Polymerization Of Vinyl Monomers Research Articles

Development of Ring-Expansion RAFT Polymerization of tert-Butyl Acrylate with a Cyclic Trithiocarbonate Derivative toward the Facile Synthesis of Cyclic Polymers.

Polymers with cyclic topology have no terminal structure and, therefore, exhibit various unique physical and functional properties compared to those of linear analogs. In this paper, we report an innovative methodology for the synthesis of cyclic polymers via ring-expansion RAFT (RE-RAFT) polymerization of vinyl monomers using a cyclic trithiocarbonate derivative (CTTC) as a RAFT agent. RE-RAFT of tert-butyl acrylate (TBA) was performed to yield a mixture of polymers exhibiting a bimodal size exclusion chromatography (SEC) trace. Both the peak top molecular weights shifted to higher-molecular-weight regions as the monomer conversion increased. The structure of the resulting polymer mixture was examined by 1H NMR and MALDI-TOF-MS. Detailed studies indicated that the obtained polymer of higher molecular weight was one of the large-sized cyclic polymers generated by the fusion of smaller-sized cyclic polymers during the RE-RAFT polymerization process. This approach opens the door to the simple synthesis of well-controlled cyclic polymers with complex structures, such as alternating and multi-block repeat unit sequences.

Lignin‐Alkali Metal Ion Self‐Catalytic System Initiated Rapid Polymerization of Hydrogel Electrolyte with High Strength and Anti‐Freezing Ability

AbstractHydrogel electrolyte is not resistant to freezing and has weak mechanical properties, and its fabrication is time‐consuming and energy‐consuming, limiting its application. Here, a simple, universal, and fast gelation based on dealkaline lignin (DL) ‐alkali metal ions is developed. The complex formed by catechol and alkali metal ions promotes the equilibrium of redox reactions. The produced SO4−·, OH· and singlet oxygen (1O2) radicals are responsible for the rapid polymerization of vinyl monomers. Alkali metal ions play a dual role in the rapid polymerization and frost resistance of hydrogel electrolytes. By modulating the mass ratio of DL and metal ion concentration, the preferred hydrogel electrolyte can be fabricated in an alkaline aqueous solution for 4 min at room temperature and possesses excellent anti‐freezing performance (0.51 mS cm−1 at −40 °C) and strong mechanical properties (tensile stress: 0.4 MPa, strain: 1125%). The hydrogel electrolyte‐assembled supercapacitor exhibits high stability at low temperatures. The specific capacitance retention is 89.7 % and 88.7 % after 5000 charge/discharge cycles at 25 and −20 °C, respectively. The lignin‐alkali metal ions self‐catalytic system completely different from the reported lignin‐oxidizing metal ion system will open up a new way for the fabrication of anti‐freezing ionic conductors and energy storage devices.

Metal-free ATRP with oligopyrene as a photocatalyst under LED irradiation

A metal-free approach to visible-light LED-induced atom transfer radical polymerization (ATRP) using oligopyrene as a photocatalyst is reported. The method facilitates the polymerization of various vinyl monomers, yielding polymers with molecular weight distribution as low as 1.32 and controlled chain-end functionality. Light on/off experiments demonstrate the light-dependent nature of the polymerization, confirming the effectiveness of the oligopyrene/alkyl halide system. The presented strategy paves the way for future advancements in polymer science, offering a metal-free alternative for controlled polymerization under visible light irradiation.

The Triumph of the Spin Chemistry of Fullerene C60 in the Light of Its Free Radical Copolymerization with Vinyl Monomers.

The spin theory of fullerenes is taken as a basis concept to virtually exhibit a peculiar role of C60 fullerene in the free radical polymerization of vinyl monomers. Virtual reaction solutions are filled with the initial ingredients (monomers, free radicals, and C60 fullerene) as well as with the final products of a set of elementary reactions, which occurred in the course of the polymerization. The above objects, converted to the rank of digital twins, are considered simultaneously under the same conditions and at the same level of the theory. In terms of the polymerization passports of the reaction solutions, a complete virtual picture of the processes considered is presented.

Acid-triggered radical polymerization of vinyl monomers

Reversible addition–fragmentation chain-transfer (RAFT) polymerization is one of the most versatile and robust controlled radical polymerization methods owing to its broad material scope and high tolerance to various functionalities and impurities. However, to operate RAFT polymerization, a constant supply of radicals is required, typically via exogenous thermal radical initiators that are not only challenging to transport and store, but also primarily responsible for termination and end-group heterogeneity. Here we present an acid-triggered RAFT polymerization that operates in the dark and without any conventional radical initiator. Abundant acids (for example, sulfuric acid) are shown to have a dual role initiating and accelerating the polymerization. The polymers prepared have low dispersity and high end-group fidelity. The method is compatible with a wide range of vinyl monomers and solvents, and can be applied to the synthesis of well-controlled high molecular weight block copolymers, as well as to free radical polymerization.

Facile synthesis of cyclic RAFT agents and ring expansion radical polymerization of vinyl monomers having cyclic topology

We describe the synthesis of cyclic vinyl polymers by ring-expansion radical polymerization using a cyclic RAFT agent, which is prepared by bimolecular ring-closing esterification of succinic acid and bis{4-[ethyl-(2-hydroxyethyl)carbamoyl]benzyl} trithiocarbonate.

(Invited) Lithium Battery Interfacial Engineering with Thin Conformal Polymer Coatings

Coupled chemical and mechanical phenomena at electrode interfaces largely govern the reversibility and long term stability of lithium ion and lithium metal batteries. A well-known example in lithium ion batteries is the formation of the electrically insulating, ionically conductive, continuous solid electrolyte interface (SEI) on graphitic anodes, which passivates the electrode against further electrochemical reduction of the electrolyte. Unfortunately, this stable passivation does not occur in Si and Li metal anodes. High voltage cathodes are also prone to detrimental interfacial processes, resulting in electrolyte oxidation, gas formation, and transition metal dissolution. In response, a myriad of coating technologies has been developed to mitigate and control these interfacial phenomena and enable next-generation electrodes. These technologies must provide thin, conformal coatings over the entire electrochemically active surface area of the electrode; the coatings must also possess the requisite mechanical properties to accommodate volume dilation due to lithium insertion/extraction.This presentation will describe the development of conformal, compliant polymer thin film coatings for lithium battery electrodes. The polymer thin films are prepared by initiated chemical vapor deposition (iCVD), which provides exquisite control over film composition and morphology by facilitating heterogeneous free-radical polymerization of vinyl monomers with thickness precision on the order of 1 nm. Poly(1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane) (pV4D4) was deposited onto silicon thin film electrodes using iCVD. 25 nm-thick pV4D4 films on Si electrodes improved initial coulombic efficiency by 12.9% and capacity retention over 100 cycles by 64.9% relative to untreated electrodes. PV4D4 coatings also improved rate capabilities, enabling higher lithiation capacity at all current densities. Post-cycling FTIR and XPS showed that pV4D4 inhibited electrolyte reduction and altered the SEI composition, with enrichment in LiF. In another example, thin conformal coatings of perfluorinated polymer were deposited onto battery-grade Cu current collectors to function as an artificial solid electrolyte interface. The effect of the film thickness on Li cycling reversibility was characterized. By galvanostatically cycling Li in an asymmetric Li||Cu cell using 1M LiFSI in a 1:1 (v/v) mixture of dioxolane:dimethoxyethane at 30°C, it was shown that the average coulombic efficiency averaged over 50 cycles increased from 98.36% for bare, untreated Cu to 99.08% for Cu coated with 25 nm of the fluoropolymer. Moreover, the 25 nm coating suppressed interfacial impedance growth on the current collector; the resistance of the coated Cu was 40% lower than the untreated Cu after 100 cycles. The mechanism by which the polymer coating enhances coulombic efficiency and suppresses side reactions will be discussed, along with discussion of the performance in practical anode-free lithium metal batteries.

Free radical (Co)Polymerization of aromatic vinyl monomers derived from vanillin

Chemical structure (effect of functional substituents on vinyl bond reactivity) was used as a criterion to evaluate the (co)polymerization behavior of vanillin-derived 3-allyl-5-vinylveratrole, 4-vinylveratrole, and 2-glycidoxy-5-vinylanisole in chain-growth polymerization mechanism. After polymerization, allyl and epoxy functional groups of monomer units remain unaffected as macromolecular side groups and can be utilized in post-polymerization reactions (in particular, cross-linking). Due to the intermolecular chain transfer to polymer, a fraction of branched macromolecules can be formed in free radical polymerization of 3-allyl-5-vinylveratrole. At the same time, the kinetic study shows a similar polymerization rate for all the three investigated biobased aromatic vinyl monomers.Determined in copolymerization with methyl methacrylate Q-e values indicate that 3-allyl-5-vinylveratrole, 4-vinylveratrole and 2-glycidoxy-5-vinylanisole behave like conventional vinyl monomers and can be copolymerized interchangeably. In this manner, macromolecules with controlled amounts of cross-linkable epoxy and allyl groups incorporated into the backbone can be synthesized. Based on the glass transition temperature of the homopolymers thereof (66–93 °C), biobased aromatic vinyl monomers can serve as “rigid” macromolecular fragments and be applied in the formulation of thermoset polymer coatings. Being derived from renewable resources, 3-allyl-5-vinylveratrole, 4-vinylveratrole, and 2-glycidoxy-5-vinylanisole can be considered as a replacement for petroleum-based commodity styrene in the production of various industrial polymeric materials that utilize aromatic monomers.

Living anionic polymerization of vinyl monomers using benzyltrimethylsilane‐metal alkoxide initiator systems

AbstractWell controlled living anionic polymerization of vinyl monomers was achieved by using the initiator system composed of desilylation of benzyltrimethylsilane (BnTMS) by potassium tert‐butoxide (t‐BuOK) in tetrahydrofuran and trapping the resulting benzyl anion with α‐methylstyrene or 1,1‐diphenylethylene in the initiator system in order to control the desilylation and polymerization reaction. This method led to high initiation efficiency and strict control of molecular weights of the obtained polymers. Furthermore, the initiator system could be applied to the synthesis of a block copolymer of PMMA‐b‐PtBMA. These results showed that living nature of the polymer obtained using BnTMS/t‐BuOK initiator system in the presence of the appropriate additives.

One‐Step Polymerizations Enable Facile Construction and Structural Optimization of Graft Copolymer Electrolytes

AbstractThe development of poly(ethylene oxide) (PEO)‐based solid polymer electrolytes (SPEs) is limited by the semi‐crystalline nature of PEO and the extremely strong EO‐Li+ interactions. To promote the rapid migration of Li+, a one‐step method combining radical polymerization and ring‐opening polymerization catalyzed simultaneously by lithium carboxylate is proposed to construct multi‐component graft copolymer electrolytes (GCPEs) in this study. Tailored macroinitiator with catalytic and initiated sites (PAALi(OH‐Br)) realizes one‐step polymerizations of vinyl monomers and cyclic monomers, and provides GCPEs with poly(ethylene glycol) (PEG) and poly(ε‐caprolactone) (PCL) side chains. The grafted structure of GCPE greatly facilitates the intra‐chain hopping of Li+, resulting in excellent ionic conductivity. The introduction of PCL further improves the tLi+ of GCPE. The three‐component graft copolymer electrolyte constructed by polystyrene (PS), PEO, and PCL exhibits high tensile stress (1.62 MPa), a high ionic conductivity (2.4 × 10−5 S cm−1, 30 °C), and a high tLi+ of 0.47 and high electrochemical stability.

Efficient continuous-flow synthesis of diacyl peroxide in a microreactor and the post-processing of its effluent

Di-(3,5,5-trimethylhexanoyl) peroxide (TMHP) is a low-temperature diacyl peroxide in liquid form, which is widely used as an initiator for the polymerization of vinyl monomers, especially for the production of polyvinyl chloride by suspension polymerization. However, the high reaction heat and the extreme instability of the product of the peroxidation reaction to synthesize TMHP often lead to safety concerns, therefore, the batch reaction processes often sacrifice efficiency in return for better safety. In this work, continuous-flow microreaction technology is utilized to realize an efficient and safe synthesis of TMHP. Under the conditions of T2 = 30°C, NaOH eq. = 1.05, and H2O2 eq. = 1.20, 94% yield could be obtained within 2.80 min, while batch reactors require hours to perform the same yield. It proves that, compared with batch processes, the efficiency is significantly improved by microreaction technology. Besides, a post-processing method for microreactor effluent is also proposed. After four post-processing steps of aging, washing, drying, and formulation, commercial TMHP product could finally be obtained. This work first reports the efficient and safe synthesis of TMHP based on microreaction technology and a post-processing method for microreactor effluent, which not only develops an efficient route from raw material to TMHP commercial products but also provides a basis for the process development of synthesizing other similar organic peroxides in a more efficient and safer manner.

Virtual Free-Radical Polymerization of Vinyl Monomers in View of Digital Twins.

The first case of virtual polymerization based on the concept of digital twins (DTs) is presented. The free-radical polymerization of vinyl monomers is considered to be a chain reaction consisting of a set of elementary ones. Those three types, related to the polymerization initiation and propagation as well as to the termination of polymer chain growth, are discussed. Special sets of DTs, whose total number approaches 60, distinguish each reaction type. The calculations are carried out using a semi-empirical version of the unrestricted Hartree-Fock approximation. The main energy and spin-density parameters of the ground state of the DTs are determined. The barrier profiles of two pairs of DTs are calculated, based on which two Evans-Polanyi-Semenov relations, attributed to elementary reactions of type (1) and (2), are constructed. These provide a quite reliable evaluation of the activation energy for the initiation and propagation of the free-radical polymerization of vinyl monomers in all the cases. The decisive role of spins in the formation of the elementary reaction transition states is established.

Cellulose nanocrystal/polymer nanocomposite latex via surfactant-free emulsion polymerization

Polar cellulose nanocrystals (CNCs) are difficult to disperse well in hydrophobic polymer matrices, and usually surfactants or expensive and time-consuming functionalization of the reinforcement or matrix have been attempted to improve dispersion. Here, we report a new, facile method to prepare CNC/polymer nanocomposite latices directly via surfactant-free emulsion polymerization of vinyl monomers and CNCs initiated by a cationic, water-soluble, free-radical initiator. The distribution of CNCs in the latex particles can be tailored through controlling the reaction procedures, namely, whether the monomers are added before or after preheating the CNCs with the initiator and has been confirmed by scanning electron microscopy (SEM) and scanning transmission X-ray microscopy (STXM) studies. CNCs distribute inside the latex particles if the monomers are added after the preheating step, and owing to the more even distribution of CNCs, such nanocomposite latices exhibit better mechanical properties than those prepared without preheating or via physically mixing CNCs with emulsions polymerized using conventional surfactant system. A latex particle formation mechanism is proposed based on these phenomena and polymerization kinetics studied in this work. Unlike typical CNC-based Pickering emulsion polymerization, our process can be operated without the need for intense mechanical shearing and provide an industrially scalable approach to prepare stable CNC/polymer nanocomposite latices that can be melt processed or used directly in a variety of applications, such as paints and coatings, adhesives, or cosmetics.

Toughening of alicyclic epoxy resin by in situ polymerization of modifier vinyl monomers using alkylborane as a radical initiator

AbstractIn this study, we attempted to improve the toughness of alicyclic epoxy cured resin using a vinyl polymer as a modifier which was generated with alkylborane as a radical initiator in parallel with the curing of the resin. Alkylborane has the ability to initiate radical polymerization around room temperature in the presence of oxygen, and the use of diethylmethoxyborane (DEMB) instead of a conventional peroxide radical initiator (DBPC) was found to allow copolymerization of styrene (St) and N‐phenylmaleimide (NPMI) in an alicyclic epoxy resin in the early stage of the multistep curing. As a result, only when DEMB was used as an initiator, a cured product with a phase‐separated structure at which ca. 50–100 nm St/NPMI copolymer phases were dispersed was obtained. The fracture toughness (KIC) of the modified cured resin with DEMB was 0.77 MN/m3/2, which was 30% higher than that of the modified resin with DBPC. Furthermore, the glass transition temperature of the modified cured resin with DEMB reached 247°C, which was 87 and 63°C higher than the unmodified rein and the modified resin with DBPC, respectively, since DEMB acted as a Lewis acid to promote cationic polymerization of the alicyclic epoxy resin.

New Approaches to the Synthesis and Stabilization of Polymer Microspheres with a Narrow Size Distribution.

This article presents the results of investigations on heterophase polymerization of vinyl monomers in the presence of organosilicon compounds of different structures. On the basis of the detailed study of the kinetic and topochemical regularities of the heterophase polymerization of vinyl monomers, the conditions for the synthesis of polymer suspensions with a narrow particle-size distribution using a one-step method have been determined.

Benzylsilane-metal alkoxide initiator systems for anionic polymerization of vinyl monomers

Benzylsilane-metal alkoxide initiator systems for anionic polymerization of vinyl monomers

From Glow to Growth: Chemiluminescence Induced Cationic Polymerization Using Ferrocenium Salt

AbstractChemiluminescence (CL) has recently emerged as a novel light source for triggering various photoreactions with appealing features such as the elimination of continuous power supply and complex instrumentation. Here, CL‐induced cationic photopolymerization using ferrocenium salts as unimolecular photoinitiators is reported. The ferrocenium salts, facilely synthesized via ligand exchange reactions, absorb the visible light emitted from CL reactions and generate Lewis acids capable of initiating the cationic polymerization of oxirane and vinyl monomers. The presented method can be applied to create linear polymer chains and cross‐linked luminescent polymer networks, which have significant potential in the fabrication of new polymeric materials and various bioapplications.

Macro peroxide initiators based on autoxidized unsaturated plant oils: Block/graft copolymer conjugates for nanotechnology and biomedical applications

AbstractThe autoxidation of unsaturated fatty acids and their esters is one of the most important reactions in food and biological systems. Autoxidation is a type of reaction between air oxygen and unsaturated plant oils. This reaction starts with a hydrogen abstraction on the methylene group adjacent double bond, leaving a radical onto the carbon atom. Molecular oxygen attacks this radical leading to produce peroxide and hydroperoxide derivatives of the oligomerized unsaturated plant oils. Because peroxide groups thermally cleave to produce free radicals, hydroperoxide derivatives of unsaturated plant oil oligomers can be used in the free radical polymerization of vinyl monomers leading to the related block/graft copolymers. The obtained copolymers combined with the biodegradable natural plant oil gain superior properties such as biodegradability and softness. In this review article, the in vitro autoxidation of well‐known unsaturated plant oils‐soybean oil, linseed oil, and castor oil and some related unsaturated fatty acids‐oleic acid, linoleic acid, and ricinoleic acid was carried out under atmospheric conditions with or without exposing white light. Because the autoxidized unsaturated oil/fatty acids contain peroxide/hydroperoxide groups (they are referred to as macro peroxide initiators) that they are used in the free radical polymerization of vinyl monomers to obtain block/graft copolymers. The improved polymerization conditions, characterization, and applications of the obtained products will be discussed.

Modelling of polymerization kinetics and molar mass development in the nitroxide‐mediated polymerization (NMP) of styrene in supercritical carbon dioxide using the PC‐SAFT equation of state

AbstractA mathematical model for polymerization kinetics and molar mass development in the nitroxide‐mediated polymerization (NMP) of vinyl monomers in supercritical carbon dioxide (scCO2) has been developed. The method of moments is used for molar mass development. The perturbed‐chain statistical associating fluid theory (PC‐SAFT) equation of state is used to estimate the number of stable phases present at equilibrium in the reaction mixture, critical number average chain length at which polymer particles are formed, and monomer concentration in each phase. Pure and binary PC‐SAFT interaction parameters are estimated from liquid–liquid equilibrium (LLE) and liquid–vapour equilibrium (LVE) experimental data at 60 to 129°C. The effect of pressure on monomer conversion and molar mass development in the polymerization of styrene (Sty) using benzoyl peroxide (BPO) and 2,2,6,6‐Tetramethylpiperidinyl‐1‐oxyl (TEMPO) at 120°C and 300–500 bar is studied. It was observed that increasing pressure increases polymerization rate without significantly affecting molar mass development.

SYNTHESIS AND PROPERTIES OF POLYMER SUSPENSIONS OBTAINED BY HETEROPHASE POLYMERIZATION IN THE PRESENCE OF α,ω BIS[3 GLYCIDOXYPROPYL]POLYDIMETHYLSILOXANE

Polymeric microspheres with glycidoxy groups on the surface can be used as bioligand carriers in diagnostic test systems. However, the possibility of synthesizing aggregatively stable functional polymeric microspheres in a wide range of diameters is an urgent problem of modern polymer chemistry. This article is devoted to a systematic study of the kinetics of styrene and methyl methacrylate polymerization in the presence of an organosiloxane surfactant with terminal glycidoxy groups – α,ω-bis[3-glycidoxyproopyl]-polydimethylsiloxane, PDMS(CHOCH2). The article shows the influence of phases volume ratio, initiator and surfactant concentration, synthesis temperature and pH of initial medium on the properties of polymer suspensions (their aggregative stability, monodispersity, particle diameter). The formation of polymer-monomer particles during polymerization has been studied and it has been shown that polymer suspensions retain high aggregation stability from early period of monomer conversion, and the particle diameter changes untill 30% of the monomer conversion. Due to the high surface activity of the organosiloxane surfactant used and its incompatibility with the resulting polymer, aggregatively stable functional polymer suspensions with diameters from 0.09 to 1.1 μm were obtained by a single-stage synthesis. Studies of the hydration degree of polymer microspheres have shown that the presence of functional glycidoxy groups on their surface ensures the formation of a hydration shell, which increases the stability of polymer particles, and also makes it possible to use the resulting microspheres as carriers of bioligands. Thus, the use of water-insoluble organosiloxane surfactants as stabilizers for the heterophase polymerization of vinyl monomers makes it possible to synthesize aggregatively stable functional polymer suspensions in a wide range of diameters. The use of organosiloxane surfactants with various functional groups expands the range of functional polymer microspheres used in various fields of application.