Because of the complexity of monomer sequence formation during polymerization, it is necessary to employ programmed synthesis to prepare copolymers with well‐defined sequences. We introduce a computational tool that can generate recipes to synthesize copolymers with pre‐designed monomer sequences. An efficient design strategy was crafted based on analyzing the impact of varying multiple synthesis factors in forced gradient copolymerization on the targeted properties. Finally, the proposed design tool was applied to generate recipes for several different structural gradient copolymers as case studies. It was shown that a recipe that meets certain targets can be designed in minutes. The recipes that are designed can also be tailored according to different application requirements.
The importance of taking into account the principle of microscopic reversibility in the analysis of complex copolymerization systems is demonstrated. The analysis of a reversible copolymerization system in which segmental exchange is possible from the point of view of the reaction microreversibility proves that hetero‐reshuffling rate constants depend on homo‐reshuffling rate constants and copolymerization thermodynamics.
Organic π‐conjugated polymers have emerged as one of the most fascinating classes of materials as they have found utility in a host of plastic electronics technologies. The distance between π‐systems and their relative orientation dictate energy/charge transfer, conductivity, and photophysical properties of these materials in bulk. This Feature Article discusses π‐conjugated polymers and model compounds in which specific inter‐π‐system interactions are covalently enforced and the effect that the scaffolding has on optoelectronic properties.
We report syntheses of phenylene‐, biphenylene‐, and terphenylene‐layered polymers with a xanthene scaffold by the modified Suzuki‐Miyaura coupling reaction. Their optical properties were studied in detail. The polymer end‐capped by nitrobenzene units, which act as fluorescence quenchers, exhibited the photo‐excited energy transfer from the layered oligophenylenes to the terminal units.
In light of the increasing demand for ultra rapid and mild conjugation chemistries for use in macromolecular chemistry, the present Feature Article provides a critical overview of the very latest developments in this field. The principal aim, therefore, is the provision of a quick selection guide to aid in the formulation of a design strategy for novel functional materials and to provide recommendations for future developments in the chemistries discussed.
The use of decatungstate in combination with silanes to generate silyl radicals under green fluorescence bulb irradiation as well as sunlight exposure is described. The mechanisms are investigated by ESR and laser flash photolysis experiments. The high potential of this reaction is evidenced here when using a decatungstate/silane/diphenyl iodonium salt combination as an initiating system for the ring opening photopolymerization of epoxides.
The coating of super‐paramagnetic iron oxide nanoparticles (SPIONs) with multiple shells is demonstrated by building a layer assembled from carboxymethyldextran and poly(diallydimethylammonium chloride). Three shells are produced stepwise around aggregates of SPIONs by the formation of a polyelectrolyte complex. A growing particle size from 96 to 327 nm and a zeta potential in the range of +39 to ?51 mV are measured. Microscopic techniques such as TEM, SEM, and AFM exemplify the core‐shell structures. Magnetic force microscopy and vibrating sample magnetometer measurements confirm the architecture of the multishell particles. Cell culture experiments show that even nanoparticles with three shells are still taken up by cells.
Summary: A series of novel mesogen‐jacketed liquid crystal miktoarm star rod‐coil block copolymers were synthesized via atom transfer radical polymerization (ATRP). Their architectures {coil conformation of styrene segment and rigid rod conformation of {2,5‐bis[(4‐methoxyphenyl)oxycarbonyl]styrene} (MPCS) segment} were confirmed by GPC, 1H NMR, and MALDI‐TOF studies. The liquid crystalline behaviors of the synthesized copolymers are evidenced from POM observation. The liquid crystalline phase depends on the molecular weights of the rigid rod arm of miktoarm star copolymers.
An ultra‐fast fabrication of large‐scale colloidal PCs via spray coating was demonstrated. The latex spheres with hydrophobic core and hydrophilic shell were designed, and the latex shell with abundant COOH groups resulted in strong hydrogen bonding interaction among latex spheres, which boosted latex arrangement during the spray procedure. The resultant samples with area of 7 × 12 cm2 were easily fabricated within 1 min on different substrates. This ultra‐fast fabrication procedure would be of great importance for the practical application of PCs for optic devices and functional coatings.
CuII compounds coordinated octahedrally with nitriles and associated with bulky, non‐coordinating counter ions can be applied in the polymerization of isobutene at 30 °C. High yields and a high content of terminal double bonds are reached in the resulting highly reactive polyisobutylenes, while the molecular masses are moderate. Two of the coordinating nitriles are more weakly coordinated than the other four, as can be concluded from an exemplary X‐ray structure and from vibrational spectra, thus providing easily accessible sites for substrate coordination.
The coherent dynamic structure factor of a single polymer chain is calculated based on the model of a Rouse polymer chain constrained (confined) by a harmonic radial potential and its behavior in different limiting cases is analyzed. The strength of confinement is characterized using an effective diameter of the harmonic radial potential as a model parameter. The method provides a reliable model to study the crossover between unconstrained (Rouse) and constrained dynamics.
Near‐infrared (NIR) polymer light‐emitting diodes (PLEDs) based on a fluorene–dioctyloxyphenylene wide‐gap host material copolymerized with a low‐gap emitter are presented. Various loadings (1, 2.5, 10, 20 mol%) of the low‐gap emitter are studied, with higher loadings leading to decreased efficiencies likely due to aggregation effects. While the 10 mol% loading resulted in almost pure NIR emission (>99.6%), the 1 mol% loading yielded optimum device performance, which is among the best reported to date for a unblended single‐layer pure polymer emitter, with an external quantum efficiencies of 0.04% emitting at 909 nm. The high spectral purity of the PLEDs combined with their performance support the methodology of copolymerization as an effective strategy for developing NIR PLEDs.
The functionalization of magnetite (Fe3O4) nanoparticles with dopamine‐derived clickable biomimetic anchors is reported. Herein, an alkyne‐modified catechol‐derivative is employed as the anchor, as i) the catechol‐functional anchor groups possess irreversible covalent binding affinity to Fe3O4 nanoparticles, and ii) the alkyne terminus enables further functionalization of the nanoparticles by the grafting‐onto approach with various possibilities offered by ‘click’ chemistry. In the present work, azido‐end group functionalized Rhodamine and poly(ethylene glycol) (PEG) are utilized to coat the iron oxide nanoparticles to make them fluorescent and water soluble.
Biotinylated polymers with side‐chain aldehydes were prepared for use as multifunctional scaffolds. Two different biotin‐containing chain transfer agents (CTAs) and an aldehyde‐containing monomer, 6‐oxohexyl acrylate (6OHA), are synthesized. Poly(ethylene glycol) methyl ether acrylate (PEGA) and 6OHA are copolymerized by reversible addition‐fragmentation chain transfer (RAFT) polymerization in the presence of the biotinylated CTAs. The resulting polymers are analyzed by GPC and1H NMR spectroscopy. The polymer end groups contained a disulfide bond, which could be readily reduced in solution to remove the biotin. Reactivity of the aldehyde side chains is demonstrated by oxime and hydrazone formation at the polymer side chains, and conjugate formation of fluorescently labeled polymers with streptavidin is investigated by gel electrophoresis.
Polymer‐encapsulated silver nanoparticles were synthesized and sterically stabilized by a new core‐shell type system consisting of poly(S‐alt‐MA)‐graft‐PMMA copolymer that acts as a scaffold for the synthesis of size confined nanoparticles. The graft copolymer is synthesized via ambient temperature ATRP using the CuBr/PMDETA catalytic system at ambient temperature. The graft copolymer is hypothesized to function as a scaffold with the anhydride part interacting strongly with the silver ions, while the PMMA graft functions as a polymer brush that stabilizes the dispersion and prevents the particle aggregation due to a ‘polymer brush effect’. UV absorption and TEM studies confirm that the synthesized silver composite particles have a core‐shell structure.
