Donor Monomers Research Articles

Spin Trapping of Radicals from the Reactions between Donor and Acceptor Olefins. Further Evidence for the Tetramethylene Diradical Intermediate as the Initiator of Spontaneous Copolymerization

EPR spectroscopy and product isolation have been used to investigate the initiation of spontaneous copolymerizations of donor and acceptor monomers. The results establish the presence of tetramethy ...

Ultrafast excitation transfer and relaxation in linear and crossed-linear arrays of porphyrins

Abstract

Radical copolymerization reactivity of methacryloyl-terminated poly(ethylene glycol methylether) with vinylbenzyl-terminated polystyrene macromonomers

Free-radical copolymerizations of vinylbenzyl-terminated polystyrene (PS-VM; M 1) and methacryloyl-terminated poly(ethylene glycol methylether) (PEG-MC; M 2) were carried out in various solvents (benzene, 1,4-dioxane and N, N-dimethylformamide). The reactivity ratios obtained for the binary macromonomer systems were different from corresponding model system of styrene and methyl methacrylate ( r 1=0.52 and r 2=0.46) due to phase separation. PEG macromonomers could not interpenetrate sufficiently into propagating copolymer chains that had radical sites due to phase separation. On the other hand, the reactivity ratios ( r 1=0.25 and r 2=0.02) obtained for the binary copolymerizations of PS-VM and PEG-MC/tin tetrachloride macromonomers showed strong alternation. It was suggested that alternation results from the homopolymerization of 1:1 complexs formed between the donor and acceptor monomers.

Kinetic study of the photo-induced copolymerization of N-substituted maleimides with electron donor monomers

The photo-induced copolymerization of electron donor/electron acceptor monomers has been studied by real-time infrared spectroscopy. With maleimide/vinyl ether mixtures, the reaction was found to proceed rapidly upon u.v. exposure in the absence of oxygen to reach nearly 100% conversion within seconds. The two monomers disappeared at similar rates, with formation of an alternating copolymer. Similar results were obtained with maleimide/ N-vinylpyrrolidone and maleimide/styryloxy combinations. Highly crosslinked polymer networks have been produced by photo-induced copolymerization of bis-maleimide and divinyl ether monomers. These photoinitiator-free formulations were found to be less sensitive to oxygen inhibition than typical u.v.-curable acrylate resins. N-substituted maleimides were also shown to act as monomeric photoinitiators by inducing the polymerization of acrylate monomers upon u.v. irradiation.

Determination of triad sequence distribution of copolymers of maleic anhydride and its derivates with donor monomers by 13C n.m.r. spectroscopy

Several alternating and semi-alternating copolymers were analysed by quaternary 13C n.m.r. spectroscopy. The aromatic `next to polymer chain' carbon (C7) of donor monomer (1) units is sensitive to the unit 1-centred triad sequence distribution. The acceptor monomer is referred to as 0. The chemical shifts of the non-alternating (111), semi-alternating (011+110) and alternating (010) triad sub-peaks were assigned in ppm in Table 1Table 1Copolymer of monomer with monomer 1111011(+)110010 triad sequenceMaleic anhydride with styrene147.5145146141.5140.5136.5Maleic anhydride with trans-stilbene138132Maleic anhydride with α-methylstyrene152148148 (145.5)142.5139Maleic anhydride with allylbenzeneNot sensitive to triad sequence distribution and appears at 142–139ppmCitraconic anhydride with styrene147.5145147143.5137.5Bromomaleic anhydride with styrene147.5145141.5140136.5Dichloromaleic anhydride with styrene147.5145141.5138133Maleimide with styrene147.5145140.5136.5.

Photopolymerization of Dialkylfumarates with Electron Donor Monomers via Charge-Transfer Complex.

Fumarate esters with abstractable hydrogens were found to copolymerize via photoinitiation with a variety of electron donor monomers at a relatively rapid rate under both air and nitrogen. Under air, their copolymerization rates were much faster than monofunctional or difunctional acrylates when a photoinitiator was used to initiate polymerization. Mixtures of dialkylfumarates and N-vinyl formamide (NW) had copolymerization rates faster than dialkylfumarates and N-vinyl pyrrolidone or vinyl ethers. Similar correlations were observed regardless of addition of photoinitiator. From the curing test, difunctional fumarate/NVF system showed faster curing speed than those of multifunctional acrylate with photoinitiator systems.

Synthesis and Properties of Alternating Acceptor−Donor Copolymers of Squaric Acid with 1-Dodecyl- and 3-Dodecylpyrroles

Polycondensation between the acceptor−donor monomer combination of squaric acid with 1-dodecyl- and 3-dodecylpyrroles provided conjugated macromolecules having two types of isomeric repeating units, depending upon the reaction conditions employed. Under azeotropic distillation using the 1-butanol−benzene solvent mixture (route A), the most preferred 1,3-zwitterionic repeating units were mostly formed, whereas in DMSO−acetic acid solvent under room temperature (route B), considerable amounts of the isomeric 1,2-diketonic repeating units were also formed along with the zwitterionic repeating units. Evidence for the structural differences of the polycondensation products obtained by routes A and B could be obtained from the detailed IR spectral analysis and studies of their physical properties such as solubility, molecular weight, optical absorption, solvatochromism, and conducting properties. The solubilities and the molecular weights of the polycondensation products having 1,2-diketonic repeating units obt...

Synthesis of protective coatings on steel by surface spontaneous polymerization

We have previously reported a new method for applying protective coatings on metal surfaces, the surface spontaneous polymerization process. Polymerization occurs spontaneously on the substrate upon immersion into a monomer solution, forming a layer of uniform coating in situ. A redox mechanism was proposed to explain the spontaneous initiation [1] . In this paper, we report studies of the propagation mechanism involving several monomer systems. It was found that propagation via both a charge transfer complex and addition of free monomers is possible, and also that both mechanisms can be operating at the same time. This is the case for the 4-carboxyphenyl maleimide (4CPMI)/styrene/acrylonitrile system, in which the donor monomer, styrene, forms a charge transfer complex with the strong acceptor monomer, 4CPMI, and copolymerizes alternatingly while the other acceptor monomer, acrylonitrile, is incorporated randomly. The surface spontaneous polymerization process can therefore be used to copolymerize a wide variety of monomers to yield coatings with desired properties.

Complex-radical copolymerization of 2,4,4-trimethylpentene-1 with maleic anhydride

The mechanism of radical copolymerization of 2,4,4-trimethylpentene-1 (TMP) as donor monomer with maleic anhydride (MA) as acceptor monomer in the presence of benzoyl peroxide is discussed. The constant of charge transfer complex ( K c) and copolymerization parameters ( r 1, r 2, r 1c, r 1c1, r 1c2, Q 1 and e 1) have been determined; their values are as follows: K c=0.27±0.1 L/mol and 0.16±0.07 L/mol at 35°C in CH 3COCH 3-d 6 for TMP–TMA and n-octene–MA (model system) complexes; r 1=0.12±0.005, r 2=0.38±0.02, r 1c=0.0068, r 1c1=0.127 and r 1c2=0.0072; Q 1=0.0012 and e 1=0.49. Some kinetic parameters of the reaction and quantitative contributions of TMP–MA complex to reactivity ratios of the monomers have been studied and their contribution to chain growth are estimated as: k 12/ k 21=3.51, k 1c/ k 12=0.98 and k 2c/ k 21=1.03. The copolymerization is found to proceed predominantly by the “mixed” mechanism with equal participation of complex-bound and free monomers in propagation. A solvent effect in radical copolymerization of TMP with MA is observed. The higher rate of copolymerization in the TMP–MA–dimethylformamide system is explained by the effect of the MA–solvent complex increasing the acceptor properties of the MA molecule.

Photopolymerization of dialkyl fumarates with electron donor monomers

Fumarate esters with abstractable hydrogens were found to copolymerize via photoinitiation with a variety of electron donor monomers at a relatively rapid rate both in air and in nitrogen. In air, copolymerization rates of the dialkyl fumarates made from reaction of fumaric chloride with 1-methoxyisopropanol or 2-methoxy-1-ethanol were much faster than for monofunctional or difunctional acrylates when a photoinitiator was used to initiate polymerization. Mixtures involving dialkyl fumarates and N-vinylformamide (NVF) had polymerization exotherm rates faster than when N-vinylpyrrolidone and vinyl ethers were used as comonomers. Similar correlations with fumarate structure were observed when photoinitiator was present or absent, but faster rates were always obtained when a photoinitiator was present.

Alternating Copolymerization of Maleimide and Ethyl Atropate Without Initiator

ABSTRACT The copolymerization of maleimide(MI)(M1) and ethyl atropate (EAP)(M2) was carried out by self-initiation at 60°C, in which M2(Q=0.43, e=0.92) and M1 (Q=0.44, e=1.35) constituted a pair of electron donor and acceptor monomers on Price-Alfrey equation. A high alternating tendency was observed, the monomer reactivity ratios r1 =0.048±0.016 and r2=0.12±0.012 were calculated by a nonlinear least-squares procedure. The spontaneous alternative copolymerization is considered to be carried out by the induced radicals produced via a contact-type charge transfer complex between M1 and M2, which was confirmed by UV spectra. Thermogravimetric analysis (TGA) shows that the resulting copolymers have high thermal stability.

The influence of charge-transfer complexes on the copolymerization behavior of cyclic maleic acid derivatives with donor monomers

The influence of charge-transfer complexes on the copolymerization behavior of cyclic maleic acid derivatives with donor monomers

The influence of charge-transfer complexes on the copolymerization behavior of cyclic maleic acid derivatives with donor monomers

The acceptor monomers maleic anhydride (MSA), itaconic anhydride (ISA), N-phenylmaleimide (NPI) and N-cyclohexylmaleimide (CMI) were combined with the donor monomers styrene (ST), butyl vinyl ether (BV) and N-vinyl-2-pyrrolidone (NVP) and studied by means of UV spectroscopy using CT bands. In this manner, the 1:1 stoichiometry of the CT complexes, the equilibrium constant in the range of 20°C to 60°C, and the thermodynamic equilibrium data were determined. Additionally, Monte-Carlo simulations of the donor-acceptor combinations in the presence of solvent molecules were run. The cohesion energies calculated from these simulations were used to quantify the donor-acceptor interactions and showed good agreement with the UV spectral data. The acceptor strength decreases in the order MSA > NPI > ISA > CMI, the donor strength in the order of NVP > ST > BV. In the free radical solution copolymerization of the systems NVP/NPI, BV/NPI, acrylonitrile (AN) AN/CMI, AN/NPI, MSA/CMI and MSA/NPI, the reaction rate and molecular weight dependence on the monomer combination, as well as the r-values were determined. Using the Kc-values, conclusions were drawn concerning the different reaction mechanisms. The properties of the polymers were investigated using differential scanning calorimetry (DSC) and thermogravimetry.

The influence of charge-transfer complexes on the copolymerization behavior of cyclic maleic acid derivatives with donor monomers

The acceptor monomers maleic anhydride (MSA), itaconic anhydride (ISA), N-phenylmaleimide (NPI) and N-cyclohexylmaleimide (CMI) were combined with the donor monomers styrene (ST), butyl vinyl ether (BV) and N-vinyl-2-pyrrolidone (NVP) and studied by means of UV spectroscopy using CT bands. In this manner, the 1:1 stoichiometry of the CT complexes, the equilibrium constant in the range of 20°C to 60°C, and the thermodynamic equilibrium data were determined. Additionally, Monte-Carlo simulations of the donor-acceptor combinations in the presence of solvent molecules were run. The cohesion energies calculated from these simulations were used to quantify the donor-acceptor interactions and showed good agreement with the UV spectral data. The acceptor strength decreases in the order MSA > NPI > ISA > CMI, the donor strength in the order of NVP > ST > BV. In the free radical solution copolymerization of the systems NVP/NPI, BV/NPI, acrylonitrile (AN) AN/CMI, AN/NPI, MSA/CMI and MSA/NPI, the reaction rate and molecular weight dependence on the monomer combination, as well as the r-values were determined. Using the Kc-values, conclusions were drawn concerning the different reaction mechanisms. The properties of the polymers were investigated using differential scanning calorimetry (DSC) and thermogravimetry.

Polymers from multifunctional isocyanates 14. Alternating copolymers from isocyanato alkenes: Copolymerization of 2-propenyl isocyanate with trimethylsilyl methacrylate as electron acceptor monomer

The copolymerization of 2-propenyl isocyanate (1) with trimethylsilyl methacrylate (2) has been investigated. 1 is an electron donor monomer with little tendency to undergo homopolymerization, while 2 is an electron acceptor monomer, capable of free radical homopolymerization. Polymerization to low conversion in benzene gave copolymers with preferential incorporation of 2 and a tendency towards alternating copolymers with increasing amounts of 1 in the feed (1 : 1.13 with a 9 : 1 feed ratio of monomers 1 : 2). The glass transition temperatures of the amorphous polymers are in the range from 100–70°C, with a Tg of poly(trimethylsilyl methacrylate) being 135°C. Desilylation occurs in the presence of water, causing an exothermal reaction above the glass transition temperature probably with formation of amides, a reaction that can be used for crosslinking. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 611–616, 1998

Synthesis of diverse ethoxyformacetal oligomers. Toward libraries of metal-coordinating unnatural biopolymers

An expedient two-step iterative protocol for the solution-phase elaboration of ethoxyformacetal oligomers is described. A set of four O,S-thioformacetal donor monomers, with diverse chiral side-chains, were coupled using NIS/TfOH activation to afford three model tetramers.

Polymerization behavior of electron‐accepting substituted quinodimethanes

AbstractThis article describes the polymerization behavior of electron‐accepting substituted quinodimethanes. Chlorine‐substituted quinodimethanes (1a–c) behave differently depending on the number of chlorine substituents. Strong electron‐accepting substituted quinodimethanes like 2a–c and 4 are not homopolymerizable, but copolymerizable with donor monomers like styrene in an alternating fashion. 7,7,8,8‐Tetrakis(alkoxycarbonyl)‐quinodimethanes (3a and 3b) and 7,7,8‐tris(tert‐butoxycarbonyl)‐8‐cyanoquinodimethane (5a) show amphoteric behavior in their alternating copolymerizations and in their charge‐transfer complex formation. Some substituted quinodimethanes with two different substituents on their exocyclic carbons (5b, 6a–c, 7a–e, 8a and 8b, and 9a–e) are homopolymerizable; for instance anionic polymerization of 7,8‐bis(butoxycarbonyl)‐7,8‐dicyanoquinodimethane (6c) takes place in a living way and gives a polymer with a molecular weight above 106. The homopolymerizations are equilibrium polymerization reactions and the thermodynamic parameters were determined. Their copolymerizations with styrene occur in a random fashion. The cross‐propagation step was studied by means of a linear free energy relationship and a new concept of radical alternating copolymerization is proposed.

Effect of Anharmonicities on the Thermodynamic Properties of the Water Dimer

A study of the effect of anharmonicities and large amplitude vibrations on the thermodynamic properties of the water dimer is presented. Different vibrational models have been constructed using ab initio data obtained at the MP2(Full)/6-311++G(2d,2p) level. In particular, we present the first complete analysis of the rotation of the hydrogen donor monomer around the O···O axis. The potential barrier was found to be 221 cm-1. A variational calculation of the torsional energy levels yields a fundamental frequency of 105 cm-1. The O···O stretching mode is described using a Morse function. The fundamental frequency and the dimerization energy are calculated to be 153 cm-1 and 5.15 kcal/mol, respectively, in agreement with the experimental results. For the dimerization reaction we have calculated ΔS, ΔH, and the equilibrium constant, Kp. The results show that inclusion of anharmonicity into the vibration modes favors the lower experimental limit for ΔS and the upper limit for ΔH. In addition, the anharmonic corrections reduce the difference between calculated and experimental Kp. This difference decreases with temperature. A high-temperature limit of 3.47 × 10-5 atm-1 was found for Kp.

Alternating terpolymerization of three non‐homopolymerizable monomers

AbstractThe free‐radical terpolymerization of maleic anhydride (MSA), isobutyl vinyl ether (VIBE) and anethol (ANE) at 60°C is described. These three monomers do not homopolymerize under the conditions used. Binary copolymers are only obtained from MSA and one of the two investigated donor monomers, whereas the binary copolymerization of VIBE with ANE is not possible. In all terpolymers from these three non‐homopolymerizable monomers the MSA content amounts to about 50 mol‐%; VIBE is about twice as reactive as ANE. The terpolymerization can formally also be described under the assumption that two binary complexes (MSA/ANE (I) and MSA/VIBE (II)) are copolymerized. For this case the reactivity ratios rI = 0,9 and rII = 1,7 are obtained.

Internal Structure of Core−Shell Latex Particles Studied by Fluorescence Nonradiative Energy Transfer

Latex particles have been synthesized in two-steps emulsion polymerizations under starving conditions, and the internal structure of these particles has been investigated by fluorescence nonradiative energy transfer (NRET), in order to check for the formation of core−shell particles. The polymers were based on methyl methacrylate (MMA) and butyl methacrylate (BMA) as monomers. The energy donor monomer was introduced during the first step of the polymerization, and the energy acceptor monomer during the second step. The Tg of PBMA is too low, compared to the polymerization temperature Tp (Tp = 80 °C), to observe a separation between the donor- and acceptor-labeled PBMA chains inside the particles. On the contrary the Tg of PMMA is larger than Tp, and a separation between energy donor- and energy acceptor-labeled PMMA chains is observed with this polymer. The separation has the structure of a diffuse interface between the two labeled PMMA polymers. The study of other particles shows that the apparent fraction of mixing, f ‘A, between donor- and acceptor-labeled polymer chains inside the particle decreases, as expected, as the incompatibility and the Tg of the polymers increase. Addition of a cross-linking agent during the first step of the polymerization leads to a decrease of f ‘A, even in the case of the PBMA latex particles. Annealing of latex films and dispersions at temperatures above the Tg of the polymers allowed phase separation or mixing inside latex particles to be observed.