A One-Step Strategy for End-Functionalized Donor–Acceptor Conjugated Polymers

Enzyme-Triggered Degradation of Supramolecularly Cross-Linked Polymersomes of Azobenzene-Based Polyurethane: Cell-Selective Anticancer Drug Release

Enzyme-responsive self-assembled nanostructures for drug delivery applications have gained a lot of attention, as enzymes exhibit dysregulation in many disease-associated microenvironments. Azoreductase enzyme levels are strongly elevated in many tumor tissues; hence, here, we exploited the altered enzyme activity of the azoreductase enzyme and designed a main-chain azobenzene-based amphiphilic polyurethane, which self-assembles into a vesicular nanostructure and is programmed to disassemble in response to a specific enzyme, azoreductase, with the help of the nicotinamide adenine dinucleotide phosphate (NADPH) coenzyme in the hypoxic environment of solid tumors. The vesicular nanostructure sequesters, stabilizes the hydrophobic anticancer drug, and releases the drug in a controlled fashion in response to enzyme-triggered degradation of azo-bonds and disruption of vesicular assembly. The biological evaluation revealed tumor extracellular matrix pH-induced surface charge modulation, selective activated cellular uptake to azoreductase overexpressed lung cancer cells (A549), and the release of the anticancer drug followed by cell death. In contrast, the benign nature of the drug-loaded vesicular nanostructure toward normal cells (H9c2) suggested excellent cell specificity. We envision that the main-chain azobenzene-based polyurethane discussed in this manuscript could be considered as a possible selective chemotherapeutic cargo against the azoreductase overexpressed cancer cells while shielding the normal cells from off-target toxicity.

Multi-component Copolymerized Donors enable Frozen Nano-morphology and Superior Ductility for Efficient Binary Organic Solar Cells

Multi-component copolymerized donors (MCDs) have gained significant interest and have been rapidly developed in flexible organic solar cells (f-OSCs) in recent years. However, ensuring the power conversion efficiency (PCE) of f-OSCs while retaining ideal mechanical properties remains an enormous challenge. The fracture strain (FS) value of typical high-efficiency blend films is generally less than 8 %, which is far from the application standards of wearable photovoltaic devices. Therefore, we developed a series of novel MCDs after meticulous molecular design. Among them, the consistent MCD backbone and end-capped functional group formed a highly conjugated molecular plane, and the solubilization and mechanical properties were effectively optimized by modifying the proportion of solubilized alkyl chains. Consequently, due to the formation of entangled structures with a frozen blend film morphology considerably improved the high ductility of the active layer, P10.8/P20.2-TCl exhibited efficient PCE in rigid (18.53 %) and flexible (17.03 %) OSCs, along with excellent FS values (16.59 %) in pristine films, meanwhile, the outstanding FS values of 25.18 % and 12.3 % were achieved by P10.6/P20.4-TCl -based pristine and blend films, respectively, which were one of the highest records achieved by end-capped MCD-based binary OSCs, demonstrating promising application to synchronize the realization of high-efficiency and mechanically ductile flexible OSCs.

Cisplatin-Conjugated Polyurethane Capsule for Dual Drug Delivery to a Cancer Cell

This paper describes the synthesis of a polymer-prodrug conjugate, its aqueous self-assembly, noncovalent encapsulation of a second drug, and stimuli-responsive intracellular dual drug delivery. Condensation polymerization between a functionalized diol and a commercially available diisocyanate in the presence of poly(ethylene glycol) hydroxide (PEG-OH) as the chain stopper produces an ABA-type amphiphilic block copolymer (PU-1) in one pot, with the middle hydrophobic block being a polyurethane containing a pendant tert-butyloxycarbonyl (Boc)-protected amine in every repeating unit. Deprotection of the Boc group, followed by covalent attachment of the Pt(IV) prodrug using the pendant amine groups, produces the polymer-prodrug conjugate PU-Pt-1, which aggregates to nanocapsule-like structures in water with a hydrophilic interior. In the presence of sodium ascorbate, the Pt(IV) prodrug can be detached from the polymer backbone, producing the active Pt(II) drug. Cell culture studies show appreciable cell viability by the parent polymer. However, the polymer-prodrug conjugate nanocapsules exhibit cellular uptake and intracellular release of the active drug under a reducing environment. The capsule-like aggregates of the polymer-prodrug conjugate were used for noncovalent encapsulation of a second drug, doxorubicin (Dox), and Dox-loaded PU-Pt-1 aggregate showed a significantly superior cell killing efficiency compared to either of the individual drugs, highlighting the promising application of such a dual-drug-delivery approach.

Direct Correlation between the Secondary Structure of an Amphiphilic Polymer and Its Prominent Antiviral Activity

An amphiphilic segmented polyurethane (F-PU-S), with pendant sulfate groups and a flexible hydrocarbon backbone, exhibits intrachain H-bonding-reinforced folding and hierarchical assembly, producing an anionic polymersome with efficient display of sulfate groups at the surface. It shows an excellent antiviral activity against Sendai virus (SV) by inhibiting its entry to the cells. Mechanistic investigation suggests fusion of the SV and the polymersome to produce larger particles in which neither the folded structure of the polymer nor the fusogenic property of the SV exists anymore. In sharp contrast, a structurally similar polymer R-PU-S, in which the chain folding pathway is blocked by replacing the flexible C6 chain with a rigid cyclohexane chain in the backbone, cannot form a similar polymersome structure and hence does not exhibit any antiviral activity. On the other hand, the third polymer (F-PU-C), which is similar to F-PU-S except for the pendant anionic groups (carboxylate instead of sulfate), also fails to exhibit any antiviral activity against SV, confirming the essential role of the chain folding as well as the pendant sulfate groups for the fusion-induced antiviral activity of F-PU-S, which provides an important structural guideline for developing new antiviral polymers.

A Hierarchical (Macro)molecular Assembly Assisted by Donor-Acceptor Charge-Transfer Interactions Exhibiting Room-Temperature Ferroelectricity

This communication reveals co-assembly of an electron-deficient naphthalene-diimide (NDI)-appended polyurethane (P1) and electron-rich pyrene (Py), forming an organogel with prominent room-temperature ferroelectricity. In a non-polar medium, intra-chain hydrogen-bonding among the urethane groups of P1 produces a folded structure with an array of the NDIs in the periphery, which intercalate Py by charge-transfer (CT)-interaction. Such CT-complexation enables slow crystallization of the peripheral hydrocarbons, causing gelation with nanotubular morphology, in which the wall consists of the alternating NDI-Py stack. Such D-A assembly exhibits ferroelectricity (saturation polarization P_s ≈0.8 μC cm^-2 and coercive field E_c ≈8 kV cm^-1 at 500 V and 10 Hz frequency) with Curie temperature (T_c ) of ≈350 K, which can be related to the disassembly of the CT-complex. In the absence of Py, P1 forms spherical aggregates, showing dielectric behaviour.

Stretchable and Degradable Semiconducting Block Copolymers

This paper describes the synthesis and characterization of a class of highly stretchable and degradable semiconducting polymers. These materials are multi-block copolymers (BCPs) in which the semiconducting blocks are based on the diketopyrrolopyrrole (DPP) unit flanked by furan rings and the insulating blocks are poly(ε-caprolactone) (PCL). The combination of stiff conjugated segments with flexible aliphatic polyesters produces materials that can be stretched >100%. Remarkably, BCPs containing up to 90 wt% of insulating PCL have the same field-effect mobility as the pure semiconductor. Spectroscopic (ultraviolet-visible absorption) and morphological (atomic force microscopic) evidence suggests that the semiconducting blocks form aggregated and percolated structures with increasing content of the insulating PCL. Both PDPP and PCL segments in the BCPs degrade under simulated physiological conditions. Such materials could find use in wearable, implantable, and disposable electronic devices.

A one-pot strategy to improve end-capping efficacy in Stille poly-condensations

A reproducible synthetic method affording end-functionalized conjugated polymers via Stille polycondensations based upon end-capping reagent relative kinetics is presented.

Synthetic approaches towards structurally-defined electrochemically and (photo)redox-active polymer architectures

This review details synthetic strategies leading to structurally-defined electrochemically and (photo)redox-active polymer architectures,e.g.block, graft and end functionalized (co)polymers.

A remarkable impact of a minor structural variation in the chain-end on the hierarchical self-assembly of a polymeric foldamer

This article elucidates a remarkable end group effect on the macroscopic assembly pathway of chain folded polyurethanes (PU) PU-2 and PU-3, both of which contain a linear PU chain appended with n-type semiconducting naphthalene-diimide (NDI) chromophores.

Synthesis of heteroarenes dyads from heteroarenes and heteroarylsulfonyl chlorides via Pd-catalyzed desulfitative C–H bond heteroarylations

We report palladium-catalyzed synthesis of heteroarenes dyads using heteroarylsulfonyl chlorides as coupling partners. The C–H bond functionalizations occurred at α-position with pyrroles and furans, while at β-position with thiophenes.

Long-lived charge carrier generation in ordered films of a covalent perylenediimide-diketopyrrolopyrrole-perylenediimide molecule

The photophysics of a covalently linked perylenediimide-diketopyrrolopyrrole-perylenediimide acceptor-donor-acceptor molecule (PDI-DPP-PDI, 1) were investigated and found to be markedly different in solution versus in unannealed and solvent annealed films. Photoexcitation of 1 in toluene results in quantitative charge separation in τ = 3.1 ± 0.2 ps, with charge recombination in τ = 340 ± 10 ps, while in unannealed/disordered films of 1, charge separation occurs in τ < 250 fs, while charge recombination displays a multiexponential decay in ∼6 ns. The absence of long-lived, charge separation in the disordered film suggests that few free charge carriers are generated. In contrast, upon CH₂Cl₂ vapor annealing films of 1, grazing-incidence X-ray scattering shows that the molecules form a more ordered structure. Photoexcitation of the ordered films results in initial formation of a spin-correlated radical ion pair (electron-hole pair) as indicated by magnetic field effects on the formation of free charge carriers which live for ∼4 μs. This result has significant implications for the design of organic solar cells based on covalent donor-acceptor systems and shows that long-lived, charge-separated states can be achieved by controlling intramolecular charge separation dynamics in well-ordered systems.

Stimuli responsive triblock copolymers by chain-growth polymerization from telechelic macroinitiators prepared via a step-growth polymerization

The synthesis of stimuli-responsive ABA tri-block copolymers using a step-growth polmerization followed by a chain-growth polymerization.

Chain-growth polycondensation of perylene diimide-based copolymers: a new route to regio-regular perylene diimide-based acceptors for all-polymer solar cells and n-type transistors

Chain-growth tin-free room temperature polymerization is reported which leads to perylene diimide-based n-type polymers suitable for solar cell and transistor applications.

Monotelechelic poly(p-phenylenevinylene)s by ring opening metathesis polymerisation

High molecular weight poly(p-phenylenevinylene)s with a single reactive end group are reported that act as excellent macroinitiators in block copolymer synthesis.

Charge transport behaviors of end-capped narrow band gap polymers in bottom-contact organic field-effect transistors

The ends of conjugated polymer chains were capped with thiophene units to enhance intermolecular packing and decrease device hysteresis by removing charge trap sites.