Well-defined dibenzocyclooctyne end functionalized polymers from atom transfer radical polymerization

The dibenzocyclooctyne end functionalized agent 1 was designed as atom transfer radical polymerization (ATRP) initiator. The ATRP was then explored on three types of monomers widely used in free radical polymerization: methyl methacrylate, styrene, and acrylates (n-butyl acrylate and tert-butyl acrylate). The living polymerization behaviors were obtained for the methyl methacrylate and styrene monomers. The SPAAC click reactivity of dibenzocyclooctyne end group were demonstrated by successfully reacting with azide functionalized small chemical agents and polymers. Various topological polymers such as block and brush polymers were produced from strain-promoted azide-alkyne cycloaddition reaction (SPAAC) using the resultant dibenzocyclooctyne end functionalized poly(methyl methacrylate)/polystyrene as building blocks. For the acrylates, however, the polymerization did not hold the living characteristics with the dibenzocyclooctyne end functionalized ATRP initiator 1.     

Synthesis of pure (Co) polymers via supported cobalt (II)-catalyzed controlled/“living” radical polymerization

Cross-linked polyacrylic resin supported-cobalt (II) catalyst was successfully employed in controlled/“living” radical polymerization of various monomers including n-butyl acrylate (BA), ethyl methacrylate (EMA) and styrene (St). Well-defined polymers with predetermined molecular weight and relatively narrow molecular weight distribution were synthesized. After polymerization, the supported cobalt (II) catalyst was easily and effectively removed from the polymerization system by simple centrifugation and very pure polymer products were obtained (Co residue <0.1 ppm). Using the obtained polymers as macroinitiators, polymerization of methyl methacrylate (MMA) and fluorinated methacrylate ether 2-[(perfluorononenyl)oxyl] ethyl methacrylate (FNEMA) were performed, respectively. Well-defined and pure diblock copolymers PBA-b-PMMA, PS-b-PMMA and PS-b-PFNEMA were synthesized.     

A novel method for preparing poly(alkyl methacrylates) and poly(methacrylic acids) of varying tacticity

In order to synthesize poly(methacrylic acid) and poly(alkyl methacrylates) over a wide range of polymer tacticity, the anionic polymerization of the following alkyl methacrylates (ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-amyl, n-hexyl, n-octyl, n-decyl, n-lauryl, and n-octadecyl) in toluene using phenylmagnesium bromide initiation was studied. It was found that the amount of isotactic polymer structure generally decreased as the size of the ester group increased. In all cases, the polymers had greater than 50% isotactic triad structure. Whether the polymerization was carried out at 0° or ?78°C had little or no effect on the tacticity of the polymer produced. It was found that the poly(alkyl methacrylates) produced could be hydrolyzed in concentrated sulfuric acid to poly(methacrylic acid). The poly(methacrylic acid) produced in the hydrolysis could be esterified with diazomethane to give poly(methyl methacrylate) or with diazoethane to give poly(ethyl methacrylate) with the same tacticity as the poly(alkyl methacrylate) from which the poly(methacrylic acid) was derived. It is possible, therefore, to produce poly(alkyl methacrylates) of a desired tacticity by polymerizing the appropriate monomer, hydrolyzing, and reesterifying the resultant poly(methacrylic acid) with a diazoalkane to give the desired poly(alkyl methacrylate).     

Thermal behavior of graft copolymers of cotton cellulose and acrylate monomers

Cotton cellulose yarn was grafted with methyl acrylate, ethyl acrylate, n-butyl acrylate, and methyl methacrylate at various percentages of grafting. The effects of concentration of the initiator, concentration of the acid, and of temperature on grafting was studied and the mechanism discussed. The effect of reactivity of the monomer on the percentage graft-on is pointed out. Thermal behavior of natural and grafted cotton yarn was studied using dynamic thermogravimetry in air at a heating rate of 6°C/min up to a temperature of 500°C. The thermal stabilities of the samples grafted with various acrylate monomers to various percentages of grafting were computed from their primary thermograms by calculating the values of IDT, IPDT, and E^*. The results show that the thermal stability increases with increase in graft-on per cent, and the thermal stabilities of natural cotton and cotton grafted with different monomers are in the order ethyl > methyl > natural cellulose > methyl methacrylate > n-butyl acrylate.     

Grafting of formaldehyde-crosslinked and cyanoethylated cotton cellulose with acrylate monomers

Formaldehyde-crosslinked cotton and cyanoethylated cotton were grafted with methyl, ethyl, and n-butyl acrylates and methyl methacrylate using ceric ion as initiator. It was observed that the graft yields for formaldehyde-crosslinked cotton were significantly higher than those for native cotton. An increase in the bound formaldehyde resulted initially in a decrease in molecular weight of grafts; but later on, an increase was observed. In the case of cyanoethylated cottons, increasing the degree of substitution resulted in increase in graft yields. Molecular weights of the grafts increase up to a D.S. of 0.3, after which they decrease. These results are interpreted in terms of rates of initiation and termination being influenced by production of additional sites due to swelling of cellulose fibers.     

Studies on IPNS based on nitrile rubber and polyalkyl methacrylates

Sequential interpenetrating polymer networks (IPNs) based on nitrile rubber and various types of polyalkyl methacrylates such as poly(n-butyl methacrylate), poly(ethyl methacrylate), and poly(methyl methacrylate) were synthesized. The compositions of the IPNs could be varied by varying the reaction parameters such as swelling time and concentration of crosslinker. The tensile properties of the IPNs show that with increase in bulkiness of the ester group of the acrylates the tensile strength decreases, whereas elongation at break increases because of decreased stiffness of the acrylate phase. The dynamic modulus and loss tangent of the IPNs also show similar trend because of the above reason. All the IPNs were also tested for dynamic properties under multifrequency mode, and with the help of the WLF equation, the behavior of these IPNs in the frequency range of 1–10⁵ Hz were evaluated. The results showed reasonably high tan δ with good storage modulus in the entire frequency range for all the IPNs. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:549–554, 1997     

Modification of polyvinyl chloride-vinyl acetate latex by seed emulsion polymerization of acrylic monomers

Fundamental studies were carried out to modify the thermal properties of polyvinyl chloride (PVC)-based latices. General features of composite PVC-vinyl acetate (VAc) copolymer latices synthesized from the seed emulsion polymerization of acrylic monomers are reported, in particular, the observation of particle morphology and the measurements of minimum film formation temperature (MFT) and DSC spectra. Acrylic monomers used as modifiers were methyl methacrylate (MMA), n-butyl methacrylate (BMA), methyl acrylate (MA), ethyl acrylate (EA), n-butyl acrylate (nBA), and MMA-nBA 75:25,50:50 and 25:75 wt%. Styrene whose polymer is incompatible with PVC-VAc was used as a counterpart of compatible PMMA. Compatibility between seed and modifier polymer and the mode of operation, either batch (flooded and pre-swollen) or semi-batch (starved and no swelling), induced morphology differences, and consequently variations of thermal properties.     

Detection and quantification of branching in polyacrylates by size-exclusion chromatography (SEC) and melt-state C NMR spectroscopy

Chain branching has been investigated in a homologous series of poly(n-alkyl acrylates) (methyl, ethyl, n-butyl, n-hexyl) obtained by radical polymerization. The total amount of chain branching was quantified using melt-state ¹³C nuclear magnetic resonance (NMR) spectroscopy. It gave access to low degrees of branching in both soluble and insoluble polyacrylates, homopolymers and copolymers. The lowest degree of branching was found for the ethyl member of the series with quantification by conventional solution-state NMR found to take a prohibitively long time. The method proposed here is compared to the ones published previously, and previous literature results are critically reviewed.The presence of long-chain branching (LCB) was selectively detected using multiple-detection size-exclusion chromatography (SEC), with LCB being found for all soluble homopolymers but the poly(n-butyl acrylate). This finding was confirmed by close examination of the Mark-Houwink parameters for the various polyacrylates studied in this work or those previously published.     

Seeded emulsion terpolymerization of dimethyl meta-isopropenyl benzyl isocyanate (TMI®) with acrylic monomers

Dimethyl meta-isopropenyl benzyl isocyanate (TMI®) is a novel bifunctional monomer. It has a double bond and an isocyanate group. The seeded emulsion terpolymerization of TMI with the acrylic monomers, methyl methacrylate and n-butyl acrylate, has been studied. A copolymer of methyl methacrylate and n-butyl acrylate was used as the seed latex. In order to minimize the risk of hydrolysis of TMI, polymerizations were carried out at 40°C using redox initiators. No additional surfactant was added during the second-stage polymerization in order to avoid the nucleation of secondary particles. TMI was found to retard the polymerization kinetics. The effect of variables, such as the total number of particles, initiator concentration, and the monomer feed rate on polymerization kinetics, was investigated. The composition of the second-stage polymer could be controlled by running the polymerization under monomer-starved conditions. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 685–694, 1998     

Polymer-leather composites. I. Process and location study for the deposition of selected acrylate monomers by polymerization into chrome-tanned cattlehide

Three acrylate monomer systems were deposited by redox emulsion polymerization at room temperature into the fibrous matrix of 2-mm-thick chrome-tanned cattlehide over a wide range of composition. Polymer not bound to the matrix was separated by hot benzene extractions. Monomers used were methyl methacrylate, a mixture of n-butyl acrylate and methyl methacrylate and n-butyl acrylate, each selected to produce composites having wide variation in glass-transition temperature. The same three systems were introduced into the free space of leather by bulk and solution polymerization. All conversions were close to 100%. When the emulsion technique was used, with feed composition variable, overall deposition efficiency depended on the characteristic rate of deposition for the individual acrylate monomers. Observed orders in deposition rate and overall efficiency were: methyl methacrylate > comonomer > n-butyl acrylate. However, specific deposition efficiencies declined roughly monotonically with feed or time increase, but maintained the same order. Microscopic examination of thin sections revealed polymer only in the outer region of the leather cross section. Information on polymer location and its influence on specimen thickness for composites prepared by both emulsion and solution methods of deposition were obtained by correlating experimental densities with theoretical density–composition curves for various assumed models. The foregoing, together with observations of greatly reduced grafting frequency, in view of the maximum theoretically attainable, made a dominant grafting mechanism unattractive. A mechanism involving diffusion controlled monomer transport to occluded radicals in localized polymer deposits was suggested as an alternative.     

Studies in radiation-induced polymerization of vinyl monomers at high dose rates. II. Methyl methacrylate

The radiation-induced polymerization of methyl methacrylate was investigated with radiation sources of cobalt 60 and accelerated electrons at dose rates up to 3 Mrads/sec. Extrapolation of previous rates of polymerization at dose rates of 0.01–200 rads/sec coincided with the present results, the rates being approximately proportional to the square root of the dose rate throughout the entire set of dose rates measured. The molecular weights seemed to be independent of dose rate at the highest dose rates investigated. A combination of high polymer with a much higher molecular weight than expected was formed, together with a substantial portion of low molecular weight polymer. The reason for this behavior is not clear at this time. The G(M·) calculated from the molecular weights and fraction of polymer and resin was 6.0, which approaches that reported in previous investigations at low dose rates. There was no significant effect of air on the polymerization kinetics of methyl methacrylate at above 1 Mrad/sec. Nitrogen also did not influence the measured rates. Conversions to polymer were not substantially reduced by the presence of inhibitor at above 1.26 × 10⁵ rads/sec. Water did not influence the rates of polymerization, except at the highest temperature (50°C) investigated. A large posteffect was observed in sealed degassed ampoules after 25% conversion to polymer. Only 3.4% additional polymer was formed in 24 hr after irradiation in the presence of air. The activation energy for the electron beam polymerization of methyl methacrylate was about 7.0 kcal/mole. This value, considering the complications in technique such as beam heating, did not differ from literature data enough to suggest any mechanistic difference in the polymerization at high dose rates.     

Synthesis,characterization, and thermal behavior study of methyl methacrylate polymers containing 4‐carbazole substitutes

A new polymerizable monomer, [4‐(9‐ethyl)carbazolyl]methyl methacrylate ( 2 ), was synthesized by reacting of methacrylic acid and 4‐hydroxymethyl‐9‐ethyl carbazole ( 1 ) by esterification procedure in the presence of N,N′‐dicyclohexylcarbodiimide. The resulting monomer was then polymerized free‐radically to form the poly(methyl methacrylate) containing 4‐(9‐ethyl)carbazolyl pend ent groups. Also, copolymerization of monomer 2 with various acrylic monomers such as methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, and n‐butyl acrylate by azobisisobutyronitrile as a free radical polymerization initiator gave the related copolymers in high yields. The structure of all the resulted compounds was characterized and confirmed by FTIR and ¹H NMR spectroscopic techniques. The average molecular weight of the obtained polymers was determined by gel permeation chromatography using tetrahydrofurane as the solvent. The thermal gravimetric analysis and differential scanning calorimeter instruments were used for studying of thermal properties of polymers. It was found that, with the incorporation of bulky 4‐(9‐ethyl)carbazolyl substitutes in side chains of methyl methacrylate polymers, thermal stability and glass transition temperature of polymers are increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4989–4995, 2006     

Mechanism of the polymerization of n-butyl acrylate initiated by N,N-diethyldithiocarbamate derivatives. Part 2. Investigation of the reaction mechanism

The polymerization of n-butyl acrylate (BuAc) initiated with a model compound (butyl-2-(N,N-diethyldithiocarbamyl)propionate, RTC) has been investigated. The living character of this polymerization has been assessed and compared with those of styrene and methyl methacrylate. The small variation of M_n with yield is explained by the faster propagation than for styrene and methyl methacrylate, which leads to slow initiation and extensive transfer to the initiator. Predominant reversible termination (or deactivation) of the growing chains by the dithiocarbamyl radicals gives, however, polymers of functionality near to unity, which are photoinitiated at the same rate as RTC and reinitiate the polymerization of BuAc with a linear growth of the M_n up to 40% yield. This is better than was obtained with methyl methacrylate. Side reactions also take place leading to a decrease of functionality, to the formation of tetraethylthiuram disulphide and of carbon disulphide. Possible mechanisms are proposed for the secondary reactions. © 1998 SCI.     

Influence of steric length in electrosteric surfactants on emulsion polymerization

Four PPG Avanel Series S surfactants (sodium alkyl polyether sulfonates) with varying ethylene oxide content (n = 3, 7, 9, and 15) were used to investigate the influence of the steric length in this type of electrosteric stabilizers on emulsion polymerization. The polymerization studies employing potassium persulfate as an initiator with styrene, methyl methacrylate, and vinyl acetate monomers showed no apparent change in particle size, number of particles, and polymerization rate with the changing steric length of the surfactant. Steric influences were observed in the redox-initiated systems of styrene, butyl acrylate, and methyl methacrylate. Increasing the ethylene oxide unit content from three to nine units decreased the rate of polymerization, the particle size and number in the polystyrene latexes. Polymerizations with the acrylates displayed the same trend except that the polymerization rate reached a minimum value at nine ethylene oxide units and increased when the surfactant containing 15 ethylene oxide units was used.     

Co γ-Initiated polymerization of vinyl monomers in room temperature ionic liquid/THF mixed solutions

Radiation induced polymerization of styrene (St), methyl methacrylate (MMA) and n-butyl methacrylate (BMA) is carried out in a room temperature ionic liquid (RTIL), [Me₃NC₂H₄OH]⁺[ZnCl₃]⁻, and in its mixed solutions with THF. The presence of ionic liquid (IL) leads to a significant increase in monomer conversion and polymer's molecular weight. Molecular weight distribution (MWD) of resulting polymer varies with the IL fraction in the RTIL/THF solutions and is also dependent on the monomer used. For polystyrene (PSt) and poly(n-butyl methacrylate) (PBMA), multi-modal broad MWD is observed at IL >50 v% while single-modal narrow MWD is observed at IL <40 v%. For poly(methyl methacrylate) (PMMA), however, nearly a single-modal MWD is observed at THF >20 v%. The measured miscibility of polymer with RTIL is in the order: PMMA>PBMA>PSt. Here we propose that the difference in MWD is due to the inhomogeneous nature of the ionic liquid in micro-region and the immiscibility of polymer with medium.     

Polymeric Linoleic Acid–Polyolefin Conjugates: Cell Adhesion and Biocompatibility

To diversify edible-oil polymer composite, polymeric linoleic acid (PLina) peroxide was obtained by the auto-oxidation of linoleic acid in a simple way for use as a macroinitiator in free radical polymerization of vinyl monomers. Peroxidation, epoxidation, and/or perepoxidation reactions of linoleic acid under air at room temperature resulted in PLina, having soluble fraction more than 91 weight percent (wt%), with molecular weight ranging from 1,644 to 2,763 Da, and containing up to 1.0 wt% of peroxide. PLina initiated the free radical polymerization of ether styrene (S), methyl methacrylate (MMA), or n-butyl methacrylate (nBMA) to give PLina-g-polystyrene (PS), PLina-g-poly-MMA (PMMA), and PLina-g-poly- nBMA (PnBMA) graft copolymers. The polymers obtained were characterized by proton nuclear magnetic resonance (¹H NMR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC) techniques. Microstructure of the graft copolymers was observed by using scanning electron microscope (SEM). Graft copolymers obtained contained polymeric linoleic acid in a range between 8.5 and 19.3 mol percent (mol%). PLina-g-PS, PLina-g-PMMA and PLina-g-PnBMA graft copolymer samples were also used in cell culture studies. Fibroblast and macrophage cells were strongly adhered and spread on the copolymer film surfaces. These newly synthesized copolymers were tested for their effects on human blood protein adsorption compared with PMMA graft copolymers containing polymeric soybean oil and polymeric linseed oil; interestingly we observed a dramatic decrease in the protein adsorption on the linoleic acid graft copolymer, which is important in tissue engineering.     

Photoinduced controlled/“living” polymerization of methyl methacrylate with flavone as photoinitiator

Photochemically mediated controlled/“living” polymerization of methyl methacrylate (MMA) triggered by flavone was studied. The polymerization was performed in ethanol at ambient temperature with CuBr₂/Tris(2‐dimethylaminoethyl)amine (Me₆TREN) as complex catalyst and ethyl 2‐bromoisobutyrate (EBiB) as initiator. The molar mass of poly(methyl methacrylate) (PMMA) was obtained and exhibited relatively narrow molecular weight distribution (M_w/M_n) which was characterized by gel permeation chromatography (GPC). Chain extension further indicated that the living nature was maintained in the photopolymerization system. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43845.     

Homopolymer of 4-chloro-3-methyl Phenyl Methacrylate and its Copolymers with Butyl Methacrylate: Synthesis, Characterization, Reactivity Ratios and Antimicrobial Activity

The methacrylate monomer 4-chloro-3‐methyl phenyl methacrylate (CMPM) was synthesized by reacting 4-chloro-3‐methyl phenol with methacryloyl chloride. The homopolymer and various copolymers of CMPM with n-butyl methacrylate were synthesized by free-radical polymerization in toluene at 70°C using 2,2′-azobis(isobutyronitrile) as the initiator. The CMPM monomer was characterized by Fourier transform IR and ¹H-NMR studies. The copolymers were characterized by IR spectroscopy. The molecular weights (M _n and M _w) and the polydispersity index were obtained from gel permeation chromatography. The solubility and intrinsic viscosity of the homopolymer and the copolymers are also discussed here. The copolymer composition obtained from UV spectra led to the determination of reactivity ratios employing Fineman-Ross and Kelen-Tudos linearization methods. Thermogravimetric analyses of the homopolymer and the copolymers were carried out under a nitrogen atmosphere. The homopolymer and the copolymers prepared were tested for their antimicrobial activity against bacteria, fungi and yeasts.     

Preparation of functional poly(acrylates and methacrylates) and block copolymers formation based on polystyrene macroinitiator by ATRP

The polymerization by ATRP of hydroxy and amino functional acrylates and methacrylates with tert-butyldimethylsilyl (TBDMS) or tert-butyloxycarbonyl (BOC) protective groups has been studied for the first time achieving high control over molecular weight and polydispersity. Detailed investigation of the ATRP of 2-{[tert-butyl(dimethyl)silyl]oxy}ethyl acrylate (M2b) in bulk and 2-[(tert-butoxycarbonyl)amino]ethyl 2-methylacrylate (M3a) in diphenyl ether (DPE) showed that the type of ligand plays an important role on either the polymerization rate or the degree of control of the polymerization. Among the ligands used, N,N,N,′N″N″-pentamethyl diethylenetriamine (PMDETA) was the most suitable ligand for ATRP of all functional acrylates and methacrylates. The kinetics of M2b and M3a polymerization using PMDETA as a ligand was reported and proved the living character of the polymerization. Well-defined block copolymers based on a halogen terminated polystyrene (Pst) macroinitiator and the functional acrylate and methacrylate monomers were successfully synthesized by ATRP, and subsequent deprotection of the protective groups from the acrylate or methacrylate segment afforded amphiphilic block copolymers with a specific solubility behavior.     

Controlled radical polymerization with polyolefin macroinitiator: a convenient and versatile approach to polyolefin-based block and graft copolymers

This paper introduces the new synthetic methodology of polyolefin-based block and graft copolymers with polar segments [e.g., polystyrene and poly(meth)acrylates]. Various brominated polyolefins were prepared by bromination of polyolefins with N-bromosuccinimide. The resulting brominated polyolefins were able to initiate the controlled radical polymerization of polar monomers, such as methyl methacrylate, ethyl acrylate, t-butyl acrylate, styrene and 2-(dimethylamino)ethyl acrylate, using a CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine catalyst system, leading to a variety of polyolefin-based copolymers with a different content of the corresponding polar segment. Because of the accessible synthesis of polyolefin macroinitiators, this synthetic methodology is expected to result in the preparation of a wide range of polyolefin-based block and graft copolymers.