Facile Preparation of Tough, Puncture-Resistant Antibacterial Polyrotaxane Hydrogel.

Slide-ring hydrogels containing polyrotaxane structures have been widely developed, but current methods are more complex, in which modified cyclodextrins, capped polyrotaxanes, and multistep reactions are often needed. Here, a simple one-pot method dissolving the pseudopolyrotaxane (pPRX) in a mixture of acrylamide and boric acid to form a slide-ring hydrogel by UV light is used to construct a tough, puncture-resistant antibacterial polyrotaxane hydrogel. As a new dynamic ring cross-linking agent, boric acid effectively improves the mechanical properties of the hydrogel and involves the hydrogel with fracture toughness. The polyrotaxane hydrogel can withstand 1 MPa compression stress and maintain the morphology integrity, showing 197.5 mJ puncture energy under a sharp steel needle puncture. Meanwhile, its significant antibacterial properties endow the hydrogel with potential applications in the biomedical field.

Polyacetylene-Based Asymmetric Bicyclic Polymer by Blocking-Cyclization Technique.

A rare asymmetric bicyclic polymer containing different length of conjugated polyacetylene segments is synthesized by metathesis cyclopolymerization-mediated blocking-cyclization technique. The size of each single ring differs from each other, and the unique cyclic polymer topology is controlled by adjusting the feed ratio of monofunctional monomer to catalyst. The topological difference between linear and bicyclic polymers is confirmed by several techniques, and the visualized morphology of asymmetric bicyclic polymer is directly observed without tedious post-modification process. The photoelectric and thermal properties of polymers are investigated. This work expands the pathway for the derivation of cyclic polymers, and such unique topological structure enriches the diversity of cyclic polymer classes.

Synthesis of conjugated segment-based cyclic polymers for direct imaging of the cyclic molecular topology.

Conjugated polyacetylene-based monocyclic and bicyclic polymers were synthesized by blocking-cyclization metathesis polymerization using short ladderphanes as the initial motif and multi-cyclizing unit, and fully characterized to elucidate the cyclic characteristics and good photoelectric properties. Importantly, the molecular topology of rationally designed cyclic polymers was directly observed without a tedious post-modification treatment.

Pillararene-containing polymers with tunable fluorescence properties based on host-guest interactions.

Linear polymers containing pillar[5]arenes as the pendant groups were designed and synthesized via a ring-opening metathesis polymerization. Such polymers could form supramolecular brush polymers and exhibited tunable fluorescence properties based on the host-guest interactions.

A Stretchable Pillararene-Containing Supramolecular Polymeric Material with Self-Healing Property.

Constructing polymeric materials with stretchable and self-healing properties arise increasing interest in the field of tissue engineering, wearable electronics and soft actuators. Herein, a new type of supramolecular cross-linker was constructed through host-guest interaction between pillar[5]arene functionalized acrylate and pyridinium functionalized acrylate, which could form supramolecular polymeric material via photo-polymerization of n-butyl acrylate (BA). Such material exhibited excellent tensile properties, with maximum tensile strength of 3.4 MPa and strain of 3000%, respectively. Moreover, this material can effectively dissipate energy with the energy absorption efficiency of 93%, which could be applied in the field of energy absorbing materials. In addition, the material showed self-healing property after cut and responded to competitive guest.

Pillararene-Containing Polymers with Tunable Conductivity Based on Host-Guest Complexations.

Regulating the conductivity of conducting polymers has spurred increasing studies, aiming at meeting different demands in various fields, including chemosensors, photovoltaic cells, and so on. Herein, linear pillar[5]arene-containing conjugated polymers were designed and synthesized via metathesis cyclopolymerization of pillar[5]arene-functionalized 1,6-heptadiyne. Upon addition of an ionic guest, such polymers could form inclusion complexes, of which the glass transition temperature decreased dramatically. With the aid of ionic guest and host-guest complexations between the pendant pillararenes and guest, these supramolecular materials exhibited tunable conductivity from 10-12 to 10-3 S·cm-1 at 30 °C. In addition, compared with the polymers without pendant pillar[5]arenes, such polymers showed better compatibility with the ionic guest, which could prevent the leakage of the latter one and was good for the conductivity of the material.

Blocking-cyclization technique for precise synthesis of cyclic polymers with regulated topology.

Ring-closure and ring-expansion techniques are the two routes for extensive synthesis of cyclic polymers. Here, we report an alternative blocking-cyclization technique referred to as the third route to prepare cyclic polymers with regulated ring size and ring number by ring-opening metathesis polymerization of di- and monofunctional monomers in a one-pot process, where the polymer intermediates bearing two single-stranded blocks are efficiently cyclized by the cyclizing unit of propagated ladderphane to generate corresponding mono-, bis-, and tricyclic polymers, and the well-defined ladderphane structure plays a crucial role in forming the cyclic topology. Monocyclic polymer is further modified via Alder-ene reaction and the cyclic molecular topology is clearly demonstrated. The diversity features of cyclic polymers are comprehensively revealed. This strategy has broken through the limitations of previous two cyclizing routes, and indeed opens a facile and popular way to various cyclic polymers by commercial Grubbs catalyst and conventional metathesis polymerization.

Photoregulating of Stretchability and Toughness of a Self-Healable Polymer Hydrogel.

Supramolecular hydrogels that are assembled through dynamic host-guest interactions have presented apparent potential in the construction of materials with promising performance. Herein, a photoregulated hydrogel cross-linked by host-guest interactions with multifunctions of high stretchability, strong toughness, and rapid self-healing property is reported. The hydrogel exhibits unique light-responsive property due to the introduction of two photoisomerized groups. For example, the stress-strain curve of the original hydrogel indicates 1020% rupture strain with the maximum tensile strain value of 214 kPa. Upon 365 nm light irradiation for an hour, its tensile strain increases to 15 times with lower tensile stress indicating a better stretchability. Moreover, the hydrogel is photochromic and surface patternable, where it can reversibly switch color between luminous yellow and brown while exposed to 365 and 440 nm light irradiation. It holds great promise for applying in self-recovering optically controlled and labeled elastic mechanical materials.

Responsiveness and Morphology Study of Dual Stimuli-Controlled Supramolecular Polymer.

The synthesis and characterization of a linear supramolecular polymer formed by dual host-guest recognitions is presented. The polymer linked by the orthogonal interactions of azobenzene with ß-cyclodextrin and methyl viologen with sulfonatocalix[4]arene is constructed, and the morphology change along with the formation and vanishment of host-guest interaction is investigated. The reversible disassembly-reassembly of the polymer induced by light and the redox process are monitored by UV-vis and cyclic voltammetry, respectively. The interesting morphology differences between the monomer guest (G), supramolecular polymer (P), and light dissembled product pseudorotaxane (D1) are observed and analyzed. G conducts self-assembly into a short rod with average width of 83 nm due to the molecular amphipathy and π-π interaction between naphthalene nucleuses, while P exhibits 20 nm wide line morphology. Irradiating P with 365 nm light, the corresponding aggregation D1 shows as 35 nm wide short rod.

Branched 1,2,3-Triazolium-Functionalized Polyacetylene with Enhanced Conductivity.

Metathesis cyclopolymerization of mono- or bissubstituted 1,6-heptadiynes is undergone to generate the ionic polyacetylenes (iPAs) with branched 1,2,3-ttriazolium pendants, which possess relatively high intrinsic ionic conductivities of 1.4 × 10-5 -2.1 × 10-5 S cm-1 at 30 °C. The doping treatment with lithium bis(trifluoromethanesulfonyl)imide endows iPAs with enhanced ionic conductivities of 2.5 × 10-5 -4.3 × 10-5 S cm-1 . Further doping with iodine, iPAs show ionic and electronic dual conductivities of 4.5 × 10-5 -7.1 × 10-4 and 1.5 × 10-6 -4.5 × 10-6 S cm-1 , respectively. Therefore, the doped iPAs demonstrate the potential in the area of conducting polymers and polymeric electronics.

Nanostructured high-performance dielectric block copolymers.

A new type of insulating-conductive block copolymer was synthesized by metathesis polymerization. The copolymer can self-assemble into unique nanostructures of micelles or hollow spheres. It exhibits a high dielectric constant, low dielectric loss, and high stored/released energy density due to the strong dipolar and nano-interfacial polarization contributions.

Thermoresponsive AuNPs Stabilized by Pillararene-Containing Polymers.

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.

Ladder-like polyacetylene with excellent optoelectronic properties and regular architecture.

Novel double-stranded polyacetylene with a perylene bisimide bridge has been efficiently synthesized by metathesis cyclopolymerization of bis(1,6-heptadiyne) derivatives, and exhibited good solubility, highly thermal and oxidative stability, low LUMO energy levels, narrow bandgaps, and regular ladder-like architecture.

Functionalization of magnetic nanoparticles with dendritic-linear-brush-like triblock copolymers and their drug release properties.

Novel water-soluble dendritic-linear-brush-like triblock copolymer polyamidoamine-b-poly(2-(dimethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate) (PAMAM-b-PDMAEMA-b-PPEGMA)-grafted superparamagnetic iron oxide nanoparticles (SPIONs) were successfully prepared via a two-step copper-mediated atom transfer radical polymerization (ATRP) method. The macroinitiators were immobilized on the surface of Fe(3)O(4) nanoparticles via effective ligand exchange of oleic acid with the propargyl focal point PAMAM-typed dendron (generation 2.0, denoted as propargyl-D(2.0)) containing four carboxyl acid end groups, following a click reaction with 2'-azidoethyl-2-bromoisobutylate (AEBIB). PDMAEMA and PPEGMA were grown gradually from nanoparticle surfaces using the "grafting from" approach, which rendered the SPIONs soluble in water and reversed aggregation. To the best of our knowledge, this is the first report that describes the functionalization of magnetic nanoparticles with dendritic-linear-brush-like triblock copolymers. The modified nanoparticles were systematically studied via TEM, FT-IR, DLS, XRD, NMR, TGA, and magnetization measurements. DLS measurement confirmed that the obtained dendritic-linear-brush-like triblock copolymer-grafted SPIONs had a uniform hydrodynamic particle size of average diameter less than 30 nm. The dendritic-linear-brush-like triblock copolymer-grafted SPIONs possessed excellent biocompatibility by methyl tetrazolium (MTT) assays against NIH3T3 cells and hemolysis assays with rabbit erythrocytes. Furthermore, an anticancer drug, doxorubicin (Dox), was used as a model drug and loaded into the dendritic-linear-brush-like triblock copolymer-grafted SPIONs, and subsequently, the drug releases were performed in phosphoric acid buffer solution pH = 4.7, 7.4, or 11.0 at 37 °C. The results verify that the dendritic-linear-brush-like triblock copolymer-grafted SPIONs possess pH-responsive drug release behavior. The Dox dose of the loaded and free drug required for 50% cellular growth inhibition was 2.72 and 0.72 µm/mL, respectively, according to MTT assay against a Hella cell line in vitro. Therefore, on the basis of its biocompatibility and drug release effect, the modified SPION could provide a charming opportunity to design some excellent drug delivery systems for therapeutic applications.