Comonomer Reactivity Ratios Research Articles

Synthesis and Properties of Vinyl Ether and Acrylonitrile Copolymers

AbstractThe radical copolymerizations of vinyl ethers, including ethylene glycol monovinyl ether (HEVE) and isobutyl vinyl ether (IBVE), and acrylonitrile (AN) are investigated. The reactivity ratios of comonomers are evaluated by Fineman–Ross (rHEVE = 0.032 and rAN = 1.054, and rIBVE = 0.031 and rAN = 13.984) and Kelen–Tudos (rHEVE = 0.001 and rAN = 1.036, and rIBVE = 0.032 and rAN = 13.981) methods, respectively. The conversions of HEVE and IBVE under similar conditions also support that HEVE has a higher reactivity than that of IBVE. A series of poly(HEVE‐co‐AN)s (Mn from 56 000 to 110 000) and poly(IBVE‐co‐AN)s (Mn from 52 000 to 97 000) with random sequential structure are prepared. Furthermore, the glass transitional temperatures of poly(vinyl ether‐co‐AN)s decrease with the increase of vinyl ether units in the copolymers. Thermal stability of poly(vinyl ether‐co‐AN)s is comparable, which is slightly affected by vinyl ether contents. Poly(HEVE‐co‐AN)s possess a two‐stage weight loss (one around 230 °C, and the other around 300 °C), and poly(IBVE‐co‐AN)s decompose at around 350 °C with one stage. In addition, the poly(HEVE‐co‐AN)s demonstrate a good hydrophilicity of which the average of static water contact angles decrease from 85.4° to 62.4° with the HEVE units increased from 8% to 33%.

Organosilicon copolymers containing triazole and triethoxysilyl groups as the basis for promising functional hydrophobic materials

New functional heat-resistant poly (1-vinyl-1,2,4-triazole-co-triethoxyvinylsilane) (poly (VT-co-TEVS)) copolymers of various compositions containing triazole and triethoxysilyl groups in the side chains were synthesized by radical copolymerization. Elemental analysis, Fourier transform infrared spectroscopy, NMR spectroscopy, gel permeation chromatography, dynamic light scattering, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry were used to study the composition and structure of poly (VT-co-TEVS) copolymers. The weight average molecular weight of the copolymers varies from 21 to 174 kDa. The reactivity ratios of comonomers in copolymerization (rVT = 4.004 and rTEVS = 0.227) indicate the high reactivity of VT. The resulting copolymers exhibit high thermal stability up to 270 °C. Modification of flexible chain poly (VT-co-TEVS) copolymers was carried out using hydrolytic polycondensation of triethoxysilyl groups. Monitoring of the hydrodynamic diameters of the synthesized copolymers showed intermacromolecular crosslinking of polymer chains due to the formation of Si–O–Si siloxane bonds. Based on spatially cross-linked polyorganosiloxanes containing a functional 1,2,4-triazole fragment, hydrophobic heat-resistant polymeric materials were obtained.

Early bird gets the network: The relative importance of reactivity ratios, Ψ parameter, and crosslinker level on gel formation in FRP

AbstractNetwork topology is manipulated in free‐radical copolymerization via proper selection of crosslinker type and its respective properties when paired with specific monomers. Our prior work has focused on the impact of the reduced reactivity parameter Ψ applied to a pendent vinyl, characteristic for each monomer/crosslinker pair, yet here we assess the relative importance of the comonomer reactivity ratios to see whether one factor can counterbalance the other. The traditional reactivity ratio determines when the crosslinker molecule is incorporated into the polymer backbone, while the reduced reactivity Ψ parameter relates to the efficiency of the resulting pendent side chain vinyl being utilized to form a crosslink node at some later point during the polymerization. Both factors are then contrasted with simply the overall loading of crosslinker. Either n‐butyl methacrylate (n‐BMA) or styrene (STY) was chosen as a primary backbone monomer to copolymerize with one of three crosslinkers: 1,4‐butanediol dimethacylate (BDDMA), 1,4‐butanediol diacrylate (BDDA), or divinylbenzene (DVB). Both kinetics and gel can be most dramatically boosted when a crosslinker is applied having a reactivity ratio favouring early insertion. This in turn leads to an earlier onset of gel formation, which ultimately results in greater final gel content. This amplification of both kinetics and gel can overcome an otherwise small Ψ due to crosslinker or main monomer choice. This reactivity ratio effect was further confirmed by Monte Carlo simulations. By whatever mechanism (higher Ψ, lower rA, or higher crosslinker level), earlier onset of gelation produces more gel overall and a tighter network topology.

Construction of Aluminum‐Porphyrin‐Based Hypercrosslinked Ionic Polymers (HIPs) by Direct Knitting Approach for CO2 Capture and In‐Situ Conversion to Cyclic Carbonates

AbstractHypercrosslinked polymers (HCPs) constructed by Friedel‐Crafts reaction have drawn increasing attention in recent decades, but their multifunctionalization remains a huge challenge. Herein, a series of aluminum‐porphyrin‐based hypercrosslinked ionic polymers have been successfully synthesized by direct knitting approach without additional electrophilic comonomers, which involves the copolymerization of neutral porphyrin monomers and ionic building. By increasing the connected nodes numbers of ionic monomers, the introduction of abundant tetraphenylmethane fragements into the porphyrin backbones endows them with high‐density ionic active sites. Accordingly, the well‐matched molar ratios of aluminum sites to nucleophilic chloride anions that work synergistically for CO2/epoxide coupling can be achieved. Al‐HIP‐2 with flexible ionic pendants and a high Al/Cl ratio allows CO2 cycloaddition to be performed at ambient conditions or with diluted CO2; while Al‐HIP‐3 with rigid ionic moieties and a relatively low Al/Cl ratio exhibits higher specific surface area and stronger CO2 capture ability. Therefore, this co‐condensation strategy provides a simple and feasible pathway for adjusting the reactivity ratios of comonomers via simple structural changes in the knitting process, thus achieving the rational construction of multifunctionalized HCPs for CO2 capture and in‐situ conversion to cyclic carbonates.

Macrocyclic Allylic Sulfone as a Universal Comonomer in Organocatalyzed Photocontrolled Radical Copolymerization with Vinyl Monomers

Radical copolymerization of vinyl monomers and cyclic monomers is a versatile approach to degradable vinyl plastics. Despite recent advances, a class of “universal” cyclic monomers that possess broad reactivities with various types of vinyl monomers remains elusive. Herein, we report a general method for the organocatalyzed photocontrolled radical ring-opening cascade copolymerization (rROCCP) of macrocyclic allylic sulfone and various types of vinyl monomers, including acrylates, acrylamides, styrene, and methacrylate. Catalyzed by Eosin Y under visible light irradiation, the copolymerization of macrocyclic allylic sulfone and acrylic monomers displayed near unity comonomer reactivity ratios by fitting the copolymer composition to the Beckingham–Sanoya–Lynd integrated model. Macrocyclic allylic sulfone was also successfully copolymerized with styrene (r1 = 3.02 and rSt = 0.35) or methyl methacrylate (r1 = 0.18 and rMMA = 5.81) to generate degradable polystyrene and poly(methyl methacrylate). These degradable vinyl copolymers exhibited tunable thermal properties correlated with the incorporation of the degradable main-chain diester motif. The unprecedented reactivities that macrocyclic allylic sulfone demonstrated in the organocatalyzed photocontrolled rROCCP provide a general approach to the wide range of degradable vinyl plastics with various structures and functions.

High-Surface-Area Metalloporphyrin-Based Porous Ionic Polymers by the Direct Condensation Strategy for Enhanced CO2 Capture and Catalytic Conversion into Cyclic Carbonates.

Metalloporphyrin-based porous organic polymers (POPs) that behave as advanced biomimetic nanoreactors have drawn continuous attention for heterogeneous CO2 catalysis in the past decades. Inspired by the double activation model of epoxides, the design and synthesis of metalloporphyrin-based porous ionic polymers (PIPs) are considered as one of the most promising approaches for converting CO2 to cyclic carbonates under cocatalyst- and solvent-free conditions. To overcome the obstacle of poor reaction activity of ionic monomers or highly irregular stacking architecture, in this paper, we have proposed and demonstrated a modular bottom-up approach for constructing a series of high-surface-area metalloporphyrin-based PIPs in high yields by the direct condensation strategy, thus boosting the close contact of multiple active sites and achieving the enhanced CO2 capture and catalytic conversion into cyclic carbonates with high turnover frequencies under mild conditions. These recyclable aluminum-porphyrin-based PIPs are featured with high surface areas, prominent CO2 adsorptive capacities, rigid porphyrin skeletons, and flexible ionic pendants, as well as the matched amounts and spatial positions of metal centers and ionic sites, in which is demonstrated to be one of the quite competitive catalysts. Therefore, this strategy of introducing ionic components into the porphyrin frameworks as flexible side chains rather than main chains and adjusting the reactivity ratios of comonomers by structure-oriented methods, provides feasible guidance for the multifunctionalization of metalloporphyrin-based POPs, thereby increasing the accessibility of multiple active sites and improving their synergistic catalytic behavior.

Insertion of ester bonds in three terpolymerization systems

Nonbiodegradable (co)polymers with all-carbon backbone produced via radical polymerization are used in various applications. For some applications, like for example in skincare and haircare, these polymers are nonrecoverable and therefore would be preferably made biodegradable. Therefore, inserting ester bonds in the backbone via radical ring opening terpolymerization of acrylates and 2-methylene-1,3 dioxepane (MDO) could be a suitable approach to obtain biodegradable terpolymers. This report investigates the influence of batch versus semibatch process on the polymerization of three terpolymerization systems viz. (i) methacrylamide (MAAM)/n-butyl acrylate (nBA)/BMDO (5,6-Benzo-2-Methylene-1,3-Dioxepane), (ii) MAAM/nBA/MDO, and (iii) methyl methacrylate (MMA)/VAc (vinyl acetate) /MDO. We demonstrate the improvement in number of ester groups inserted and the homogeneity of insertion via semibatch polymerization processes. The process is guided via optimal monomer addition feeding profiles generated using the reactivity ratios of comonomers. Such improved insertion was demonstrated by the molecular weight distribution of fragments after alkali degradation in the investigated systems.

Preparation and identification of green polymers towards the production of sustainable latex from β-myrcene and some methacrylate monomers

Sustainable polymers have enough potential to overcome petroleum materials and not completely rely on them for the presence of renewable raw materials, as well as the possibility of developing polymerization methods for renewable raw materials to have these materials recyclability, biodegradability and being a non-toxic material. This has been the focus of recent years. Solvent-free emulsion copolymerization of β-myrcene, a naturally occurring monoterpene monomer, the co-monomers that were used with β-myrcene, tetrahydrofurfuryl methacrylate, iso-bornyl methacrylate, and tert-butyl methacrylate, and each methacrylate monomer was polymerized separately with β-myrcene monomer, β-myrcene –methacrylate monomer (MY/MA) copolymers of different compositions were synthesized under nitrogen atmosphere at 60 ºC, using copolymers composition 50/50 comonomer reactivity ratios, and has been added sodium dodecyl sulfate as emulsifier, and ammonium persulfate as initiator. 1H-NMR, 13CNMR and FTIR spectroscopy were used to confirm the chemical structure and composition. It was found that the copolymerization reaction of each copolymer is influenced with the form of the methacrylate(s) side chain. Furthermore, the thermal properties of copolymers were characterized by DSC and TGA, where the value Tg indicate that random composition copolymers, due to the difference in crystallization of each side chain.

Degradable Vinyl Random Copolymers via Photocontrolled Radical Ring-Opening Cascade Copolymerization.

Degradable vinyl polymers by radical ring-opening polymerization are promising solutions to the challenges caused by non-degradable vinyl plastics. However, achieving even distributions of labile functional groups in the backbone of degradable vinyl polymers remains challenging. Herein, we report a photocatalytic approach to degradable vinyl random copolymers via radical ring-opening cascade copolymerization (rROCCP). The rROCCP of macrocyclic allylic sulfones and acrylates or acrylamides mediated by visible light at ambient temperature achieved near-unity comonomer reactivity ratios over the entire range of the feed compositions. Experimental and computational evidence revealed an unusual reversible inhibition of chain propagation by in situ generated sulfur dioxide (SO2 ), which was successfully overcome by reducing the solubility of SO2 . This study provides a powerful approach to degradable vinyl random copolymers with comparable material properties to non-degradable vinyl polymers.

Degradable Vinyl Random Copolymers via Photocontrolled Radical Ring‐Opening Cascade Copolymerization**

AbstractDegradable vinyl polymers by radical ring‐opening polymerization are promising solutions to the challenges caused by non‐degradable vinyl plastics. However, achieving even distributions of labile functional groups in the backbone of degradable vinyl polymers remains challenging. Herein, we report a photocatalytic approach to degradable vinyl random copolymers via radical ring‐opening cascade copolymerization (rROCCP). The rROCCP of macrocyclic allylic sulfones and acrylates or acrylamides mediated by visible light at ambient temperature achieved near‐unity comonomer reactivity ratios over the entire range of the feed compositions. Experimental and computational evidence revealed an unusual reversible inhibition of chain propagation by in situ generated sulfur dioxide (SO2), which was successfully overcome by reducing the solubility of SO2. This study provides a powerful approach to degradable vinyl random copolymers with comparable material properties to non‐degradable vinyl polymers.

Effect of the Configuration of a Bulky Aluminum Initiator on the Structure of Copolymers of l,l-Lactide with Symmetric Comonomer Trimethylene Carbonate.

The effect of configuration of an asymmetric bulky initiator 2,2′-[1,1′-binaphtyl-2,2′-diyl- bis-(nitrylomethilidyne)]diphenoxy aluminum isopropoxide (Ini) on structure of copolymer of asymmetric monomer l,l-lactide (Lac) with symmetric comonomer trimethylene carbonate (Tmc) was studied using polarimetry, dilatometry, Size Exclusion Chromatography (SEC), and Carbon Nuclear Magnetic Resonance (13C NMR). When the S-enantiomer of Ini was used the distribution in copolymer chains at the beginning of polymerization is statistical, with alternacy tendency, changing next through a gradient region to homoblocks of Tmc. However, when R-Ini was used, the product formed was a gradient oligoblock one, with Tmc blocks prevailing at the beginning, changing to Lac blocks dominating at the end part of chains. Initiation of copolymerization with the mixture of both initiator enantiomers (S:R = 6:94) gave a multiblock copolymer of similar features but shorter blocks. Analysis of copolymerization progress required complex analysis of dilatometric data, assuming different molar volume contraction coefficients for units located in different triads. Comonomer reactivity ratios of studied copolymerizations were determined.

Continuous-flow chemistry for the determination of comonomer reactivity ratios

Continuous-flow chemistry provides an operationally simple and reproducible method for the determination of comonomer reactivity ratios in a single afternoon.

Synergetic Effect of Monomer Functional Group Coordination in Catalytic Insertion Polymerization.

PhS- and PhNH-functionalized dienes are copolymerized efficiently with butadiene to stereoregular copolymers by [(mesitylene)Ni(allyl)][BArF4] (Ni-1). Overall polymerization rates and comonomer incorporations depend strongly on the linker length between the diene moiety and functional group, in, e.g., PhS-(CH2)xC(═CH2)-CH═CH2 (PhS-x-BD, x = 3-7), in particular for certain linker lengths high comonomer reactivity ratios stand out. This effect is related to a favorable binding of the comonomer to the active site comprising coordination of its functional group, which significantly enhances comonomer incorporation in the growing polymer chain.

Tuning the Molar Composition of "Charge-Shifting" Cationic Copolymers Based on 2-(N,N-Dimethylamino)Ethyl Acrylate and 2-(tert-Boc-Amino)Ethyl Acrylate.

Copolymers of 2-(N,N-dimethylamino)ethyl acrylate (DMAEA) and 2-(tert-Boc-amino)ethyl acrylate (tBocAEA) are synthesized by reversible addition-fragmentation chain transfer polymerization in a controlled manner with defined molar masses and narrow molar masses distributions (Ð ≤ 1.17). Molar compositions of the P(DMAEA-co-tBocAEA) copolymers are assessed by means of 1 H NMR. A complete screening in molar composition is studied from 0% of DMAEA to 100% of DMAEA. Reactivity ratios of both comonomers are determined by the extended Kelen-Tüdos method (r DMAEA = 0.81 and rtBocAEA = 0.99).

Colloidal Random Terpolymers: Controlling Reactivity Ratios of Colloidal Comonomers via Metal Tipping.

We report on a versatile synthetic method of preparing colloidal copolymers and terpolymers composed of dipolar Au@Co core-shell nanoparticles (NPs) in the backbone, along with semiconductor CdSe@CdS nanorod (NR), or tetrapod (TP) side chain groups. A seven-step colloidal total synthesis enabled the synthesis of well-defined colloidal comonomers composed of a dipolar Au@CoNP attached to a single CdSe@CdS NR, or TP, where magnetic dipolar associations between Au@CoNP units promoted the formation of colloidal co- or terpolymers. The key step in this synthesis was the ability to photodeposit a single AuNP tip onto CdSe@CdS NR or TP that enables selective seeding of a dipolar CoNP onto the AuNP seed. We show that the variation of the AuNP size directly controlled the size and dipolar character of the CoNP tip, where the size modulation of the Au and Au@CoNP tips is analogous to control of comonomer reactivity ratios in classical copolymerization processes.

Correction: Determining chemospecificity in reactions with chain transfer agent and corresponding radical via evaluation of molecular weight dependency of apparent comonomer reactivity ratios: free-radical copolymerization of vinyl acetate and dibutyl maleate

Correction for ‘Determining chemospecificity in reactions with chain transfer agent and corresponding radical via evaluation of molecular weight dependency of apparent comonomer reactivity ratios: free-radical copolymerization of vinyl acetate and dibutyl maleate’ by Seyed Saeid Rahdar et al., RSC Adv., 2016, 6, 109759–109768.

Determining chemospecificity in reactions with chain transfer agent and corresponding radical via evaluation of molecular weight dependency of apparent comonomer reactivity ratios: free-radical copolymerization of vinyl acetate and dibutyl maleate

Performing copolymerization with two different conditions leading to different molecular weights allows us to determine trichloromethyl radical reactivity towards comonomers.

Estimating Monomer Sequence Distributions in Tetrapolyacrylates

Recently Ting et al. [ACS Macro Lett. 2013, 2, 770−774] described the syntheses of acrylic tetrapolymers with controlled molecular weights and tetramonomer compositions. Relative reactivity ratios of all monomer pairs were determined and used in the Walling–Briggs terminal copolymerization model along with Skeist’s equations to address the expected compositional drift in the monomer feed ratios. The anticipated control of monomer incorporation based on this approach was verified experimentally on several tetrapolyacrylates synthesized by RAFT polymerization, which additionally controlled their molecular weights. Their “new and simple paradigm combining both predictive models provides complementary synthetic and predictive tools for designing macromolecular chemical architectures with hierarchical control over spatially dependent structure–property relationships for complex applications” is extended here to the derivation of expected monad compositions, and diad, triad, and tetrad monomer sequence distributions. These were obtained directly from the comonomer reactivity ratios determined experimentally by Ting et al. Our motivation was twofold: (i) The similar chemical structures of the four acrylate monomers they selected (methyl, 2-carboxyethyl, 2-hydroxypropyl, and 2-propylacetyl acrylate) render the experimental determination of sequence distributions in the resulting tetrapolyacrylates problematic. (ii) Because they are spatially dependent structural parameters, the sequence distributions of monomer diads, triads, tetrads, etc., in co-, tri-, tetrapolymers, etc., are generally expected to correlate more closely with their properties than their overall compositions.

Microstructure determination of isobornyl methacrylate-styrene copolymer by NMR spectroscopy

An investigation of the microstructure of isobornyl methacrylate - styrene (I/S) copolymers prepared by the atom transfer radical polymerization (ATRP) using methyl-2-bromopropionate as an initiator and PMDETA copper complex as catalyst under nitrogen atmosphere at 70 °C has been done by two-dimensional NMR techniques. 2D- HSQC and TOCSY have been utilized to resolve the complex 1H NMR spectrum and to establish the compositional and configurational sequences of isobornyl methacrylate-styrene (I/S) copolymers. 2D HSQC and TOCSY spectra showed compositional and configurational sensitivity of α-methyl carbon of I unit and methine proton of S unit and are assigned up to the triad level. The methylene carbon (C10) also shows triad level of compositional sensitivity in 2D HSQC spectra. Heteronuclear multiple-bond correlation (HMBC) spectroscopy has been used to study carbonyl/quaternary carbon-proton coupling. The carbonyl and quaternary carbons showed compositional and configurational sensitivity upto the triad level. The values of reactivity ratios were determined by Kelen-Tudos (KT) and nonlinear error in variable method (RREVM) using copolymer composition data that were determined by 1H NMR spectrum. Reactivity ratios of co-monomers in I/S copolymer, determined from a linear Kelen-Tudos method (KT) and non-linear Error-in-Variable Method (EVM), are rI = 0.39 ± 0.09, rS = 0.44 ± 0.08 and rI = 0.42, rS = 0.47, respectively.

Copolymerization of amine-containing monomers and dodecyl (meth)acrylate in toluene: controlling compositional heterogeneity

The radical copolymerizations of N-[(3-dimethylamino)propyl]methacrylamide (DMAPMA) with n-dodecyl acrylate (DA) or n-dodecyl methacrylate (DMA) in toluene (70 °C) were shown to have a peculiar nature: the total initial concentration of monomers significantly influences the composition and compositional heterogeneity of copolymers. Such processes can not be adequately described using the comonomer reactivity ratios. No concentration effects were found in the copolymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and n-dodecyl methacrylate in toluene; the calculated comonomer reactivity ratios were respectively 1.57 ± 0.20 and 0.83 ± 0.02. The differences in the behavior of systems involving amine monomers are related to the ability of DMAPMA to form assemblies with different reactivity due to the hydrogen bonding.