Copolymerization Of Methyl Methacrylate Research Articles

Triple passivation strategy for ultra-stable luminous CsPbBr3 NCs-Acrylate based films as backlight display

To improve the stability of CsPbBr3 nanocrystals (NCs), triple protection strategies were performed to obtain the ultra-stable films, including fluorinated hydrophobic film surface, polymer coating and silica encapsulation. CsPbBr3 QDs@SiO2 nanoparticles (SiPNCs) were prepared with well-dispersed NCs (8 nm) within acrylate-modified silica-shell. Polymer@SiPNCs (poly@SiPNCs) films were prepared by copolymerization of methyl methacrylate (MMA), 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl methacrylate (DFHM) and SiPNCs under ultraviolet (UV) light. Compared to CsPbBr3 NCs solution, SiPNCs solution had well maintained light absorption and emission wavelengths of ∼509 nm and ∼522 nm respectively. High SiPNCs content resulted in enhanced micro/nano structure and increased roughness on the surface of poly@SiPNCs film. With increasing SiPNCs content, water contact angles (WCAs) of poly@SiPNCs films reached 126 ± 2.4°, 137.3 ± 1.3° and 141.5 ± 1.9° respectively. This fabricated poly@SiPNCs film exhibited much improved stabilities to water and UV light, even after 90 days of water immersion and 120 h of UV irradiation. White light-emitting-diode (LED) device emitted bright pure white light. This work will boost a large-scale preparation of stable QDs films as backlight display.

Carbon microspheres/carbon sheets as efficient electromagnetic wave absorbers

To address the issue of weak absorption intensity and narrow frequency band in pure dielectric electromagnetic wave (EMW) absorbing materials, this study adopts a simple method to successfully prepare a pure dielectric EMW absorption material by modifying acrylonitrile–methylmethacrylate copolymer carbon microspheres (co-AN-MMA@CS) with capsaicin-like 3,5-dimethylphenol derivative (DMPD). The introduction of DMPD into the carbon microspheres increases the heteroatoms (N, O) in the carbon material, thus resulting in functional groups (-C-N, –NO, and C–O) that enable energy loss through dipole polarization. Additionally, the special morphology of carbon microspheres attached or embedded in carbon sheets derived from DMPD increases the inhomogeneous interfaces, thereby increasing the interface polarization relaxation and further attenuating EMWs. The resulting carbon material with the optimal structure (denoted as CNO-2) exhibits superior EMW absorption properties. At a thickness of 2.50 mm, the minimum reflection loss (RLmin) reaches −63.10 dB at 13.14 GHz, whereas the maximum effective absorption bandwidth (EABmax) reaches 6.81 GHz (8.95–15.76 GHz). CNO-2 has excellent EMW absorption capabilities due to the controllable complex dielectric constant and multiple attenuation mechanisms, including interfacial polarization, dipole polarization, and conduction loss. The CNO absorbers prepared in this study can be used as efficient microwave absorbers for electromagnetic protection applications.

Adaptable intelligent filters based on nanotextured nonwoven membranes containing water-insoluble hydrogels

The work demonstrates, for the first time, thermo-responsive, water-insoluble, hydrogel-based, nano-fibrous filter media comprised of copolymers of N-isopropylacrylamide (NIPAM) and methyl methacrylate formed by electrospinning. Moreover, a comprehensive novel physical explanation of all aspects responsible for the physical mechanisms resulting in the thermo-responsive regulation of the water flow rate and an enhanced interception of nanoparticles by such filter membranes is given. They are the wettable-non-wettable transition, pore, and fiber-size changes, as well as a diminishing filter thickness at the lower critical solution temperature (LCST) of the copolymers developed here, which interplay with a significant reduction in the water viscosity with temperature. Poly(N-isopropylacrylamide) (PNIPAM) hydrogel is an attractive material because of its thermo-responsive properties. Its wettability changes with water temperature. This characteristic holds great promise for the development of advanced filter media and related responsive materials. In this study, PNIPAM hydrogels were designed and transformed into filter membranes for applications in water filtration in biomedical and other related systems. These thermo-responsive filter membranes offer the potential for enhanced filtration efficiency, selectivity, and the overall system performance. Here, two different procedures were adopted to form water-insoluble thermo-responsive filter media based on PNIPAM hydrogels. The PNIPAM-based hydrogels were electrospun, resulting in the formation of thermo-responsive water-insoluble nanofiber membranes. These membranes underwent a series of comprehensive experiments to assess their performance and characteristics, including mass loss, water droplets for the wettability assessment, filtration tests, shrinkage measurements, and microscopic observations. These diverse experiments yield a full understanding of the PNIPAM-based nanofiber membranes’ properties and their potential applications.

Bulk Depolymerization of Methacrylate Polymers via Pendent Group Activation.

In this study, we present an efficient approach for the depolymerization of poly(methyl methacrylate) (PMMA) copolymers synthesized via conventional radical polymerization. By incorporating low mol % phthalimide ester-containing monomers during the polymerization process, colorless and transparent polymers closely resembling unfunctionalized PMMA are obtained, which can achieve >95% reversion to methyl methacrylate (MMA). Notably, our catalyst-free bulk depolymerization method exhibits exceptional efficiency, even for high-molecular-weight polymers, including ultrahigh-molecular-weight (106-107 g/mol) PMMA, where near-quantitative depolymerization is achieved. Moreover, this approach yields polymer byproducts of significantly lower molecular weight, distinguishing it from bulk depolymerization methods initiated from chain ends. Furthermore, we extend our investigation to polymethacrylate networks, demonstrating high extents of depolymerization. This innovative depolymerization strategy offers promising opportunities for the development of sustainable polymethacrylate materials, holding great potential for various applications in polymer science.

Charge transport mechanism and trap origin in methyl methacrylate copolymer with thioxanthenone side groups

The transverse charge transport mechanism in a specially synthesized novel methyl methacrylate copolymer containing 2 % electron-accepting 9H-thioxanthene-9-one side groups (poly(MMA-co-ThS)) has been studied experimentally and theoretically. These side groups are shown to be deep electron traps. The charge transport in poly(MMA-co-ThS) is governed by the model of phonon-assisted tunneling between traps. The optical ionization trap energy (Wopt = 1.8 eV), independently determined by a reduction spectroelectrochemical method, confirms the validity of the phonon-assisted tunneling model used to describe charge transport in organic dielectrics with high content of electron traps.

Enhanced flame retardancy and thermal stability in flexible polyurethane foam through synergistic core-shell structured DBDPE@PMA particles

This research presents the synthesis of core–shell structured flame retardant particles, DBDPE@PMA, which combines the flame-retardant and toughening functions. These particles utilize decabromodiphenyl ethane (DBDPE) as the core and a copolymer of methyl methacrylate and acrylic acid (MMA-AA) as the shell, which are created via emulsion polymerization. The process involved an initial reaction of DBDPE@PMA with isocyanate, followed by foaming with polyether polyol to fabricate flame retardant, and the flexible polyurethane foam (P/D-FPUF) was thermally insulated. The study examined the influence of DBDPE@PMA on the flame retardancy properties of flexible polyurethane foam. Scanning electron microscopy confirmed the encapsulation of DBDPE by the polymer, resulting in a core–shell composite particle. The interaction between the carboxylic groups (–COOH) on the DBDPE@PMA shell and isocyanate enhanced the interfacial bonding, thereby increasing the foam's apparent density and ensuring better integration with the polyurethane matrix. However, DBDPE@PMA had aggregates on the foam matrix bubble holes, resulting in uneven bubble holes. DBDPE@PMA markedly improved the flame retardancy and thermal stability of the foam, compared to both pure polyurethane and foam containing solely DBDPE (10D-FPUF). The oxygen index value of the foam with 20% DBDPE@PMA (20P/D-FPUF) reached 33.6%, with UL-94 horizontal and Vertical burning level tests achieving the highest classifications. The char residue after thermal degradation increased significantly from 1.93% in pure foam to 5.06%. While the smoke density level rose, the duration to peak smoke density was prolonged to 78 s, offering an enhanced margin for evacuation during the initial stages of a fire.

Preparation and Characterization of Chloroprene Latexes Modified with Vinyl-POSS.

Water-based chloroprene latex is a solvent-free, environmentally friendly adhesive. Currently, its market demand is growing rapidly. However, there are problems such as a lack of heat resistance and poor mechanical properties, which limit its application. The introduction of vinyl-POSS (OVS) into the resin structure can effectively improve the thermal stability of chloroprene adhesives. In this paper, modified waterborne chloroprene latex was prepared by copolymerization of methyl methacrylate and OVS with chloroprene latex. The results showed that vinyl-POSS was successfully grafted onto the main chain of the waterborne chloroprene latex, and the modified waterborne chloroprene latex had good storage stability. With the increase in vinyl-POSS, the tensile strength of the chloroprene latex firstly increased and then decreased, the tensile property (peel strength of 20.2 kgf) was maintained well at a high temperature (100 °C), and the thermal stability of the chloroprene latex was improved. When the addition amount was 4%, the comprehensive mechanical properties were their best. This study provides a new idea for the construction of a new and efficient waterborne chloroprene latex system and provides more fields for the practical application of waterborne chloroprene latex. This newly developed vinyl-POSS modified chloroprene latex has great application potential for use in home furniture, bags, and seat cushions.

Preparation of reed fibers reinforced graft-modified starch-based adhesives based on quantum mechanical simulation and molecular dynamics simulation

Starch is a biomass polymer material with a high yield and comprehensive source. It is used as a raw material for preparing adhesives because of its highly active hydroxyl group. However, poor adhesion and water resistance hinder the application of starch-based adhesives (SBAs). Based on this, the starch was modified through graft copolymerization with itaconic acid as a cross-linking agent, methyl methacrylate and methyl acrylate as copolymers. Additionally, reed fibers were synergistically modified with polydopamine deposition to prepare an environmentally friendly SBA used in plywood production. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H NMR), X-ray diffraction (XRD), and thermogravimetric analysis (TG) demonstrate that copolymerization of methyl methacrylate and methyl acrylate with starch improves the shear strength, water resistance, and thermal stability of the SBA. Compared to unmodified starch, the modified SBA exhibits a 129 % increase in dry strength and achieves a wet strength of 1.36 MPa. Fukui function, Frontier orbit theory, and molecular dynamics simulation have shown that itaconic acid promotes the copolymerization of starch and acrylate monomers. The modified starch has fewer hydrogen bonds, less order, and a denser macromolecular network structure, which provides a reference for studying the molecular interaction mechanisms of SBAs.

Fabrication of pH-Responsive Amphiphilic Poly(Vinyl Alcohol–Methyl Methacrylate) Copolymer Nanoparticles for Application in Cancer Drug Delivery Systems

Fabrication of pH-Responsive Amphiphilic Poly(Vinyl Alcohol–Methyl Methacrylate) Copolymer Nanoparticles for Application in Cancer Drug Delivery Systems

Printable Single‐Ion Polymer Nanoparticle Electrolytes for Lithium Batteries

New material solutions are searched for the manufacturing and safety of current batteries. Herein, an extrusion printable polymer separator for lithium batteries based on single‐ion polymer electrolytes is presented. The polymer electrolytes are based on methacrylic polymeric nanoparticles (NPs) functionalized with a lithium sulfonamide group combined with different organic plasticizers such as sulfolane and carbonates. The synthesis of the polymer NPs is carried out by emulsion copolymerization of methyl methacrylate and lithium sulfonamide methacrylate in the presence of a crosslinker, resulting in particle sizes of less than 30 nm, as shown by electron microscopy. Then polymer electrolytes are prepared by mixing polymer NPs with varying lithium sulfonamide content and different plasticizers such as carbonates and sulfolane. The polymer electrolytes show ionic conductivities between 2.9 × 10−4 and 2.3 × 10−5 S cm−1 at 85 °C with the highest values for the small‐sized NPs with the highest lithium content. As a proof‐of‐concept application, layer‐by‐layer printing of a sulfolane‐based polymer electrolyte is evaluated via direct ink writing directly onto classic battery electrodes. The electrochemical characterization of the printed solid electrolyte indicates favorable properties, ionic conductivity, lithium transfer number, electrochemical stability window, and cyclability in lithium symmetrical cells, to be used in lithium batteries.

2D ZIF-L(Zn) for Hybrid Copolymerization of Methyl Methacrylate and ε-Caprolactone under Solvent-free Medium

Herein, we report the hybrid copolymerization of methyl methacrylate (MMA) and ε-caprolactone (CL). 2D metal-organic frameworks, ZIF-L as a robust polymerization catalyst, can catalyze this hybrid copolymerization. Though these monomers differ from each other in structure and activity, different characterization techniques (1H-NMR, 13C-NMR, GPC, DSC, fractional precipitation techniques) confirm that they form biodegradable block copolymer PMMA-b-PCL with high molecular weight (1190 kg/mol). Also, PXRD and SEM results of the recovered ZIF-L reveal that the catalyst ZIF-L is remarkably stable even after a long-time polymerization reaction with no significant loss in activity.

PH-Sensitive Acrylic Terpolymers for the Coating of Orally Administered Drugs Used for Colonic Release.

Polymeric coatings are a promising option for the development of delivery systems for orally administered drugs. However, the gastrointestinal conditions to which they are subjected, which include low pH and solubility as well as peristaltic movements, can limit their applications. In this work, different formulations of polymeric coatings were produced using pH-sensitive materials consisting of copolymers of methyl acrylate, methyl methacrylate, and methacrylic acid. The polymers were synthesized by the emulsion polymerization technique, obtaining small average particle sizes (56-190 nm), molecular weights between 200,000 and 400,000 g/mol, and a glass transition temperature above 35 °C, which are suitable for film formation at room temperature. Thus, they were assessed as coatings for hydroxypropyl methylcellulose capsules (HPMC) using the immersion method, showing adequate capacity to protect the capsule at gastric pH (pH 1.2) and dissolve at the simulated intestinal pH (pH= 7.2). In particular, the higher the content of the acidic monomer, the higher the release time of the test molecule contained in the acrylic terpolymer-coated HPMC capsules proposed, which was a curcuminoid derivative due to their bright color and potential medical benefits. In addition, a minimum number of immersions was required for coating the HPMC capsules at high acidic concentrations, which further facilitates the delayed release needed for colonic treatment. However, too high proportions of methacrylic acid may result in cytotoxicity issues. Consequently, a biocompatible formulation containing a proportion of methyl acrylate, methyl methacrylate, and methacrylic acid of 7:3:3 is proposed as the most adequate for colonic release. Thus, by chemically modulating the molar percentages of the acrylic monomers, it was possible to obtain tailored acrylic terpolymer coatings with different characteristics and desired properties in order to modulate the release kinetics of an active substance in a colonic environment.

Synthesis and characterization of PMMA-grafted-ZrO2 hybrid nanoparticles

In this study, we reported a facile synthesis and the characterization of PMMA-grafted ZrO2 hybrid nanoparticles from original ZrO2 (oZrO2) nanoparticles. The synthesis process included of three steps: (i) modification of nano ZrO2 with a vinyl silane agent, (ii) graft copolymerization of methyl methacrylate (MMA) monomers and modified ZrO2 (mZrO2) nanoparticles, and (iii) extraction of homo PMMA to obtain the final product of PMMA-g-ZrO2 (gZrO2) nanoparticles. Fourier transform infrared (FTIR) spectra and thermogravimetric analysis (TGA) of mZrO2, oZrO2, and gZrO2 indicated that the silane coupling agent was grafted onto oZrO2 nanoparticles. FTIR spectra of gZrO2 indicated PMMA had been successfully grafted onto the surface of ZrO2 nanoparticles. Using TGA method, the PMMA grafting content onto ZrO2 nanoparticles was evaluated as 9.03 wt.%. The electron microscopy (SEM) images of gZrO2, mZrO2, and oZrO2 indicated that their primary particle size and shape were almost unchanged after modification processes, their particle size was in the range from 50 nm to 140 nm. XRD analysis showed the monoclinic crystalline structure of three kinds of ZrO2 nanoparticles (nanocrystals). The organic gZrO2 nanoparticles can be a better candidate as an opacifier additive for polymer nanocomposites or acrylic bone cement.

A stable metal ferrite Construction, physical Characterizations, and investigation magnetic properties in thin polymer films

A stable nickel ferrite (NiFe2O4) was constructed as incorporated into starch grafted acrylic acid copolymer matrix by co-precipitations followed by annealing. A sample, as annealed at temperature 600 °C, yields a NiFe2O4 of tailored the magnetic properties. The structural, morphological and magnetic properties were investigated by XRD, FTIR, SEM and VSM characterizations. SEM and XRD analysis indicate that particle size in the nano range. In-situ polymerization process was used to insert prepared material with acceptable surface morphology into a starch-grafted methyl methacrylate copolymer. By using FTIR and VSM to assess the magnetic characteristics, nanocomposite was created in this manner was evaluated. Magnetic properties of (NiFe2O4) arise with saturation magnetization Ms = 19 emµg−1. Studies made at room temperature reveals the soft nature of synthesized ferrites. These approaches outcomes demonstrated the material value as a biodegradable thin film with tunable magnetic characteristics that may be used as magnetic strips in future.

Attapulgite and Graphene‐Based Molecular Imprinted Polymers as 5‐FU Delivery Systems for the Treatment of Cervical Cancer**

AbstractMolecularly imprinted polymers and non‐imprinted polymers based on attapulgite and graphene composite were synthesized by coating with copolymer of acrylamide and methyl methacrylate. The adsorption results showed that the molecularly imprinted polymers and non‐imprinted polymers could reach the maximum drug loading of 2.4 and 1.6 mg/g, respectively. The in vitro release studies demonstrated that molecularly imprinted polymers and non‐imprinted polymers can control the release of 5‐fluorouracil and reach maximum release at approximately 48 h. Cytotoxicity analysis showed that 100 μg/mL of molecularly imprinted polymers loaded with 5‐fluorouracil gradually increased the inhibition rate of HeLa with increasing time and approached the maximum inhibition rate of 20 % at 72 h.

Chameleon-like Photoluminescent Janus Nanoparticles as Full-Color Multicomponent Organic Nanoinks: Combination of Förster Resonance Energy Transfer and Photochromism for Encryption and Anticounterfeiting with Multilevel Authentication.

Increasing the security by the multilevel authentication mechanism was the most significant challenge in recent years for the development of anticounterfeiting inks based on photoluminescent nanomaterials. For this purpose, the greatest strategy is the use of multicomponent organic materials and a combination of Förster resonance energy transfer (FRET) with the intelligent behavior of photochromic compounds like spiropyran. Here, the hydroxyl-functionalized polymer nanoparticles were synthesized by emulsion copolymerization of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) in different compositions (0-30 wt % of HEMA). Results illustrated that the size of the nanoparticles changed from 64 to 204 nm, and a morphology evolution from spherical to Janus shape was observed by increasing the concentration of HEMA. Photoluminescent inks with red, green, and blue (RGB) fluorescence emissions were prepared by modification of nanoparticles containing 15 wt % of HEMA with spiropyran, fluorescein, and coumarin, respectively. To develop dual-color and multicolor photoluminescent inks that display static and dynamic emission, RGB latex samples were mixed together in different ratios and printed on cellulosic paper. Results display that the fluorescence emission of developed inks can be photoswitched between different statuses, including white to blue, green to blue, green to red/orange, purple to pink, and white to pink, utilizing the FRET phenomenon, photochromism, and a combination of both phenomena. Samples containing spiropyran displayed dynamic color changes in the emission to red, orange, and pink depending on the composition. Hence, developed dual-color and multicolor photoluminescent inks were used for printing of security tags and also painting of some hand-drawn artworks, which obtained results indicating high printability, maximum fluorescence intensity, high resolution, and fast responsivity upon UV-light irradiations of 254 nm (for static mode) and 365 nm (for dynamic mode). In addition, the multilevel authentication mechanism by a static emission under UV-light irradiation of 254 nm, a dynamic emission under UV-light irradiation of 365 nm, and photochromic color change was observed, resulting in increasing the security of developed inks. Actually, developed multicolor photoluminescent inks are the most efficient candidates for developing a new category of chameleon-like high-security anticounterfeiting inks that have tunable optical properties and complex multilevel authentication mechanisms.

Poly(methyl methacrylate‐co‐butyl acrylate) copolymer/Ag nanocomposites prepared by latex mixing for multifunctional coatings

AbstractInspired by mussel chemistry, we presented a facile and eco‐friendly method to synthesize silver nanoparticles (AgNPs) using dopamine as a reductant and stabilizer. The synthesized AgNPs as an antibacterial agent and photothermal filler were further introduced to random copolymers of methyl methacrylate and butyl acrylate (MMA‐co‐BA) via latex mixing. The morphology and structure of the formed AgNPs were confirmed by transmission electron microscopy (TEM), UV–Vis spectrum, and x‐ray powder diffraction (XRD). The results showed that the synthesized AgNPs were spherical in the size of 5–30 nm with the characteristic crystalline structure of AgNPs. Mechanical properties of MMA‐co‐BA were significantly enhanced by the introduction of AgNPs. The MMA‐co‐BA/Ag nanocomposite films showed antibacterial activity against E. coli and S. aureus. Moreover, the scratches on the MMA‐co‐BA/Ag nanocomposite film can be healed under infrared light irradiation, which indicated that AgNPs enhanced the self‐healing ability of the MMA‐co‐BA. This work offers a viable avenue for developing antibacterial activity and self‐healing multifunctional coatings.Highlights Silver nanoparticles modified by dopamine are introduced to acrylic copolymer. Acrylic copolymer/Ag nanocomposites exhibit antibacterial activity. Acrylic copolymer/Ag nanocomposites have photothermal performance. Acrylic copolymer/Ag nanocomposites have self‐healing ability.

Capturing Acidic CO2 Using Surface-Active Difunctional Core-Shell Composite Polymer Particles via an Aqueous Medium.

Multifunctional surface-active polymeric composites are attractive materials for the adsorption of various small molecules. Herein, dual-functionalized micron-sized surface-active composite polymer particles were prepared by a three-step process for CO2 adsorption. First, polystyrene (PS) seed particles were prepared via the dispersion polymerization of styrene. PS/P(MMA-AAm-EGDMA) composite polymer particles were then synthesized by aqueous seeded copolymerization of methyl methacrylate (MMA) and acrylamide (AAm) in the presence of an ethylene glycol dimethacrylate (EGDMA) cross-linker. Finally, the amide moieties of PS/P(MMA-AAm-EGDMA) composite particles were converted into an amine-functionalized composite by using the Hofmann degradation reaction. The presence of primary amine groups on the surface of aminated composite particles was confirmed by some conventional chemical routes, such as diazotization and Schiff's base formation reactions. The formation and functionality of the PS seed, PS/P(MMA-AAm-EGDMA), and aminated PS/P(MMA-AAm-EGDMA) composite polymer particles were confirmed by Fourier transform infrared (FTIR) spectra analyses. Scanning electron microscopy (SEM) analysis revealed spherical shape, size, and surface morphologies of the PS seed, reference composite, and aminated composites. The elemental surface compositions, surface porosity, pore volume, pore diameter, and surface area of both composite particles were evaluated by energy-dispersive X-ray (EDX) mapping, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses. Dynamic light scattering (DLS) and ζ-potential measurements confirmed the pH-dependent surface properties of the functionalized particles. The amount of the adsorbed anionic emulsifier, sodium dodecyl sulfate (SDS), on the surface of aminated PS/P(MMA-AAm-EGDMA) is higher at pH 4 than that at pH 10. A vice versa result was found in the case of cationic surfactant, hexadecyltrimethylammonium bromide (HTABr), adsorption. Synthesized aminated composite particles were used as an adsorbent for CO2 adsorption via bubbling CO2 in an aqueous medium. The changes in dispersion pH were monitored continuously during the adsorption of CO2 under various conditions. The amount of CO2 adsorption by aminated composite particles was found to be 209 mg/g, which is almost double that of reference composite particles.

Cationic β‐Scission of C−H and C−C Bonds for Selective Dimerization and Subsequent Sulfur‐Free RAFT Polymerization of α‐Methylstyrene and Isobutylene

AbstractA series of exo‐olefin compounds ((CH3)2C(PhY)−CH2C(=CH2)PhY) were prepared by selective cationic dimerization of α‐methylstyrene (αMS) derivatives (CH2=C(CH3)PhY) with p‐toluenesulfonic acid (TsOH) via β‐C−H scission. They were subsequently used as reversible chain transfer agents for sulfur‐free cationic RAFT polymerization of αMS via β‐C−C scission in the presence of Lewis acid catalysts such as SnCl4. In particular, exo‐olefin compounds with electron‐donating substituents, such as a 4‐MeO group (Y) on the aromatic ring, worked as efficient cationic RAFT agents for αMS to produce poly(αMS) with controlled molecular weights and exo‐olefin terminals. Other exo‐olefin compounds (R−CH2C(=CH2)(4‐MeOPh)) with various R groups were prepared by different methods to examine the effects of R groups on the cationic RAFT polymerization. A sulfur‐free cationic RAFT polymerization also proceeded for isobutylene (IB) with the exo‐olefin αMS dimer ((CH3)2C(Ph)−CH2C(=CH2)Ph). Furthermore, telechelic poly(IB) with exo‐olefins at both terminals was obtained with a bifunctional RAFT agent containing two exo‐olefins. Finally, block copolymers of αMS and methyl methacrylate (MMA) were prepared via mechanistic transformation from cationic to radical RAFT polymerization using exo‐olefin terminals containing 4‐MeOPh groups as common sulfur‐free RAFT groups for both cationic and radical polymerizations.

Cationic β-Scission of C-H and C--C Bonds for Selective Dimerization and Subsequent Sulfur-Free RAFT Polymerization of α-Methylstyrene and Isobutylene.

A series of exo-olefin compounds ((CH3)2C(PhY)-CH2C(=CH2)PhY) were prepared by selective cationic dimerization of α-methylstyrene (αMS) derivatives (CH2=C(CH3)PhY) with p-toluenesulfonic acid (TsOH) via β-C-H scision. They were subsequently used as reversible chain transfer agents for sulfur-free cationic RAFT polymerization of αMS via β-C-C scission in the presence of Lewis acid catalysts such as SnCl4. In particular, exo-olefin compounds with electron-donating substituents, such as a 4-MeO group (Y) on the aromatic ring, worked as efficient cationic RAFT agents for αMS to produce poly(αMS) with controlled molecular weights and exo-olefin terminals. Other exo-olefin compounds (R-CH2C(=CH2)(4-MeOPh)) with various R groups were prepared by different methods to examine the effects of R groups on the cationic RAFT polymerization. A sulfur-free cationic RAFT polymerization also proceeded for isobutylene (IB) with the exo-olefin αMS dimer ((CH3)2C(Ph)-CH2C(=CH2)Ph). Furthermore, telechelic poly(IB) with exo-olefins at both terminals was obtained with a bifunctional RAFT agent containing two exo-olefins. Finally, block copolymers of αMS and MMA were prepared via mechanistic transformation from cationic to radical RAFT polymerization using exo-olefin terminals containing 4-MeOPh groups as common sulfur-free RAFT groups for both cationic and radical polymerizations.