallocenes are organometallic compounds with reversible redox profiles and tunable oxidation and reduction potentials, depending on the metal and substituents at the cyclopentadienyl rings. Metallocenes have been introduced in macromolecules to combine the redox‐activity with polymer properties. There are many examples of such hydrophobic polymer materials, but much fewer water‐soluble examples are found scattered across the polymer literature. However, in terms of drug delivery and other biological applications, water solubility is essential. For this very reason, all the synthetic routes to water‐soluble metallocene containing polymers are collected and discussed here. The focus is on neutral ferrocene‐ and ruthenocene‐containing and charged cobaltocenium‐containing macromolecules (i.e., symmetrical sandwich complexes). The synthetic protocols, self‐assembly behavior, and other benefits of the obtained materials are discussed.
The controlled synthesis of poly(oligo(2‐ethyl‐2‐oxazoline)methacrylate) (P(OEtOxMA)) polymers by Cu(0)‐mediated polymerization in water/methanol mixtures is reported. Utilizing an acetal protected aldehyde initiator for the polymerization, well‐defined polymers are synthesized (>99% conversion, Ð < 1.25) with subsequent postpolymerization deprotection resulting in α‐aldehyde end group containing comb polymers. These P(OEtOxMA) are subsequently site‐specifically conjugated, via reductive amination, to a dipeptide (NH2‐Gly‐Tyr‐COOH) as a model peptide, prior to conjugation to the functional peptide oxytocin. The resulting oxytocin conjugates are evaluated in comparison to poly(oligo(ethylene glycol) methyl ether methacrylate) combs synthesized in the same manner for potential effects on thermal stability in comparison to the native peptide.
A novel and non‐cytotoxic self‐healing supramolecular elastomer (SE) is synthesized with small‐molecular biological acids by hydrogen‐bonding interactions. The synthesized SEs behave as rubber at room temperature without additional plasticizers or crosslinkers, which is attributed to the phase‐separated structure. The SE material exhibits outstanding self‐healing capability at room temperature and essential non‐cytotoxicity, which makes it a potential candidate for biomedical applications.
A series of fluorene‐based conjugated polymers containing the aggregation‐induced emissive (AIE)‐active tetraphenylethene and dicarboxylate pseudocrown as a receptor exhibits a unique dual‐mode sensing ability for selective detection of lead ion in water. Fluorescence turn‐off and turn‐on detections are realized in 80%–90% and 20% water in tetrahydrofuran (THF), respectively, for lead ion with a concentration as low as 10−8 m .
A triptycene‐based microporous organic polymer (MOP) in which 2,6‐bis(benzimidazol‐2‐yl)pyridine (bbp) is incorporated as linkage and coordination site is designed and synthesized. Pd(II) ions are further immobilized in this MOP through the coordination interactions between Pd(II) ion and nitrogen atoms of bbp. The resulting material shows high stability and exhibits excellent heterogeneously catalytic activity for the Suzuki–Miyaura cross‐coupling reaction. Its high efficiency can be maintained after being reused for a number of cycles.
New monolithic materials comprising zeolitic imidazolate framework (ZIF‐8) located on the pore surface of poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) monolith previously functionalized with N‐(3‐aminopropyl)‐imidazole have been prepared via a layer‐by‐layer self‐assembly strategy. These new ZIF‐8@monolith hybrids are used as solid‐phase carriers for enzyme immobilization. Their performance is demonstrated with immobilization of a model proteolytic enzyme trypsin. The best of the conjugates enable very efficient digestion of proteins that can be achieved in mere 43 s.
The structure of P3HT in P3HT:PCBM films is examined on a poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) substrate subjected to cryo‐cooling to low temperature (−143 °C) followed by gradual heating to 50 °C. The behavior of these systems is examined in the absence and presence of an Al electrode on top of the P3HT:PCBM film. At temperatures below −10 °C, only the type‐I phase of P3HT is observed. However, the type‐II phase of P3HT starts to form near −10 °C, in both the presence and absence of the Al layer. In the system without an Al layer, the type‐II phase disappears at 30 °C, but this phase persists to 50 °C in the presence of the Al layer. Concomitant with the formation of the type‐II phase, a 1:3 ordered P3HT type‐II (1/3,0,0) superlattice peak emerged. The type‐II domains tend to form near the Al electrode layer and show a higher degree of alignment than the type‐I crystals.
Temperature‐triggered switchable nanofibrous membranes are successfully fabricated from a mixture of cellulose acetate (CA) and poly(N‐isopropylacrylamide) (PNIPAM) by employing a single‐step direct electrospinning process. These hybrid CA‐PNIPAM membranes demonstrate the ability to switch between two wetting states viz. superhydrophilic to highly hydrophobic states upon increasing the temperature. At room temperature (23 °C) CA‐PNIPAM nanofibrous membranes exhibit superhydrophilicity, while at elevated temperature (40 °C) the membranes demonstrate hydrophobicity with a static water contact angle greater than 130°. Furthermore, the results here demonstrate that the degree of hydrophobicity of the membranes can be controlled by adjusting the ratio of PNIPAM in the CA‐PNIPAM mixture.
Sulfonated poly(ether ether ketone) (SPEEK) thin film performs reversible thermochromic property by developing the color to be yellowish at the temperature above 190 °C. The detailed analyses based on temperature‐dependent techniques suggest the thermal treatment inducing the shifting of the hydrogen bond network between the sulfonated group and the hydrated water molecules to the π–π stacking among aromatic rings in SPEEK chains. Although it is general that the polymer chain packing is unfavorable at high temperature, the present work shows a good example that when the polymer chains can form specific molecular interaction, such as π–π stacking, even in harsh thermal treatment, a rearrangement will effectively occur, which leads to an external stimuli‐responsive property.
Cross‐linked azobenzene liquid‐crystalline polymer films with a poly(oxyethylene) backbone are synthesized by photoinitiated cationic copolymerization. Azobenzene moieties in the film surface toward the light source are simultaneously photoaligned during photopolymerization with unpolarized 436 nm light and thus form a splayed alignment in the whole film. The prepared films show reversible photoinduced bending behavior with opposite bending directions when different surfaces of one film face to ultraviolet light irradiation.
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.
Developing simple methods to organize nanoscale building blocks into ordered superstructures is a crucial step toward the practical development of nanotechnology. Bottom‐up nanotechnology using self‐assembly bridges the molecular and macroscopic, and can provide unique material properties, different from the isotropic characteristics of common substances. In this study, a new class of supramolecular hydrogels comprising 40 nm thick linear polymer layers sandwiched between nanolayers of self‐assembled amphiphilic molecules are prepared and studied by nuclear magnetic resonance spectroscopy, scanning electronic microscopy, small angle X‐ray diffraction, and rheometry. The amphiphilic molecules spontaneously self‐assemble into bilayer membranes when they are in liquid‐crystal state. The hydrogen bonds at the interface of the nanolayers and linear polymers serve as junctions to stabilize the network. These hydrogels with layered structure are facile to prepare, mechanically stable, and with unique temperature‐dependent optical transparency, which makes it interesting in applications, such as soft biological membranes, drug release, and optical filters.
Dynamic covalent hydrogels are facilely prepared from biocompatible polysaccharides in physiological conditions by the formation of phenylboronate ester cross‐links. This is based on the simple mixing of carboxylate‐containing polysaccharides (i.e., hyaluronic acid or carboxymethylcellulose) modified with phenylboronic acid and maltose moieties according to mild coupling reactions performed in aqueous solution. The formation of dynamic networks based on reversible boronic‐ester cross‐links is demonstrated by analyzing their rheological behavior. This study shows that these gels can adapt their structure in response to chemical stimuli such as variations in pH or addition of glucose and self‐heal.
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.
Amino‐cellulose‐based nanofibers are prepared by electrospinning of blended solutions of 6‐deoxy‐6‐trisaminoethyl‐amino (TEAE) cellulose and polyvinyl alcohol (PVA). The TEAE cellulose with a degree of substitution of 0.67 is synthesized via a nucleophilic displacement reaction starting from cellulose‐p‐toluenesulfonic acid ester. Several solution characteristics such as polymer concentration, electrical conductivity, and surface tension as well as setup parameters are investigated to optimize the ability of nanofiber formation. These parameters are evaluated using the rheological studies of the solutions. The nanofibers obtained are characterized by scanning electron microscopy (SEM) and show a high antimicrobial activity against Staphylococcus aureus and Klebsiella pneumoniae.
The polymerization of ocimene has been first achieved by half‐sandwich rare‐earth metal dialkyl complexes in combination with activator and AliBu3. The regio‐ and stereoselectivity in the ocimene polymerization can be controlled by tuning the cyclopentadienyl ligand and the central metal of the complex. The chiral cyclopentadienyl‐ligated Sc complex 1 prepares syndiotactic cis‐1,4‐polyocimene (cis‐1,4‐selectivity up to 100%, rrrr = 100%), while the corresponding Lu, Y, and Dy complexes 2 – 4 and the achiral pentamethylcyclopentadienyl Sc, Lu, and Y complexes 5 – 7 afford isotactic trans‐1,2‐polyocimenes (trans‐1,2‐selectivity up to 100%, mm = 100%).
A key feature of any living system is the ability to sense and react to the environmental stimuli. The biochemical characterization of the underlying biological sensors combined with advances in polymer chemistry has enabled the development of stimulus‐sensitive biohybrid materials that translate most diverse chemical and biological input into a precise change in material properties. In this review article, we first describe synthesis strategies of how biological and chemical polymers can functionally be interconnected. We then provide a comprehensive overview of how the different properties of biological sensor molecules such as competitive target binding and allosteric modulation can be harnessed to develop responsive materials with applications in tissue engineering and drug delivery.
Development of self‐healing polymers with spontaneous self‐healing capability and good mechanical performance is highly desired and remains a great challenge. Here, mechanical robust and self‐healable supramolecular hydrogels have been fabricated by using poly(2‐dimethylaminoethyl methacrylate) brushes modified silica nanoparticles (SiO2@PDMAEMA) as multifunctional macrocrosslinkers in a poly(acrylic acid) (PAA) network structure. The SiO2 nanoparticles serve as noncovalent crosslinkers, dissipating energy, whereas the electrostatic interactions between cationic PDMAEMA and anionic PAA render the hydrogel self‐healing property. This process provides a simple and broadly applicable strategy to produce mechanical strong and self‐healable materials.
