Initiated Radical Polymerization Research Articles

Ligand Dissociation of Metal-Complex Photocatalysts toward pH-Photomanipulation in Dynamic Covalent Hydrogels for Printing Reprocessable and Recyclable Devices.

Dynamic covalent hydrogels are gaining attention for their potential in smart materials, soft devices, electronics, and more thanks to their impressive mechanical properties, biomimetic structures, and dynamic behavior. However, a significant challenge lies in designing precise and efficient dynamic photochemistry for their preparation, allowing for complex structures and control over the dynamic process. Herein, we propose a general and straightforward orthogonal dynamic covalent photochemistry strategy for preparing high-performance printable dynamic covalent hydrogels, thereby broadening their advanced applications. This photochemical strategy uses a bifunctional photocatalyst to initiate radical polymerization and release ligands through a rapid light-mediated dissociation mechanism. This process leads to a controlled increase in system pH from mildly acidic to alkaline conditions within one hundred seconds, which in turn triggers the pH-sensitive model reactions of boronic acid/diol complexation and Knoevenagel condensation. The orthogonal photochemistry enables the formation of interpenetrated and conjoined networks, significantly enhancing the mechanical properties of the hydrogels. The reversible bonds formed during the process, i.e., boronic ester and unsaturated ketone bonds, confer excellent self-healing, reprocessable, and recyclable properties on the hydrogels through photochemical pH variations. Furthermore, this rapid, controlled fabrication process and dynamic behavior are highly compatible with printing techniques, enabling the design of adaptive and recyclable sensors with different structures. These advancements are promising for various material science, medicine, and engineering applications.

Precise synthesis of three-arm star polymethacrylates with high emission efficiency both in solution and in the solid state

Organic/polymeric fluorescent materials with bright emission both in solution and in the solid state have garnered growing interest in biological and optoelectronic fields. Herein, triphenylamine-derived boron ketoimine (TPA-BKI-3Br) was utilized as the initiator for atom transfer radical polymerization (ATRP) to prepare dual-state emission three-arm star polymethacrylates. Due to the intramolecular charge transfer (ICT) effect and highly distorted structure of the TPA-BKI unit, as well as the polymer arms constraining intramolecular motions, the resultant polymers displayed significant emission in solution. In the aggregated and solid states, the photophysical characteristics of the resultant polymethacrylates were notably impacted by the space charge transfer between the TPA-BKI unit and polymer chains. In addition, the TPA-BKI-based poly(2-(dimethylamino)ethyl methacrylate) (TPA-BKI-(PDMAEMA)3) exhibited fluorescence responses to temperature variations owing to the presence of dimethylamino group. This study presents an approach for the advancement of dual-state emission polymeric materials.

Transformation of metoprolol in UV/PDS process: Role and mechanisms of degradation and polymerization

Advanced oxidation processes for the treatment of organic pollutants in wastewater suffer from difficulties in mineralization, potential risks of dissolved residues, and high oxidant consumption. In this study, radical-initiated polymerization is dominated in an UV/peroxydisulfate (PDS) process to eliminate organic pollutant of pharmaceutical metoprolol (MTP). Compared with an ideal degradation-based UV/PDS process, the present process can save four fifths of PDS consumption at the same dissolved organic carbon removal of 47.3%. Simultaneously, organic carbon can be recovered from aqueous solution by separating solid polymers at a ratio of 50% of the initial chemical oxygen demand. The chemical structure of products was analyzed to infer the transformation pathways of MTP. Unlike previous studies on simple organic pollutants that the polymerization can occur independently, the polymerization of MTP is dependent on the partial degradation of MTP, and the main monomer in polymerization is a dominant degradation product (4-(2-methoxyethyl)-phenol, denoted as DP151). The separated solid polymers are formed by repeated oxidation and coupling of DP151 or its derivatives through a series of intermediate oligomers. This proof-of-concept study demonstrates the advantage of polymerization-dominated mechanism on dealing with large organic molecules with complex structures, as well as the potential of UV/PDS process for simultaneous organic pollution reduction and organic carbon recovery from aqueous solution.

Polymerizable deep eutectic solvents: Convenient reactive dispersion media for the preparation of novel multi-walled carbon nanotubes-based functional materials

A new straightforward and green approach for the covalent functionalization of multi-walled carbon nanotubes (MWCNTs) was developed. This carbon nanostructure was efficiently derivatized by polymerizing proper deep eutectic monomers (DEM), a subclass of deep eutectic solvents (DES), based on a series of mono- and bis-vinyl imidazolium salts endowed with different functional groups (–OH, –NH2, –NH3+Br–) in the side chain or in the spacer. Herein, DEM systems played a triple role as convenient dispersion media for MWCNTs, efficient reactive systems, and also as structure-directing agents for the radical-initiated polymerization process onto the surface of MWCNTs. In addition, the new methodology allowed obtaining highly functionalized hybrid materials, as shown by thermogravimetric analyses, in short reaction times (<1h). Transmission electron microscopy (TEM) revealed that the polymeric network orderly develops along the surface of the nanotubes, which act as templating agent for both mono- and bis-vinyl imidazolium salts, despite the random nature of the polymerization process for the latter species. This new functionalization strategy of MWCNTs stands out for its environmentally friendly and time-saving nature leading to the formation of materials with significant potential for applications in a plethora of research fields. As a proof of their possible application, we tested these new hybrid materials as recoverable and recyclable catalysts for the conversion of CO2 into cyclic carbonates under solvent-free conditions, showing good catalytic performances, even in the absence of additional co-catalysts.

Synthesis and characterization of graft copolymer hydrogel by “grafting from” atom transfer radical polymerization using brominated macro monomeric initiator and investigation of hydrogel properties

AbstractIn this study, poly(ɛ-caprolactone-g-2-hydroxy ethyl methacrylate) [P(CL-g-HEMA)] graft copolymer hydrogels were successfully synthesized through multi-step reactions. For this purpose, firstly, hydroxyl-terminated poly(ɛ-caprolactone) (PCL-OH) was obtained by ring-opening polymerization (ROP) method of ɛ-caprolactone using 3-chlor-1,2-propanediol initiator, which is suitable for ring-opening polymerization method. Then, from the reaction of synthesized PCL-OH and 3-bromopropionyl chloride, a new brominated poly(ɛ-caprolactone) (PCL-Br) was synthesized for use as a functionalized atom transfer radical polymerization (ATRP) initiator. Poly(ɛ-caprolactone-g-2-hydroxy ethyl methacrylate) [P(CL-g-HEMA)] graft copolymer hydrogels were synthesized by “grafting from” atom transfer radical polymerization (ATRP) of 2-hydroxy ethyl methacrylate (HEMA) presence the new synthesized functionalized ATRP initiator (PCL-Br) and hydrogel properties were investigated. The synthesized functionalized initiators and graft copolymer hydrogel were characterized by spectroscopic methods such as 1H-NMR, FT-IR, TGA, DSC and SEM. The observation of two different decomposition temperatures, respectively, from the TGA analysis results may support the formation of the biblock graft copolymer. A glass transition temperature (Tg) of the graft copolymer hydrogel was found by DSC, and this value is between the Tg values of the homopolymers forming the graft copolymer hydrogel. Water swelling values of graft copolymer hydrogels were measured and calculated every 24 h in pure water with pH = 7 at from + 4 to 65 °C. Considering the weight of dry graft copolymer hydrogels, it was seen that water was absorbed at most at + 4 °C. As the temperature increased, the water absorption or swelling of the hydrogel decreased.

Enhanced dye removal using montmorillonite modified with graphene quantum dots in sustainable salep nanocomposite hydrogel

This research investigated the utilization of graphene quantum dot/montmorillonite (GQD/MMT) as an effective nanofiller in a hydrogel composed of salep biopolymer. The semi-IPN hydrogel was synthesized using salep as the substrate, acrylamide (AAm) as the monomer, ammonium persulfate (APS) as an initiator in free radical polymerization, and N,N'-methylenebisacrylamide (MBA) as a cross-linking agent. The hydrogels were applied to remove safranin (SA), methylene blue (MB), crystal violet (CV), methyl green (MG), congo red (CR), and malachite green (MG) dyes from the water. The diverse properties were analyzed using a scanning electron microscope, fourier infrared spectroscopy, mapping, energy dispersive spectroscopy, weighing analysis, X-ray diffraction, and thermal stability analyses. The optimism of the prepared adsorbent in dye absorption was evaluated by measuring the swelling amount, pH impact, adsorbent dosage, and contact time. The adsorption calculations were described using kinetics and isotherm models. The results indicated that the Langmuir isotherm model (R2 = 99.6) and the pseudo-second-order kinetic model (R2 = 99.9) provided the best fit for the absorption process of MB. The presence of additional amounts of GQD/MMT had a reciprocal effect on the adsorption efficiency due to the accumulation of GQD/MMT in the semi-interpenetrating polymer network (semi-IPN (structure. The findings revealed that the samples exhibited high thermal stability, and the absorption process was primarily chemical. Furthermore, the nanocomposite hydrogels demonstrated distinct mechanisms for absorbing anionic dye (CR) and cationic dye (MB). Under optimal conditions, using 7 wt% GQD/MMT at a concentration of 5 ppm, pH = 7, an adsorbent dosage of 50 mg, at room temperature, and a contact time of 90 min, the maximum removal efficiencies were achieved: MB (96.2%), SA (98.2%), MG (86%), CV (99.8%), MG (95.8%), and CR (63.4%). These results highlight the adsorbent's high absorption capacity, rapid removal rate, and reusability, demonstrating its potential as an eco-friendly and cost-effective solution for removing dyes from water.

Dual role of alkoxyamine-functionalized lamellar materials in the synthesis of hybrid polymers

Alkoxyamine-functionalized polysilsesquioxane lamellar materials were used as fillers and radical polymerization initiator in the synthesis of nanocomposites. This work is divided into three parts: (i) the synthesis and the characterization of functionnalized-lamellae, (ii) the study of their delamination and (iii) the polymerization leading to the nanocomposites. The presence of covalently bonded siloxane filler reinforced the polystyrene. In addition, the EPR analysis showed that alkoxyamine groups were still present on the nanocomposite and could be homolyzed under thermal condition to enable further potential functionalisations.

Preparation and properties of spirulina protein graft modified adhesive, used in plywood wood bonding

In this study, glycidyl methacrylate (GMA) was grafted onto spirulina protein isolate (SPPI), a novel raw material, to increase its water resistance and create an eco-friendly wood adhesive. Papain used as the denaturing agent in the grafting procedure and ammonium persulfate (APS) as the radical polymerization initiator. Based on the water-resistant bonding strength of the grafted polymer, the factors that affect the grafting reaction were analyzed and the reactive conditions were optimized single-factor experiments. According to the most optimum reaction conditions and the optimal preparation conditions, the SPPI-GMA adhesive showed that the wet strength 1.45 MPa was improved around 210% (the dry strength improved around 100%) compared to the untreated SPPI. The results of Fourier transform infrared spectroscopy (FT-IR),13C-Nuclear magnetic resonance (13C-NMR) and X-ray diffraction (XRD) indicated that the GMA had been grafted on the SPPI successfully. In addition, the cure temperature of SPPI-GMA adhesive was analyzed by the Differential scanning calorimetry (DSC). Thus, the SPPI- GMA adhesive has the potential to be applied to the wood industry.

Cyclic macromonomer from a multifunctional atom transfer radical polymerization initiator via sulfoxide-based vinyl protection

A novel synthetic approach to vinyl-functionalized cyclic macromolecules via sulfoxide chemistry.

Freshness Indicating Substance Sensor in Meat Using Molecularly Imprinted Carbon Paste Electrode

Fresh fish and meat are rich in adenosine-triphosphate (ATP), which over time is converted via adenosine-diphosphate (ADP) and adenosine-monophosphate (AMP) into the flavor component inosinate, which, with more time, is converted into the unpleasant-tasting components inosine and hypoxanthine . These six substances are indicators to measure the freshness and maturity of meat and fish. If these substances can be easily measured at the distribution site, fair trade based on objective judgments of freshness and ripeness will become possible.We are attempting a simple disposable sensor using molecularly imprinted polymer-immobilized carbon paste (MIP-CP). Graphite particles immobilized with a radical polymerization initiator were immersed in a solution of the target materials, inosine, methacrylamidophenylboronic acid, methacrylic acid, and methylenebisacrylamide, and graft polymerized by photoirradiation. The particles were washed with hydrochloric acid to remove the inosine to obtain graphite covered with an MIP layer. This was mixed with ferrocene-containing silicone oil to form a paste and applied to a commercial carbon screen-printed electrode (Zensor, Taipei) to obtain disposable electrodes. Differential pulse voltammetry was performed in buffer solutions containing inosine or sodium inosinate; the current at 0.9 V vs. Ag/AgCl increased with increasing inosine concentration, but there was little sensitivity to sodium inosinate concentration as shown in the Figure. These results indicate that a sensor has been created that shows a highly selective response to inosine, which is the template for MIP. The measurement takes about 30 seconds. We will continue to improve the reproducibility and develop a sensor that can detect the other five indicator substances in the same way.This work is partially supported by Small-Business Innovation Research (SBIR) Program of Bio-oriented Technology Research Advancement Institution (BRAIN), in Japan (SU23A03). Figure 1

A Disposable Sensor for Rapid Histamine Detection in Fish Using Molecularly Imprinted Carbon Paste Electrode

Introduction: Histamine (HM), a toxic compound, is produced due to an enzymatic reaction when histidine (HS)-rich red fish such as tunas and other fish and their processed products are improperly stored, e.g., leaving them at room temperature. With the increasing popularity of raw fish consumption, HM analysis is mandatory for these fish in various countries. However, the conventional immunoassay method is time-consuming, costly, and technically demanding, burdening wholesalers heavily.Molecularly Imprinted Polymers-based materials are attractive materials for sensor fabrication due to their high selectivity, stability, and ease of production. In this study, we attempted to develop a Molecularly Imprinted Polymer grafted Carbon Paste (MIP-CP) for histamine sensing. Experimental Methods First, a radical polymerization initiator was fixed on the surface of graphite particles [1]. Next, histamine dihydrochloride, itaconic acid, and ethylene glycol dimethacrylate (EDMA) were dissolved in a mixture of distilled water and dimethylformamide to prepare a polymerization solution. The polymerization solution and initiator-fixed graphite were placed in a quartz tube and irradiated with a xenon lamp for 1 hr. HM was extracted and removed using acetic acid. MIP-CP was prepared by mixing MIP-grafted graphite and silicon oil containing ferrocene in a 7:3 weight ratio. Non-imprinted polymer (NIP)-CP was also prepared using the same procedure, except that HM was not added.Differential pulse voltammetry (DPV) was performed with electrodes packed with the obtained MIP-CPs on a disposable chip [2]. The performance of the HM sensor was evaluated based on the relationship between the oxidation current of ferrocene and HM concentration. (Measurement range 0 μg/mL~100 μg/mL) Experimental results The dependence of the oxidation current density on HM concentration at the NIP and MIP electrodes was confirmed (0.0085 μA-mL/μg, R²=0.9357). The increase in current density with increasing HM concentration at the MIP-CP electrode was more than three times greater than at the NIP-CP electrode. This confirmed that MIP-CP exhibited current changes corresponding to the interaction between HM and HM-imprinted sites. Furthermore, the current increased linearly with increasing HM concentration from 0-100 µg/mL. This dynamic range includes 50 µg/mL, which is considered the lower limit of acceptable Hm concentration in fish meat.However, the current value was constant for HS concentration at 0.75 µA over the range of 40-100 µg/mL and below. Therefore, the sensor is saturated with HS at concentrations above 40 µg/mL, and histidine interference can be excluded by subtracting 0.75 µA from the current value obtained when measuring the fish meat sample. Conclusion We successfully developed a reagentless, disposable histamine sensor using MIP-CP, which provides a rapid, reliable, and cost-effective method for histamine detection in fish.

Linear, Y- and Ψ-shaped poly(2-(dimethylamino)ethyl methacrylate) and poly(methyl methacrylate) brushes prepared by surface-initiated polymerization from a homologous series of ATRP initiators

A series of 3 homologous surface-anchored initiators for atom transfer radical polymerization has been used to graft linear, Y- and Ψ-shaped poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(methyl methacrylate) (PMMA) brushes from silicon surfaces. The film thicknesses of these architecturally different polymer brushes could be tuned both by controlling the polymerization time, as well as (as was shown for the polymerization of 2-(dimethylamino)ethyl methacrylate) by changing the monomer concentration. The library of linear, Y- and Ψ-shaped PDMAEMA and PMMA brushes was used to investigate the possible impact of polymer architecture on the swelling properties as well as the degrafting behavior of these surface-grown polymer films. The swelling of the PDMAEMA and PMMA brushes in PBS, respectively, acetone as a solvent was studied by ellipsometry. These experiments revealed a smaller swelling ratio for Y-shaped polymer brushes, as compared to linear analogues of comparable dry film thickness. Degrafting experiments were conducted with linear, Y- and Ψ-shaped PDMAEMA brushes in PBS. These experiments revealed a 2-fold, respectively, 3-fold increase in the initial rate constant of degrafting for the Y- and Ψ-shaped PDMAEMA brushes as compared to the linear analogues.

High-Sensitivity Mechanochromic Sensor Using Core-Shell Colloidal Crystals

The Colloidal Crystals-based mechanochromic sensor changes color as the arrangement of colloidal particles changes in response to mechanical deformation, which can be detected through optical measurement. This type of sensor can be used in various applications, such as automobile collision detection, structural deformation detection, and medical equipment, among others. In this study, we prepared a stretchable film by dispersing surface-functionalized colloidal particles in an elastic polymer matrix. Surface of silica colloidal particle was modified with an initiator for Atom Transfer Radical Polymerization (ATRP), followed by surface-initiated ATRP of poly(t-butyl methacrylate) (PtBMA). The core-shell colloidal particles were composited with various acrylic monomers, to fabricate crystalline colloidal array which transforms to elastic film by photopolymerization exhibiting structural color. The prepared film showed a clear color change for deformation within 10%, and the peak reflectance showed more than 30%.

Facile fabrication of titanium atomic modification polyimide‑silicone coatings via moisture/thermal dual curing for high temperature protection

The development of coatings with high thermal resistance and strong adhesion is desirable and challenging. Herein, we firstly reported a novel bismaleimide silicone (PMI-HSi) oligomer as well as the matching titanium-containing phthalate curing agent (PAEs). Subsequently, PMI-HSi and PAEs are semi-cured by a de-ethanolization reaction in humid ambient atmosphere. Resultant prepolymer molecular skeletons comprise acylimine bonds yielding strong hydrogen bonds, benzene rings, and titanium atoms, which facilitates the stability of the prepared coatings in high-temperature conditions. Ultimately, the final coating was successfully obtained via thermal initiated radical polymerization. The DTG results indicated that the residual carbon content of PMI-HSi@PAEs50% is as high as 63.9 %. And the Td5%, Td30% and THRI of PMI-HSi@PAEs50% were separately increased by 142.2 %, 29.2 % and 47.9 % compared with the control group. It is worth noting that PMI-HSi@PAEs50% can remain stable at a high temperature up to 600 °C, and no color changes and cracks appeared on the coating surface. All these results indicate that the as-prepared coatings exhibited excellent high temperature stability. In addition, due to the introduction of PAEs, the adhesion of PMI-HSi@PAEs50% reaches the highest grade of 0 and the hardness reaches 5H. Meanwhile, the reinforcement mechanisms were elucidated in detail. Overall, the as-prepared coating possesses high temperature resistance, strong adhesion, and great hardness, which possesses enormous potential for applications in the field of high-temperature protection.

Characterization of well‐defined PHEMA‐based bottlebrushes with controlled chain length and grafting density

AbstractBottlebrushes with controlled horizontal‐ and vertical‐axis scales, which have a high density of graft chains on their main chains, are useful as a nanomaterial. The properties of bottlebrushes depend on the polymer‐type, ‐chain length, and grafting density. We fabricate well‐defined bottlebrushes based on poly(2‐hydroxyethyl methacrylate) (PHEMA) using the grafting from method. Macroinitiators with different compositions of an atom transfer radical polymerization (ATRP) initiator group are prepared, and two bottlebrushes are consequently synthesized by ATRP of HEMA with the macroinitiator: a concentrated bottlebrush with graft chains on the repeating units and a semi‐dilute bottlebrush with graft chains on approximately 10%. The hydrodynamic and gyration radii of the concentrated‐ and semi‐dilute bottlebrushes are Rh = 9.2 nm (Rg = 24.9 nm) and Rh = 69.1 nm (Rg = 130 nm), respectively. The shape factors (Rg/Rh) of these bottlebrushes indicate both solid‐rods. The virial coefficient of semi‐dilute bottlebrush, calculated from static light scattering measurements, is higher than that of concentrated bottlebrush, owing to the flexibility and solvation structure. The grafting density play a more prominent role than the graft‐chain length in the excluded volume effect of the bottlebrush. These results provide useful insights for the construction of polymethacrylate‐based bottlebrushes with specific hydrodynamic properties.

Interfacial mechanism of hydrogel with controllable thickness for stable drag reduction

Surface wettability plays a significant role in reducing solid-liquid frictional resistance, especially the superhydrophilic/hydrophilic interface because of its excellent thermodynamic stability. In this work, poly(acrylic acid)-poly(acrylamide) (PAA–PAM) hydrogel coatings with different thicknesses were prepared in situ by polydopamine (PDA)-UV assisted surface catalytically initiated radical polymerization. Fluid drag reduction performance of hydrogel surface was measured using a rotational rheometer by the plate-plate mode. The experimental results showed that the average drag reduction of hydrogel surface could reach up to about 56% in Couette flow, which was mainly due to the interfacial polymerization phenomenon that enhanced the ability of hydration layer to delay the momentum dissipation between fluid layers and the diffusion behavior of surface. The proposed drag reduction mechanism of hydrogel surface was expected to shed new light on hydrogel-liquid interface interaction and provide a new way for the development of steady-state drag reduction methods.

Liquid Metal Nanocores Initiated Construction of Smart DNA-Polymer Microgels with Programmable and Regulable Functions and Near-Infrared Light-Driven Locomotion.

Due to their sequence-directed functions and excellent biocompatibility, smart DNA microgels have attracted considerable research interest, and the combination of DNA microgels with functional nanostructures can further expand their applications in biosensing and biomedicine. Gallium-based liquid metals (LMs) exhibiting both fluidic and metallic properties hold great promise for the development of smart soft materials; in particular, LM particles upon sonication can mediate radical-initiated polymerization reactions, thus allowing the combination of LMs and polymeric matrix to construct "soft-soft" materials. Herein, by forming active surfaces under sonication, LM nanoparticles (LM NPs) initiated localized radical polymerization reactions allow the combination of functional DNA units and different polymeric backbones to yield multifunctional core/shell microgels. The localized polymerization reaction allows fine control of the microgel compositions, and smart DNA microgels with tunable catalytic activities can be constructed. Moreover, due to the excellent photothermal effect of LM NPs, the resulting temperature gradient between microgels and surrounding solution upon NIR light irradiation can drive the oriented locomotion of the microgels, and remote control of the activity of these smart microgels can be achieved. These microgels may hold promise for various applications, such as the development of in vivo and in vitro biosensing and drug delivery systems.

Versatile synthesis of siloxane‐based graft copolymers with tunable grafting density

AbstractA versatile synthetic platform is reported that affords high molecular weight graft copolymers containing polydimethylsiloxane (PDMS) backbones and vinyl‐based polymer side chains with excellent control over molecular weight and grafting density. The synthetic approach leverages thiol‐ene click chemistry to attach an atom‐transfer radical polymerization (ATRP) initiator to a variety of commercially available poly(dimethylsiloxane‐co‐methylvinylsiloxane) backbones (PDMS‐co‐PVMS), followed by controlled radical polymerization with a wide scope of vinyl monomers. Selective degradation of the siloxane backbone with tetrabutylammonium fluoride confirmed the controlled nature of side‐chain growth via ATRP, yielding targeted side‐chain lengths for copolymers containing up to 50% grafting density and overall molecular weights in excess of 1 MDa. In addition, by using a mixture of thiols, grafting density and functionality can be further controlled by tuning initiator loading along the backbone. For example, solid‐state fluorescence of the graft copolymers was achieved by incorporating a thiol‐containing fluorophore along the siloxane backbone during the thiol‐ene click reaction. This simple synthetic platform provides facile control over the properties of a wide variety of grafted copolymers containing flexible PDMS backbones and vinyl polymer side chains.

Synthesis and applications of a Y‐inimer with two orthogonal controlled free radical polymerization initiators

AbstractWe report the synthesis of a Y‐shaped inimer that contains two orthogonal initiators for ATRP and NMP. The inimer is synthesized through a one‐pot multi‐component reaction that vastly simplifies the typically cumbersome synthesis of similar compounds. The Y‐inimer has the versatility to be homopolymerized into a backbone for A/B Janus bottlebrush synthesis or copolymerized with glycidyl methacrylate (GMA) and cross‐linked into an ultra‐thin coating for mixed A/B brush growth from planar surfaces. Importantly, the Y‐shaped nature of the inimer ensures growth of A and B brushes are consistently in a 1:1 ratio. We demonstrate the application of the Y‐inimer in the synthesis of a PMMA/PS Janus bottlebrush as well as two different mixed A/B polymer brushes, one with the ability to microphase separate, and a second mixed polyelectrolyte brush with opposite charges. The inimer is compatible with various A/B monomer systems and offers a universal approach to the “grafting‐from” polymerization of dual vinyl polymer side chains. This study provides a unique way of utilizing multi‐component reactions in polymer chemistry to access complex functional architectures.

New substituted pentazadienes as initiators of free-radical polymerization: synthesis, photochemical properties and perspectives for holographic media

The series of 4,4′-substituted 3-hydroxyethyl-pentaza-1,4-dienes were synthesized in the reaction of aromatic diazonium salts with an ethanol amine. Photolysis of pentaza-1,4-dienes was investigated by means of UV/Vis spectroscopy. Electron donating methyl and methoxy substituents were found to increase photosensitivity whereas electron withdrawing chloro-substituents cause higher photolytic stability. 3-hydroxyethyl-pentaza-1,4-dienes as a radical polymerization initiator has been successfully investigated in 10% methyl methacrylate solution in DMF. Gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) were used for obtained polymers characteristics evaluation. The highest values of PMMA Mn and Đ can be obtained in the case of chloro-substituted derivative. The holograms of a plane wavefront were recorded in media based on obtained PMMA doped by azo-dye by a 532 nm laser in a ∼1-μm-thick sample. The diffraction efficiency values for parallel polarized acting light increased in Cl→Me→OMe series.