RAFT‐Polymerization‐Induced Self‐Assembly and Reorganizations: Ultrahigh‐Molecular‐Weight Polymer and Morphology‐Tunable Micro‐/Nanoparticles in One Pot

A one‐pot method is introduced for the successful synthesis of narrow‐distributed (Đ = 1.22) vinyl polymer with both ultrahigh molecular weight (UHMW) (M _w = 1.31 × 10⁶ g mol⁻¹) and micro‐/nanomorphology under mild conditions. The method involves the following four stages: homogeneous polymerization, polymerization‐induced self‐assembly (PISA), PISA and reorganization, and PISA and multiple reorganizations. The key points to the production of UHMW polystyrene are to minimize radical termination by segregating radicals in different nanoreactors and to ensure sufficient chain propagation by promoting further reorganizations of these reactors in situ. This method therefore endows polymeric materials with the outstanding properties of both UHMW and tunable micro‐/nanoparticles under mild conditions in one pot.

     

Thieno[3,4‐c]Pyrrole‐4,6‐Dione and Dithiophene‐Based Conjugated Polymer for Organic Field Effect Transistors: High Mobility Induced by Synergic Effect of H‐Bond and Vinyl Linkage

Here, a conjugated polymer VTTPD based on thieno[3,4‐c]pyrrole‐4,6‐dione (TPD) and dithiophene with vinyl as linker is synthesized and characterized. Electrochemical and optical studies indicate the LUMO and HOMO energies of the polymer are −3.70 and −5.39 eV. Theoretical calculation with density functional theory suggests that H‐bonds are formed between the TPD carbonyl (O) and its neighboring vinyl (H) which benefit the planarity and π‐conjugation of the polymer backbone. Bottom contact bottom gate organic field effect transistor devices based on VTTPD are fabricated and examined in air. After annealing at 160 °C, the devices exhibit excellent performance of μ_h = 0.4 cm² V⁻¹ s⁻¹, I_on/off = 10⁶, Vth within −10 V to −5 V. Thin film morphologies before and after the annealing process are also investigated with XRD and AFM.

     

Novel Donor–Acceptor Polymer Containing 4,7‐Bis(thiophen‐2‐yl)benzo[c][1,2,5]thiadiazole for Polymer Solar Cells with Power Conversion Efficiency of 6.21%

In order to improve the solution processability of 4,7‐bis(thiophen‐2‐yl)benzo[c][1,2,5]thiadiazole (DTBT)‐based polymers, novel donor–acceptor polymer PTOBDTDTBT containing DTBT and benzo[1,2‐b:4,5‐b′]dithiophene (BDT) with conjugated side chain is designed and synthesized with narrow band gap 1.67 eV and low lying HOMO energy level −5.4 eV. The blend film of PTOBDTDTBT and PC₇₁BM exhibits uniform and smooth film with root‐mean‐square (RMS) surface roughness 1.15 nm because of the excellent solubility of PTOBDTDTBT when six octyloxy side chains are introduced. The hole mobility of the blend film is measured to be 4.4 × 10⁻⁵ cm² V⁻¹s⁻¹ by the space‐charge‐limited current (SCLC) model. The optimized polymer solar cells (PSCs) based on PTOBDTDTBT /PC₇₁BM exhibits an improved PCE of 6.21% with V_oc = 0.80 V, J_sc = 11.94 mA cm⁻² and FF = 65.10%, one of the highest PCE in DTBT containing polymers.

     

Increasing the Open‐Circuit Voltage in High‐Performance Organic Photovoltaic Devices through Conformational Twisting of an Indacenodithiophene‐Based Conjugated Polymer

A fused ladder indacenodithiophene (IDT)‐based donor–acceptor (D–A)‐type alternating conjugated polymer, PIDTHT‐BT, presenting n‐hexylthiophene conjugated side chains is prepared. By extending the degree of intramolecular repulsion through the conjugated side chain moieties, an energy level for the highest occupied molecular orbital (HOMO) of –5.46 eV – a value approximately 0.27 eV lower than that of its counterpart PIDTDT‐BT – is obtained, subsequently providing a fabricated solar cell with a high open‐circuit voltage of approximately 0.947 V. The hole mobility (determined using the space charge‐limited current model) in a blend film containing 20 wt% PIDTHT‐BT) and 80 wt% [6,6]‐phenyl‐C₇₁ butyric acid methyl ester (PC₇₁BM) is 2.2 × 10^–9 m² V^–1 s^–1, which is within the range of reasonable values for applications in organic photovoltaics. The power conversion efficiency is 4.5% under simulated solar illumination (AM 1.5G, 100 mW cm^–2).

     

Conjugated Polymer Composite Nanoparticles by Rapid Mixing

Composite nanoparticles from poly[(9,9‐di‐n‐octylfluoren‐2,7‐diyl)‐alt‐(benzo[2,1,3]thiadiazol‐4,8‐diyl)] (F8BT) and poly(9,9‐di‐n‐hexylfluoren‐2,7‐diyl) (PF) with embedded inorganic nanoparticles (TiO₂, CdSe, and CdSe/CdS) are prepared through kinetic trapping by rapid turbulent mixing in a multi‐inlet vortex mixer without the need for polymer functionalization. High contents of inorganic materials up to 50–60 wt% are realized for all composites. The influence of flow ratios, sodium dodecyl sulfate (SDS) concentration, and absolute flow rates on the particle size and morphology is studied. High water‐to‐THF ratios and high total flow rates around 2 m s⁻¹ yield particle sizes below 50 nm. By adjusting these parameters, controlled particle sizes between 30 to several hundred nanometers are obtained. Composite particles from CdSe/CdS and F8BT or PF show a strong quenching of the polymer emission and near exclusive emission from the inorganic nanocrystal, which indicates an efficient energy transfer with fluorescence quantum yields of 23% for the F8BT/CdSe/CdS composites and 21% for the PF/CdSe/CdS composites. The dispersions are colloidally stable for several months.

     

Light‐Induced Disintegration of Robust Physically Cross‐Linked Polymer Networks

Photodegradable physically cross‐linked polymer networks are prepared from self‐assembly of photolabile triblock copolymers. Linear triblock copolymers composed of poly (o‐nitrobenzyl methacrylate) and poly(ethylene glycol) (PEG) segments of variable molecular weights were synthesized using atom transfer radical polymerization. Triblock polymers with low‐molecular‐weight PEG segments form solid films upon hydration with robust mechanical properties including a Young's modulus of 76 ± 12 MPa and a toughness of 108 ± 31 kJ m⁻³. Triblock polymers with high‐molecular‐weight PEG segments form physically cross‐linked hydrogels at room temperature with a dynamic storage modulus of 13 ± 0.6 kPa and long‐term stability in hydrated environments. Both networks undergo photodegradation upon irradiation with long wave UV light.

     

Polymer‐Fullerene Network Formation via Light‐Induced Crosslinking

A facile and efficient methodology for the formation of polymer‐fullerene networks via a light‐induced reaction is reported. The photochemical crosslinking is based on a nitrile imine‐mediated tetrazole‐ene cycloaddition reaction, which proceeds catalyst‐free under UV‐light irradiation (λ_max = 320 nm) at ambient temperature. A tetrazole‐functionalized polymer (M_n = 6500 g mol⁻¹, Ð = 1.3) and fullerene C₆₀ are employed for the formation of the hybrid networks. The tetrazole‐functionalized polymer as well as the fullerene‐containing networks are carefully characterized by NMR spectrometry, size exclusion chromatography, infrared spectroscopy, and elemental analysis. Furthermore, thermal analysis of the fullerene networks and their precursors is carried out. The current contribution thus induces an efficient platform technology for fullerene‐based network formation.

     

Ion‐Conductive Properties of a Polymer Electrolyte Based on Ethylene Carbonate/Ethylene Oxide Random Copolymer

A random copolymer of ethylene oxide with CO₂, namely, poly(ethylene carbonate/ethylene oxide) (P(EC/EO)), has been synthesized as a novel candidate for polymer electrolytes. Electrolyte composed of P(EC/EO) and lithium bis(fluorosulfonyl)imide has an ionic conductivity of 0.48 mS cm⁻¹ and a Li transference number (t ₊) of 0.66 at 60 °C. To study ion‐conductive behavior of P(EC/EO)‐based electrolytes, the Fourier transform infrared (FT‐IR) technique is used to analyze the interactions between Li⁺ and functional groups of the copolymer. The carbonate groups may interact preferentially with Li⁺ rather than the ether groups in P(EC/EO). This study suggests that copolymerization of carbonate and flexible ether units can realize both high conductivity and t ₊ for polymer electrolytes. High‐performance P(EC/EO) electrolyte is expected to be a candidate material for use in all‐solid‐state batteries.

     

Balanced Ambipolar Poly(diketopyrrolopyrrole‐alt‐tetrafluorobenzene) Semiconducting Polymers Synthesized via Direct Arylation Polymerization

The synthesis of an ambipolar π‐conjugated copolymer consisting of alternating diketopyrrolopyrrole and tetrafluorobenzene via direct arylation polymerization (DAP) is reported. Two different combinations of monomers are investigated under various catalytic conditions for DAP. The target polymer obtained under an optimized catalytic condition shows minimal structural defects, a number‐average molecular weight of 33.2 kDa, and balanced electron and hole mobility of 1 × 10⁻² cm² V⁻¹ S⁻¹ in the organic field‐effect transistors fabricated and tested under ambient conditions.

     

Supramolecular Sky‐Blue Phosphorescent Polymer Iridium Complexes for Single‐Emissive‐Layer Organic Light‐Emitting Diodes

Novel supramolecular phosphorescent polymers (SPPs) are synthesized as a new class of solution‐processable electroluminescent emitters. The formation of these SPPs takes advantage of the efficient non‐bonding assembly between bis(dibenzo‐24‐crown‐8)‐functionalized iridium complex monomer and bis(dibenzylammonium)‐tethered co‐monomer, which is monitored by ¹H NMR spectroscopy and viscosity measurements. These SPPs show good film morphology and an intrinsic glass transition with a T_g of 94–116 °C. Noticeably, they are highly photoluminescent in solid state with quantum efficiency up to ca. 78%. The photophysical and electroluminescent properties are strongly dependent on the molecular structures of the iridium complex monomers.

     

Synthesis and Characterization of Poly(phenylacetylene)s with Ru(II) Bis‐Terpyridine Complexes in the Side‐Chain

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.

     

Improved Thin‐Film Transistor Performance Through a Melt of Poly(para‐phenyleneethynylene)

The performance of polymer field‐effect transistors (PFETs) based on short rigid rod semiconducting poly(2,5‐didodecyloxy‐p‐phenyleneethynylene) (D‐OPPE) is highlighted. The controlled heating and cooling of thin films of D‐OPPE allows for a recrystallization from the melt, boosting the performance of D‐OPPE‐based transistors. The improved film properties induced by controlled annealing lead to a hole field‐effect mobility around 0.014 cm² V⁻¹ s⁻¹, an on/off ratio of 10⁶, a sub‐threshold swing of 3 V dec⁻¹ and a threshold voltage of −35 V, employing a poly(methyl methacrylate) (PMMA) gate dielectric. Thus, PFETs out of D‐OPPE compete now with spin‐coated, polycrystalline poly(3‐hexylthiophene)‐based PFETs.

     

Synthesis and Gas Adsorption Properties of Tetra‐Armed Microporous Organic Polymer Networks Based on Triphenylamine

Two novel tetra‐armed microporous organic polymers have been designed and synthesized via a nickel‐catalyzed Yamamoto‐type Ullmann cross‐coupling reaction or Suzuki cross‐coupling polycondensation. These polymers are stable in various solvents, including concentrated hydrochloric acid, and are thermally stable. The homocoupled polymer YPTPA shows much higher Brunauer–Emmet–Teller‐specific surface area up to 1557 m² g⁻¹ than the copolymer SPTPA (544 m² g⁻¹), and a high CO₂ uptake ability of 3.03 mmol g⁻¹ (1.13 bar/273 K) with a CO₂/N₂ sorption selectivity of 17.3:1. Both polymers show high isosteric heats of CO₂ adsorption (22.7–26.5 kJ mol⁻¹) because the incorporation of nitrogen atoms into the skeleton of microporous organic polymers enhances the interaction between the pore wall and the CO₂ molecules. The values are higher than those of the porous aromatic frameworks, which contain neither additional polar functional groups nor nitrogen atoms, and are rather close to those of previously reported microporous organic polymers containing the nitrogen atoms on the pore wall. These data show that these materials would be potential candidates for applications in post‐combustion CO₂ capture and sequestration technology.

     

Synthesis of Hydroxy‐Functionalized Cyclic Olefin Copolymer and Its Block Copolymers with Semicrystalline Polyolefin Segments

Synthesis of hydroxy‐functionalized cyclic olefin copolymer (COC) is achieved with remarkably high activity (up to 5.96 × 10⁷ g‐polymer mol‐Ti⁻¹ h⁻¹) and controlled hydroxy group in a wide range (≈17.1 mol%) by using ansa‐dimethylsilylene (fluorenyl)(amido)titanium complex. The catalyst also promotes living/controlled copolymerization to afford novel diblock copolymers consisting of hydroxy‐functionalized COC and semicrystalline polyolefin sequence such as polyethylene and syndiotactic polypropylene, where the glass transition temperature of the norbornene/10‐undecen‐1‐ol segment and each block length are controlled by comonomer composition and copolymerization time, respectively.

     

Low‐Temperature Synthesis of Thermoresponsive Diblock Copolymer Nano‐Objects via Aqueous Photoinitiated Polymerization‐Induced Self‐Assembly (Photo‐PISA) using Thermoresponsive Macro‐RAFT Agents

Photoinitiated reversible addition‐fragmentation chain transfer (RAFT) dispersion polymerization of 2‐hydroxypropyl methacrylate is conducted in water at low temperature using thermoresponsive copolymers of 2‐(2‐methoxyethoxy) ethyl methacrylate and oligo(ethylene glycol) methacrylate (M_n = 475 g mol⁻¹) as the macro‐RAFT agent. Kinetic studies confirm that quantitative monomer conversion is achieved within 15 min of visible‐light irradiation (405 nm, 0.5 mW cm⁻²), and good control is maintained during the polymerization. The polymerization can be temporally controlled by a simple “ON/OFF” switch of the light source. Finally, thermoresponsive diblock copolymer nano‐objects with a diverse set of complex morphologies (spheres, worms, and vesicles) are prepared using this particular formulation.

     

High‐Efficiency Large‐Bandgap Material for Polymer Solar Cells

High‐molecular‐weight conjugated polymer HD‐PDFC‐DTBT with N‐(2‐hexyldecyl)‐3,6‐difluorocarbazole as the donor unit, 5,6‐bis(octyloxy)benzothiadiazole as the acceptor unit, and thiophene as the spacer is synthesized by Suzuki polycondensation. HD‐PDFC‐DTBT shows a large bandgap of 1.96 eV and a high hole mobility of 0.16 cm² V⁻¹ s⁻¹. HD‐PDFC‐DTBT:PC₇₁BM‐based inverted polymer solar cells (PSCs) give a power conversion efficiency (PCE) of 7.39% with a V_oc of 0.93 V, a J_sc of 14.11 mA cm⁻², and an FF of 0.56.

     

Fabricating Triple‐Sensitive Polymer Nano‐Aggregates via an Aqueous Iminoboronate Multicomponent Reaction

A triple‐sensitive polymer of poly(ethylene glycol)‐iminoboronate nitrobenzyl ethanediol chelate (PEG‐INEC) is efficiently fabricated via the convenient aqueous iminoboronate multi‐component reaction (MCR) of methoxypolyethylene glycol amine (mPEG‐NH₂), 2‐formylphenylboronic acid (FPBA), and bis(2‐nitrophenyl) ethanediol (BNPE, a photo‐cleavable nitrobenzyl alcohol derivate). The aqueous MCR synthetic procedure is followed using ¹H NMR and turbidity analysis. It is shown that polymer nano‐aggregates of PEG‐INEC in aqueous solution can be dissociated through the stimuli responsive reactions of the hydrophobic iminoboronate nitrobenzyl ethanediol chelates (INECs) when exposed to UV light, acid, and H₂O₂, respectively. Furthermore, upon the stimulation of combined triggers, the dissociation of polymer nano‐aggregates can be accelerated to different extents, resulting in the synergistic release of encapsulated hydrophobic molecules in water. The proposed facile and general method is quite desirable and of great importance in practical applications like drug and gene delivery.

     

A UV‐Cleavable Bottlebrush Polymer with o‐Nitrobenzyl‐Linked Side Chains

An ultraviolet (UV)‐cleavable bottlebrush polymer is synthesized using the “grafting‐onto” strategy by combining living radical polymerization and copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). In this approach, reversible addition‐fragmentation chain transfer polymerization is used to prepare a poly(methylacrylate) backbone with azide side groups, while atom transfer radical polymerization is employed to prepare polystyrene (PS) side chains end‐functionalized with o‐nitrobenzyl (UV‐cleavable) propargyl groups. CuAAC is then used to graft PS side chains onto the polymer backbone, producing the corresponding bottlebrush polymers with UV‐cleavable PS side chains. The formation of the bottlebrush polymer is characterized by ¹H nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), and Fourier transform infrared spectroscopy. The cleavage behavior of the bottlebrush polymer is monitored in tetrahydrofuran solution under UV irradiation by GPC and viscosity measurements.

     

Luminescent Polymer Consisting of 9,12‐Linked o‐Carborane

The synthesis of novel luminescent polymer containing p‐phenylene‐ethynylene and 9,12‐linked o‐carborane units alternately in the main chain is reported. The obtained polymer exhibits intense blue photoluminescence, providing the first insights into the optical properties of a 9,12‐disubstituted o‐carborane dye.  π‐Conjugated substituent at 9 and/or 12‐positions in o‐carborane is electrically independent, and both the HOMO and the LUMO levels slightly increase, whereas LUMO of the π‐conjugated substituent at 1 and/or 2‐positions in o‐carborane decrease.  Thus, it is deduced that polymers consisting of the 9,12‐linked o‐carborane unit are able to be applied as light‐emitting materials.

     

A Neutral Supramolecular Hyperbranched Polymer Fabricated from an AB2‐Type Copillar[5]arene

A heterotritopic copillar[5]arene monomer by introducing effective neutral guest moieties (methylene chains end‐capped with cyano and triazole groups) to a pillar[5]arene macrocycle is prepared. This well‐designed AB₂‐type copillar[5]arene contains strong host–guest recognition motifs that are connected with relatively flexible and long linkers, thus efficiently assembles to form supramole­cular hyperbranched polymer (SHP) in chloroform solution, which is characterized by various techniques including ¹H NMR, DOSY, viscosity, DLS, and TEM. Particularly, this supramolecular polymer can be effectively depolymerized by adding a competitive butanedinitrile guest.