The synthesis of tetracene‐ and pentacene‐annulated norbornadienes, formed through the Diels–Alder reaction of a dehydroacene with cyclopentadiene is reported. Ring‐opening metathesis polymerization (ROMP) leads to polymers that are investigated with respect to their physical, optical, and electronic properties by gel permeation chromatography (GPC), UV–vis spectroscopy, and cyclic voltammetry. The pentacene‐containing polymer P1 is successfully integrated into an organic field‐effect transistor (OFET); the tetracene‐containing polymer P2 is integrated into an organic light‐emitting diode (OLED).
Polysiloxane‐modified tetraphenylethene (PTPESi) is successfully synthesized by attaching tetraphenylethene (TPE) units onto methylvinyldiethoxylsiloxane and subsequent polycondensation. Introducing polysiloxane into TPE has minimal effect on the photophysical properties and aggregation‐induced emission behavior of TPE. The highest occupied and lowest unoccupied molecular orbital (HOMO and LUMO) energy levels of PTPESi are located mainly on the tetraphenylethene moieties. The fluorescence intensity and the half width of the emission peak of PTPESi before and after annealing at 120 °C for 12 h are nearly the same, indicating high thermal stability and morphological stability. In addition, use of PTPESi film as a sensor toward the vapor‐phase detection of explosives is also studied and it displays quite high fluorescence quenching efficiency and good reversibility.
Continuous conductive gold nanofibers are prepared via the “tubes by fiber templates” process. First, poly(l‐lactide) (PLLA)‐stabilized gold nanoparticles (AuNP) with over 60 wt% gold are synthesized and characterized, including gel permeation chromatography coupled with a diode array detector. Subsequent electrospinning of these AuNP with template PLLA results in composite nanofibers featuring a high gold content of 57 wt%. Highly homogeneous gold nanowires are obtained after chemical vapor deposition of 345 nm of poly(p‐xylylene) (PPX) onto the composite fibers followed by pyrolysis of the polymers at 1050 °C. The corresponding heat‐induced transition from continuous gold‐loaded polymer tubes to smooth gold nanofibers is studied by transmission electron microscopy and helium ion microscopy using both secondary electrons and Rutherford backscattered ions.
Using the third‐generation Grubbs catalyst, the living ring‐opening metathesis polymerization of ferrocene/cobalticenium copolymers is conducted with theoretical numbers of 25 monomer units for each block, and their redox and electrochemical properties allow using the Bard–Anson electrochemical method to determine the number of metallocenyl units in each block.
Inspired by the molecular mechanics of mussel adhesive formation, a novel water‐soluble fluorescent macromolecule (polydopamine–polyethyleneimine (PDA–PEI)) is prepared by one‐pot copolymerization of dopamine (DA) and PEI. In this method, DA is polymerized to form PDA, which is then coupled with PEI mainly through Michael addition. The fluorescence property of PDA–PEI is mainly attributed to the Michael addition of PEI on the 5,6‐dihydroxyindole (DHI) units of PDA, where PEI can form hydrogen bonds with oxidative products such as DHI and force the DHI units to twist out of plane, resulting in a decrease in the intra‐ and intermolecular coupling of PDA. In addition, the influence of various metal cations on the fluorescence of the PDA–PEI copolymer is investigated. This work may facilitate the development of new strategies for controlling the emission characteristics of PDA.
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.
Nine different perylene derivatives are prepared and their ability to initiate, when combined with an iodonium salt (and optionally N‐vinylcarbazole), a ring‐opening cationic photopolymerization of epoxides under very soft halogen lamp irradiation is investigated. One of them is particularly efficient under a red laser diode exposure at 635 nm and belongs now to the very few systems available at this wavelength. The photochemical mechanisms are studied by steady‐state photolysis, electron spin resonance spin trapping, fluorescence, cyclic voltammetry, and laser flash photolysis techniques.
Here, a novel multi‐stimuli‐responsive fluorescence probe is developed by incorporating spiropyran group into the coumarin‐substituted polydiacetylene (PDA) vesicles. The fluorescence of PDA can be turned on upon heating, and can be quenched upon exposure to UV light irradiation or pH stimuli owing to the fluorescene resonance energy transfer (FRET) between the red‐phase PDA and the open merocyanine (MC) form of spiropyran. Moreover, we have designed and experimentally realized a set of logic gate operations for the first time based on the fluorescence modulation of the designed system upon thermal, photo, and pH stimuli. This novel type of resettable logic gates augur well for practical applications in information storage, optical recording, and sensing in complicated microenvironments.
Stratified polymer brushes are fabricated using microcontact printing (μCP) of initiator integrated polydopamine (PDOPBr) on polymer brush surfaces and the following surface initiated atom transfer radical polymerization (SI‐ATRP). It is found that the surface energy, chemically active groups, and the antifouling ability of the polymer brushes affect transfer efficiency and adhesive stability of the polydopamine film. The stickiness of the PDOPBr pattern on polymer brush surfaces is stable enough to perform continuous μCP and SI‐ATRP to prepare stratified polymer brushes with a 3D topography, which have broad applications in cell and protein patterning, biosensors, and hybrid surfaces.
Self‐assembled peptide/protein nanofibers are valuable 1D building blocks for creating complex structures with designed properties and functions. It is reported that the self‐assembly of silk‐elastin‐like protein polymers into nanofibers or globular aggregates in aqueous solutions can be modulated by tuning the temperature of the protein solutions, the size of the silk blocks, and the charge of the elastin blocks. A core‐sheath model is proposed for nanofiber formation, with the silk blocks in the cores and the hydrated elastin blocks in the sheaths. The folding of the silk blocks into stable cores—affected by the size of the silk blocks and the charge of the elastin blocks—plays a critical role in the assembly of silk‐elastin nanofibers. Furthermore, enhanced hydrophobic interactions between the elastin blocks at elevated temperatures greatly influence the nanoscale features of silk‐elastin nanofibers.
The surface of polyacrylonitrile (PAN) film is treated with ethyleneamines (EDA) in a simple chemical vapor phase reaction. Successful introduction of amine functional groups on the cyano group of PAN backbone is verified by FT‐IR and NMR measurements. Further UV‐vis and photoluminescence analyses show a red shift of the emission peak after repeated EDA treatment, which might be attributed to the formation of imine conjugation from newly formed carbon‐nitrogen bonds on the PAN backbone. Further confocal laser scanning microscopy reveals that selective patterning of EDA on PAN films is possible via local polydimethylsiloxane masking. The results indicate that both chemical and optical patterning on PAN film can be realized via a single reaction and show the potential of this novel methodology in selective patterning.
A pH‐responsive core cross‐linked star (CCS) polymer containing poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) arms was used as an interfacial stabilizer for emulsions containing toluene (80 v%) and water (20 v%). In the pH range of 12.1‐9.3, ordinary water‐in‐oil emulsions were formed. Intermediate multiple emulsions of oil‐in‐water‐in‐oil and water‐in‐oil‐in‐water were formed at pH 8.6 and 7.5, respectively. Further lowering the pH resulted in the formation of gelled high internal phase emulsions of oil‐in‐water type in the pH range of 6.4‐0.6. The emulsion behavior was correlated with interfacial tension, conductivity and configuration of the CCS polymer at different pH.
Microdevices designed for practical environmental pollution monitoring need to detect specific pollutants such as dioxins. Bisphenol A (BPA) has been widely used as a monomer for the synthesis of polycarbonate and epoxy resins. However, the recent discovery of its high potential ability to disrupt human endocrine systems has made the development of smart systems and microdevices for its detection and removal necessary. Molecule‐responsive microsized hydrogels with β‐cycrodextrin (β‐CD) as ligands are prepared by photopolymerization using a fluorescence microscope. The molecule‐responsive micro‐hydrogels show ultra‐quick shrinkage in response to target BPA. Furthermore, the flow rate of a microchannel is autonomously regulated by the molecule‐responsive shrinking of their hydrogels as smart microvalves.
Gold nanoshell‐functionalized polymer multilayer tubes can be used as potent therapeutic agents for remote killing of cancer cells in a controlled manner due to the emerging pressure wave and tube fragments piercing the cell wall. The explosion is based on rapid evaporation of water inside the tubes caused by photothermal effects. The mechanism of explosion is presented in theory and experiment. The explosion of the tubes depends on the absorption coefficient and size of the gold nanoshells in the tubes, whereby the placement of the gold particles inside or outside of the tubes has no obvious effect on the explosive properties.
Described herein is a new printing method—direct writing of conducting polymers (CPs)—based on pipette‐tip localized continuous electrochemical growth. A single barrel micropipette containing a metal wire (Pt) is filled with a mixture of monomer, supporting electrolyte, and an appropriate solvent. A droplet at the tip of the pipette contacts the substrate, which becomes the working electrode of a micro‐electrochemical cell confined to the tip droplet and the pipette. The metallic wire in the pipette acts as both counter and reference electrode. Electropolymerization forms the CP on the working electrode in a pattern controlled by the movement of the pipette. In this study, various width poly(pyrrole) 2D and 3D structures are extruded and characterized in terms of microcyclic voltammetry, Raman spectroscopy, and scanning electron microscopy.
A novel strategy for the incorporation of carbon dioxide into polymers is introduced. For this purpose, the Ugi five‐component condensation (Ugi‐5CC) of an alcohol, CO2, an amine, an aldehyde, and an isocyanide is used to obtain step‐growth monomers. Polymerization via thiol‐ene reaction or polycondensation with diphenyl carbonate gives diversely substituted polyurethanes or alternating polyurethane‐polycarbonates, respectively. Furthermore, the application of 1,12‐diaminododecane and 1,6‐diisocyanohexane as bifunctional components in the Ugi‐5CC directly results in the corresponding polyamide bearing methyl carbamate side chains ( = 19 850 g mol−1). The latter polymer is further converted into the corresponding polyhydantoin in a highly straightforward fashion.
A novel polymer featuring oligoaniline pendants that exhibits reversible electroactivity and good electrochromic properties with high contrast value, acceptable switching times, and excellent coloration efficiency is presented. This polymer can undergo reversible changes in fluorescence in response to reductive and oxidative chemical stimulus, pH, and electrical potential. The fluorescence switching operation shows reasonable reversibility and reproducibility when subjected to multiple stimuli. In this elegant fluorescence switching system, the oligoaniline pendants are used as fluorophore and regulatory units simultaneously.
An alkyne‐functionalized ruthenium(II) bis‐terpyridine complex is directly copolymerized with phenylacetylene by alkyne polymerization. The polymer is characterized by size‐exclusion chromatography (SEC), 1H NMR spectroscopy, cyclic voltammetry (CV) measurements, and thermal analysis. The photophysical properties of the polymer are studied by UV–vis absorption spectroscopy. In addition, spectro‐electrochemical measurements are carried out. Time‐resolved luminescence lifetime decay curves show an enhanced lifetime of the metal complex attached to the conjugated polymer backbone compared with the Ru(tpy)22+ model complex.
Via electron paramagnetic resonance (EPR) spectroscopy, the type of radicals occurring during acrylamide (AAm) homopolymerization in aqueous solution is investigated between −5 and +100 °C. The radicals are produced photochemically under stationary conditions. Midchain AAm radicals (MCRs) are clearly identified by EPR which demonstrates that secondary propagating AAm radicals (SPRs) undergo backbiting reactions. Above 50 °C, the fraction of MCRs even exceeds the one of SPRs. The extent of backbiting is however well below the one in butyl acrylate polymerization at identical temperature.
A group of crosslinked cyclic siloxane (Si O) and silazane (Si N) polymers are synthesized via solvent‐free initiated chemical vapor deposition (iCVD). Notably, this is the first report of cyclic polysilazanes synthesized via the gas‐phase iCVD method. The deposited nanoscale thin films are thermally stable and chemically inert. By iCVD, they can uniformly and conformally cover nonplanar surfaces having complex geometry. Although polysiloxanes are traditionally utilized as dielectric materials and insulators, our research shows these cyclic organosilicon polymers can conduct lithium ions (Li+) at room temperature. The conformal coating and the room temperature ionic conductivity make these cyclic organosilicon polymers attractive for use as thin‐film electrolytes in solid‐state batteries. Also, their synthesis process and properties have been systemically studied and discussed.
