A linear supramolecular polymer based on the self‐assembly of an easily available copillar[5]arene monomer is efficiently prepared, which is evidenced by the NMR spectroscopy, viscosity measurement, and DOSY experiment. The single‐crystal X‐ray analysis reveals that the polymerization of the AB‐type monomer is driven by the quadruple CH•••π interactions and one CH•••O interaction.
Here, a novel method is demonstrated for the preparation of three‐arm branched microporous organic nanotube networks (TAB‐MONNs) based on molecular templating of three‐arm branched core–shell bottlebrush copolymers and Friedel–Crafts alkylation reaction. The unique three‐arm branched bottlebrush copolymers are synthesized by a combination of atom transfer radical polymerization, reversible addition‐fragmentation chain transfer polymerization, and ring‐opening polymerization techniques. In this approach, the length and diameter of branched tube units can be well‐controlled by rational molecular design. Moreover, the as‐prepared TAB‐MONNs possess a high surface area and exhibit a superior adsorption capacity for Rhodamine 6G (R6G) and p‐cresol.
A template‐free method is described to fabricate continuous‐phase, porous polymer films by simultaneous phase separation during vapor deposition polymerization. The technique involves concurrent polymerization, crosslinking, and phase separation of condensed species and reaction products. Deposited films form open‐cell, macroporous structures consisting of crosslinked and glassy poly(glycidyl methacrylate). By limiting phase separation during vapor phase deposition, spatially dependent morphologies, such as layered morphologies, can be grown. Results show that combining vapor deposition polymerization with phase separation establishes morphological control, which may be applied to applications including cellular scaffolds, thin cushions and vibration dampers, and membranes for separations.
A convenient synthesis of sustainable polyamides, which contain side groups and stereocenters, starting from the biobased small terpene β‐pinene is reported. The polyamides, which are obtained via the pinene‐based lactam via ring‐opening polymerization, show excellent thermal properties, rendering this approach very interesting for the utilization of novel biobased and structurally significant high‐performance polymers and materials. Polymer masses and yields are shown to be dependent on different parameters, and the stereoinformation of the lactam monomer can thus be transferred into the polymer chain. In addition, another lactam side product can also be transformed to polyamides.
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.
In the last decades, metallopolymers have received great attention due to their various applications in the fields of materials and chemistry. In this article, a neutral 18‐electron exo‐substituted η4‐cyclopentadiene CpCo(I) unit‐containing polymer is prepared in a controlled/“living” fashion by combining facile click chemistry and ring‐opening metathesis polymerization (ROMP). This Co(I)‐containing polymer is further used as a heterogeneous macromolecular catalyst for atom transfer radical polymerization (ATRP) of methyl methacrylate and styrene.
The modulation of the cloud point of aqueous poly(N,N‐diethylacrylamide) solutions via the formation of supramolecular cyclodextrin complexes with hydrophobic end groups, namely adamantyl, tert‐butyl phenyl and azobenzene, synthesized via RAFT polymerization is described. The dependence of the apparent cloud points after cyclodextrin complexation is investigated with respect to the type and quantity of the guest end group, the polymer chain length and the cyclodextrin/end group ratio. Furthermore, the effect is reversed via the addition of guest molecules or via biocompatible enzymatic degradation of the cyclodextrins entire.
Polyacrylamides containing pendant aminobisphosphonate groups are synthesized via reversible addition‐fragmentation chain transfer (RAFT) polymerization and a multicomponent postpolymerization functionalization reaction. A Moedritzer–Irani reaction installs the phosphonic acid groups on well‐defined, RAFT‐generated polymers bearing a pendant amine. An alternate route to the same materials is developed utilizing a three‐component Kabachnik–Fields reaction and subsequent dealkylation. Kinetics of the RAFT polymerization of the polymer precursor are studied. Successful functionalization is demonstrated by NMR and FTIR spectroscopy and elemental analysis of the final polymers.
Aggregation‐induced emission (AIE) dye‐based cross‐linked fluorescent polymeric nanoparticles (FPNs) are facilely prepared via a two‐step polymerization process including emulsion polymerization and subsequent anhydride cross‐linking. Then, a variety of characterization methods are carried out to determine the performance of the FPNs, which show high dispersibility and strong fluorescence in an aqueous solution due to the hydrophilic carboxyl groups on the surfaces and the AIE components as the cores. Biocompatibility evaluation and cell imaging results suggest that these FPNs are biocompatible for cell imaging. More importantly, this cross‐linking strategy is proven to overcome the issue of critical micelle concentration and opens the opportunity to develop more robust fluorescent bioprobes.
Herein, a novel photoinitiated polymerization‐induced self‐assembly formulation via photoinitiated reversible addition–fragmentation chain transfer dispersion polymerization of glycidyl methacrylate (PGMA) in ethanol–water at room temperature is reported. It is demonstrated that conducting polymerization‐induced self‐assembly (PISA) at low temperatures is crucial for obtaining colloidal stable PGMA‐based diblock copolymer nano‐objects. Good control is maintained during the photo‐PISA process with a high rate of polymerization. The polymerization can be switched between “ON” and “OFF” in response to visible light. A phase diagram is constructed by varying monomer concentration and degree of polymerization. The PGMA‐based diblock copolymer nano‐objects can be further cross‐linked by using a bifunctional primary amine reagent. Finally, silver nanoparticles are loaded within cross‐linked vesicles via in situ reduction, exhibiting good catalytic properties.
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 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.
Synthesis of a cyclodextrin (CD) polyrotaxane is achieved for the first time by simultaneous free radical polymerization of isoprene, threading by CD, and stoppering by copolymerization of styrene. This reaction is performed in an eco‐friendly manner in an aqueous medium similar to classical emulsion polymerization. Threaded CD rings of the polyrotaxane are cross‐linked by hexamethylene diisocyanate, leading to highly elastic slide‐ring gels.
Poly‐(N‐isopropylacrylamide) (PNIPA) hydrogel films doped with uniaxially aligned liquid crystalline (LC) nanosheets adsorbed with a dye are synthesized and its anomalous photothermal deformation is demonstrated. The alignment of the nanosheet LC at the cm‐scale is easily achieved by the application of an in‐plane or out‐of‐plane AC electric field during photo‐polymerization. A photoresponsive pattern is printable onto the gel with μm‐scale resolution by adsorption of the dye through a pattern‐holed silicone rubber. When the gel is irradiated with light, only the colored part is photothermally deformed. Interestingly, the photo‐irradiated gel shows temporal expansion along one direction followed by anisotropic shrinkage, which is an anomalous behavior for a conventional PNIPA gel.
An acceleration effect and selective monomer addition during RAFT copolymerization of the oppositely‐charged ionic monomers in dilute aqueous solution at 25 °C are reported. The reaction is conducted using a non‐ionic water‐soluble polymer as a macromolecular chain transfer agent under visible light irradiation. A fast iterative polymerization can be induced, even in dilute solution, by the favorable ionic interactions and in situ self‐assembly of zwitterionic growing chains. Selelctive monomer addition is achieved in the statistical copolymerization due to the ion‐pairing of the oppositely‐charged monomers, such as precisely the same reaction rates at a 1:1 of monomer ratio, otherwise a faster reaction of the minor monomer component over the major one. These behaviors open up an avenue towards the rapid synthesis of sequence‐controlled zwitterionic polyelectrolytes that can satisfy the demands of emerging biological applications.
Stimuli responsive surfaces that show reversible fluorescence switching behavior in response to temperature changes were fabricated. Oligo(ethylene glycol) methacrylate thermoresponsive polymers with amine end‐groups were prepared by atom transfer radical polymerization (ATRP). The polymers were patterned on silicon surfaces by electron beam (e‐beam) lithography, followed by conjugation of self‐quenching fluorophores. Fluorophore conjugated hydrogel thin films were bright when the gels were swollen; upon temperature‐induced collapse of the gels, self‐quenching of the fluorophores led to significant attenuation of fluorescence. Importantly, the fluorescence was regained when the temperature was cooled. The fluorescence switching behavior of the hydrogels for up to ten cycles was investigated and the swelling‐collapse was verified by atomic force microscopy. Morphing surfaces that change shape several times upon increase in temperature were obtained by patterning multiple stimuli responsive polymers.
Well‐defined ABC triblock copolymers based on two hydrophilic blocks, A and C, and a hydrophobic block B are synthesized and their self‐assembly behavior is investigated. Interestingly, at the same solvent, concentration, pH, and temperature, different shape micelles are observed, spherical and worm‐like micelles, depending on the preparation method. Specifically, spherical micelles are observed with bulk rehydration while both spherical and worm‐like micelles are observed with film rehydration.
Graphene oxide (GO) is effective in catalyzing a wide variety of organic reactions and a few types of polymerization reactions. No radical chain polymerizations catalyzed by GO have been reported. In this article, we probe the catalytic role and acceleration effect of GO for self‐initiated radical chain polymerizations of acrylic acid (AA) in the presence of GO and a pre‐existing polymer, poly(N‐vinylpyrrolidone) (PVP), from a calorimetric perspective. Gelation experiments and DSC studies show that GO can function as a catalyst to accelerate the radical chain polymerization of AA. Isothermal polymerization kinetic data shows that the addition of GO diminishes the induction periods and increases the polymerization rates, as indicated by the much enhanced overall kinetic rate constants and lowered activation energies. The catalytic effect of GO for the polymerization of AA is attributed to the acidity of GO and the hydrogen bonding interactions between GO and monomer molecules and/or polymers.
A novel water insoluble, multifunctional poly(ethylene glycol), poly(hydrazide ethylene glycol‐co‐benzyl glycidyl ether) (P(HZ‐co‐BnGE)), is synthesized via thiol‐ene click reaction of poly(allyl glycidyl ether‐co‐benzyl glycidyl ether) (P(AGE‐co‐BnGE)). The base polymer P(AGE‐co‐BnGE) is previously prepared by anionic ring‐opening copolymerization of the corresponding monomers. To demonstrate utility, bicompartmental microspheres and microcylinders containing P(HZ‐co‐BnGE) in one of the compartments are prepared via electrohydrodynamic (EHD) co‐jetting. Next, spatially controlled surface reactivity toward sugars is demonstrated by selective binding of 2α‐mannobiose to the P(HZ‐co‐BnGE) compartment only, as confirmed by a carbohydrate‐lectin‐binding assay. These sugar‐reactive hydrazide‐presenting microparticles have potential applications for glyco‐targeted drug delivery.
Imitating the natural “energy cascade” architecture, we present a single‐molecular rod‐like nano‐light harvester (NLH) based on a cylindrical polymer brush. Block copolymer side chains carrying (9,9‐diethylfluoren‐2‐yl)methyl methacrylate units as light absorbing antennae (energy donors) are tethered to a linear polymer backbone containing 9‐anthracenemethyl methacrylate units as emitting groups (energy acceptors). These NLHs exhibit very efficient energy absorption and transfer. Moreover, we manipulate the energy transfer by tuning the donor–acceptor distance.
