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Butyl acrylate is polymerized in the living way under the irradiation of purple light-emitting diode (LED) or sunlight without photocatalyst at ambient temperature. 2-((Phenoxycarbonothioyl)thio) ethyl propanoate) is exclusively added and acted as an initiator and a chain transfer agent simultaneously in the current system. Poly(butyl acrylate) with well-regulated molecular weight and relatively narrow molecular weight distribution (Ð < 1.30) is synthesized. High conversion (>95%) can be achieved within several minutes. Polymerization shows oxygen tolerance. Near quantitative end-group fidelity of polymer is demonstrated by 1 H NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectra., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Photoinduced 3D printing based on the reversible addition‐fragmentation chain transfer (RAFT) process has emerged as a robust method for creating diverse functional materials. However, achieving precise control over the mechanical properties of these printed objects remains a critical challenge for practical application. Here, we demonstrated a RAFT step‐growth polymerization of a bifunctional xanthate and bifunctional vinyl acetate. Additionally, we demonstrated photoinduced 3D printing through RAFT step‐growth polymerization with a tetrafunctional xanthate and a bifunctional vinyl acetate. By adjusting the molar ratio of the components in the printing resins, we finely tuned the polymerization mechanism from step‐growth to chain‐growth. This adjustment resulted in a remarkable range of tunable Young's moduli, ranging from 7.6 MPa to 997.1 MPa. Moreover, post‐functionalization and polymer welding of the printed objects with varying mechanical properties opens up a promising way to produce tailor‐made materials with specific and tunable properties. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The application of reversible degenerative radical polymerization (RDRP) in the construction of polymer networks (PNs) provides a facile and convenient way to fabricate 3D objects with the ability to be posttransformed. However, the polymerization mechanism mainly relies on chain‐growth polymerization, which limits its wide application for various polymeric materials with different functionalities. Here, we present a method toward PNs by utilizing a photoinduced RAFT step‐growth polymerization, which is based on a RAFT single unit monomer insertion (SUMI) reaction between a xanthate and an alkyl vinyl group. Benefiting from this reaction, a pendant RAFT agent can be generated in each repeat unit of the backbone during the polymerization. These reactivatable dormant species can be further used for the postfunctionalization of PNs prepared by step‐growth polymerization of multifunctional monomers. Moreover, the prepared PNs are degradable owing to the introduction of ester groups, providing an avenue toward degradable and stimuli‐responsive materials. [ABSTRACT FROM AUTHOR]

Light‐regulated polymerization has emerged as a powerful tool to control the process of polymerization. However, tuning the polymer molecular weight distribution (MWD) by light is still not well developed. Here, we present a convenient approach for controlling the MWD in reversible addition‐fragmentation chain transfer (RAFT) polymerization by exploiting an ultraviolet light‐induced RAFT‐hetero‐Diels–Alder (RAFT‐HDA) reaction with a photoenol diene. The key point in this strategy is to terminate part of the propagating chains at a specific time by the RAFT‐HDA reaction. In addition, a photoenol diene with a hydroxyl group is also synthesized and successfully applied to realize this strategy, which can be further utilized for chain extension of ɛ‐caprolactone (ɛ‐CL) by ring opening polymerization to prepare diblock copolymers with different MWDs. [ABSTRACT FROM AUTHOR]

Selenium‐containing polymers have attracted considerable attention due to their unique redox responsiveness. Here, phenyl vinyl selenide (PVSe), as a functional selenium‐containing monomer, is polymerized with maleimide (MI) or its derivatives by reversible addition–fragmentation chain transfer polymerization. The resulting polymers are characterized by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopy and proton nuclear magnetic resonance spectra, which particularly prove the obtaining of alternating polymers through the polymerization of PVSe and MI or its derivatives. Properties of the resulting polymers are systematically investigated, such as glass transition temperature, thermal performance, and refractive indices. What's more, based on phenylseleno oxidation elimination, the alternating polymers are oxidized through 30% H2O2 to form precisely structured olefin copolymers with carboncarbon (CC) double bonds. The selective generation of double bonds in the alternating polymers is systematically studied. The efficiency of such oxidation is very high under mild conditions due to low electronegativity and bond energy of carbonselenium (CSe) bond, which provides a novel method to prepare precisely structured olefin copolymers with MI or its derivatives. [ABSTRACT FROM AUTHOR]

Selenium‐containing monomer (p‐phenylseleno) styrene (p‐PhSeSt) is polymerized by reversible addition‐fragmentation chain transfer polymerization. Polymer, (P(p‐PhSeSt)), with controlled molecular weight and narrow molecular weight is obtained. The selenide moiety in obtained P(p‐PhSeSt) can be selectively oxidized to selenoxide or selenone groups by H2O2 or NaClO, respectively. These oxidized groups can be further reduced to selenide by Na2S2O4. The structure changing of polymers during such redox cycle is characterized by nuclear magnetic resonance, X‐ray photoelectron spectroscopy, and size exclusion chromatography. Properties, such as thermal performance, glass transition temperature, water contact angles, and refractive indices, of the resulting polymers are systematically investigated before and after oxidation. In addition, SiO2 inverse opal photonic crystal (IOPC) is fabricated by sacrificial polymer colloidal template method. Owing to changes of the RIs of P(p‐PhSeSt) after selective oxidation, the predictable change of PC bandgap as a redox‐responsive PC sensor is successfully realized, which provides new perspectives for modulating photonic crystals. [ABSTRACT FROM AUTHOR]

Polymer molecular weight distribution (MWD) is a key parameter of polymers. Here we present a robust method for controlling polymer MWD in controlled cationic polymerizations. A latent mediator strategy was designed and combined with temporal programming to regenerate mediators at different times during polymerization. Both the breadths and shapes of MWD curves were tuned easily by adjusting an external light source. Bimodal, trimodal, and tetramodal distributions were obtained, and the breadths could be varied from 1.06 to 2.09. Polymers with different MWDs prepared by this method had good chain end fidelity, which was demonstrated with successful chain‐extension experiments. In addition, the introduction of temporal programming with a computer‐controlled single chip for the light source opened an avenue for the use of artificial intelligence in polymer synthesis. [ABSTRACT FROM AUTHOR]

Poly(glycidyl methacrylate) (PGMA) was synthesized by Fe(0)-mediated living radical polymerization followed with post-modification by PhSeZnCl. A series of selenide functionalized PGMAs with different selenium concentrations and molecular weights were obtained. The introduction of selenide groups into PGMA resulted in a polymer with high refractive index. The relationships between the concentration of selenium, degree of polymerization and refractive index were investigated. Results showed that the refractive index of the final polymer could be adjusted by the concentration of selenium and degree of polymerization, which provided a useful way to fabricate polymeric materials with adjustable refractive index. [ABSTRACT FROM AUTHOR]

Vinyl acetate is polymerized in the living way under the irradiation of blue light-emitting diodes (LEDs) or sunlight without photocatalyst at ambient temperature. 2-(Ethoxycarbonothioyl)sulfanyl propanoate is exclusively added and acts as initiator and chain transfer agent simultaneously in the current system. Poly(vinyl acetate) with well-regulated molecular weight and narrow molecular weight distribution (Ð < 1.30) is synthesized. Near quantitative end group fidelity of polymer is demonstrated by nuclear magnetic resonance (NMR) and matrix-assisteed laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). [ABSTRACT FROM AUTHOR]

A novel Janus compound containing azo-based thermal initiator and bromo-based atom transfer radical polymerization (ATRP) initiator group is synthesized. Such compound can be applied in the living radical polymerization of alkyl methacrylate monomers, such as methyl methacrylate, tert-butyl methacrylate, and 2-( N, N-dimethylamino) ethyl methacrylate. Polymers with controlled molecular weights and narrow molecular weight distributions are obtained. The structure of polymers is identified by 1H NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrum. A modified initiator for continuous activator regeneration ATRP mechanism is proposed according to the polymerization behavior, hydrolysis of chain backbone, and end group identification. [ABSTRACT FROM AUTHOR]

Diselenide-containing polymers are facilely synthesized from polymers prepared by atom transfer radical polymerization (ATRP). Benefiting from the ATRP technology, this protocol provides a flexible route for controlling the polymer structure, which allows for a great variety of architectures of selenium-containing polymer materials for applications in various fields. The oxidative and reductive responsive behavior of the obtained diselenide-containing polymers is also investigated. [ABSTRACT FROM AUTHOR]

An iron-mediated reverse ATRP of methyl methacrylate (MMA) is successfully carried out in water in the absence of any dispersants, using a water-soluble 2,2′-azobis(2-methylpropionamidine) dihydrochloride (V-50) as the initiator and the stabilizer, and using an oil-soluble N,N-butyldithiocarbamate ferrum (Fe(S2CN(C4H9)2)3) as the catalyst without adding any additional ligands. Micron-sized PMMA particles with UV light-sensitive -S2CN(C4H9)2 end group are obtained, and monomer droplet nucleation and suspension polymerization mechanism are proposed. Polymerization results demonstrated typical 'living'/controlled characteristics of ATRP: first-order polymerization kinetics, linear increase of molecular weights with monomer conversion and narrow molecular weight distributions for the resultant PMMA particles. NMR spectroscopy and chain-extension experiments under UV light irradiation confirm the attachment and livingness of UV light-sensitive -S2CN(C4H9)2 group in the chain end. [ABSTRACT FROM AUTHOR]

ABSTRACT The living free radical polymerizations of vinyl acetate (VAc) were successfully achieved in the presence of a novel organic selenium compound (diselenocarbonates), with 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The living characteristics of the VAc polymerization were confirmed by the linear first-order kinetic plots and linear increase of molecular weights ( Mn) of the polymers with monomer conversions, while keeping the relatively low molecular weight distributions. In addition, the end of the polymers contains selenium element which may be useful in biotechnological and biomedical applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3159-3165 [ABSTRACT FROM AUTHOR]

Hyperbranched polycaprolactone with controlled structure was synthesized by reversible addition-fragmentation chain transfer radical ring-opening polymerization along with self-condensed vinyl polymerization (SCVP) of 2-methylene-1,3-dioxepane (MDO). Vinyl 2-[(ethoxycarbonothioyl) sulfanyl] propanoate (ECTVP) was used as polymerizable chain transfer agent. Living polymerization behavior was proved via pseudo linear kinetics, the molecular weight of polymers increasing with conversion and successful chain extension. The structure of polymers was characterized by 1H NMR spectroscopy, tripe detection gel permeation chromatography, and differential scanning calorimetry. The polymer composition was shown to be able to tune to vary the amount of ester repeat units in the polymer backbone, and hence determine the degree of branching. As expected, the degree of crystallinity was lower and the rate of degradation was faster in cases of increasing the number of branches. [ABSTRACT FROM AUTHOR]