Nature Of Comonomer Research Articles

PS@poly(NIPAM-co-AA) core@shell nanoparticles: size control and tuning of LCST

Here, we demonstrate a synthetic approach to precise size control of PNIPAM-based core@shell nanoparticles prepared by microemulsion polymerization as well as control of low critical solution temperature (LCST) of their water dispersions. The size of the PS-core can be tuned to ∼30 nm by a simple increase of mechanical stirring up to 1200 rpm, while the thickness of the thermoresponsive @poly(N-isopropyl acrylamide-co-acrylamide) shell can be controlled by varying the polymerization time. The effect of not only a molar ratio or co-monomer nature but also a strong influence of a thermoresponsive shell thickness on the LCST was found.

Silver nanocomposites based on water-soluble (co)polymers of 2-dialkylaminoethyl methacrylates: Kinetics of formation and pH effect

It was revealed that the neutral hydrophilic comonomer nature affects the reduction of silver ions by copolymers of 2-dimethylaminoethyl methacrylate and the formation of Ag0 nanocomposites based on them. The kinetic of silver reduction was investigated, and rate constants of pseudo first-order reactions were determined. It was shown that the rate constants increase in series 4-acryloyl morpholine <N-methyl-N-vinylacetamide < 2-deoxy-2-methacrylamido-d-glucose. The optimal molar ratio [polymer unit] : [Ag+] and polymer concentration were established. It was established that spherical silver nanoparticles have the mean radius of 7–9 nm. A decrease in the pH of aqueous dispersions of nanocomposites leads to narrowing of the surface plasmon resonance band and to shifting to shorter wavelengths. In this case, the hydrodynamic radius increases. It is assumed that the observed effect is caused both by a change in the distance between nanoparticles and by their mutual arrangement in the associate.

Polydiketopyrrolopyrroles Carrying Ethylene Glycol Substituents as Efficient Mixed Ion‐Electron Conductors for Biocompatible Organic Electrochemical Transistors

AbstractA comprehensive investigation of four polydiketopyrrolopyrroles (PDPPs) with increasing ethylene glycol (EG) content and varying nature of comonomer is presented, and guidelines for the design of efficient mixed ion‐electron conductors (MIECs) are deduced. The studies in NaCl electrolyte‐gated organic electrochemical transistors (OECTs) reveal that a high amount of EG on the DPP moiety is essential for MIEC. The PDPP containing 52 wt% EG exhibits a high volumetric capacitance of 338 F cm−3 (at 0.8 V), a high hole mobility in aqueous medium (0.13 cm2 V−1 s−1), and a μC* product of 45 F cm−1 V−1 s−1. OECTs using this polymer retain 97% of the initial drain‐current after 1200 cycles (90 min of continuous operation). In a cell growth medium, the OECT‐performance is fully maintained as in the NaCl electrolyte. In vitro cytotoxicity and cell viability assays reveal the excellent cell compatibility of these novel systems, showing no toxicity after 24 h of culture. Due to the excellent OECT performance with a considerable cycling stability for 1200 cycles and an outstanding cell compatibility, these PDPPs render themselves viable for in vitro and in vivo bioelectronics.

Antimicrobial and Drug Releasing Studies of Novel Acrylate Polymer based on Triazine

This work is focused on the synthesis and characterization of versatile acrylate polymer of chalcone based triazine for their antibacterial activity and cumulative drug release behaviour studies. The novel acrylate monomer 4-(3-(4-((4-(4-(3-(4-((7-chloroquinolin-4-yl)amino)-phenyl)-3-oxoprop-1-en-1- yl)phenoxy)-6-((4-nitrophenyl)amino)-1,3,5-triazin-2-yl)oxy)phenyl)-3-oxoprop-1-en-1- yl)phenylacrylate (SCP) is from novel chalcone and acryloyl chloride. Homo and copolymers of SCP were prepared using acrylic acid and hydroxyethyl acrylate. Physical characterization confirms the formation of the above compounds. Prepared drug molecules possess chalcone moiety as well as quinoline so it has the greater effect to inhibit the growth of the Gram-negative bacteria (15.63 ± 0.4 μg/mL) was confirmed by MIC method. The weight average molecular weight of the polymer is 10,000 g/mol. The polymer decomposes at 325 ºC. Drug releasing in vitro behaviour of the synthesized drug is controlled by the nature of comonomer, pH and the temperature.

Acrylic Acid and Methacrylic Acid Based Microgel Catalysts for Reduction of 4-Nitrophenol

N-isopropylacrylamide (NIPAM) monomer is copolymerized with acrylic acid (AA) and methacrylic acid (MAA) to synthesize poly-N-isopropylacrylamide-acrylic acid) [P(NIPAM-AA)] and poly(N-isopropylacrylamide-methacrylic acid) [P(NIPAM-MAA)] microgels. Both of these microgels possess same mol percentage of monomer and co-monomer. In order to study the influence of nature of co-monomer on size of in-situ synthesized nanoparticles, silver ions are reduced within these microgels under same conditions. The prepared samples are analyzed by Fourier transform infrared microscopy (FTIR), scanning electron microscopy (SEM), dynamic light scattering (DLS) and UV‒Vis spectroscopy. Synthesized hybrid microgels are used as catalysts for reduction of 4-nitrophenol under same conditions to investigate the influence of nature of co-monomer on apparent rate constant (kapp) of catalysis. Effect of various catalyst dosages on value of kapp is also studied. It is observed that value of kapp does not linearly increase with increase in catalyst dosage but it follows a different pattern. The dependences of dosages of both hybrid microgels on kapp are also compared. The effect of dosages of both catalysts on reaction time and catalysis duration is also studied.

High molecular weight copolymers as rheology modifier and fluid loss additive for water-based drilling fluids

In this work, the impact of molecular structure such as the degree of hydrolysis (DOH) and nature of comonomers in acrylamide-based copolymers on the rheological and filtration properties of bentonite dispersions was assessed using three different water-soluble polymers for water-based drilling fluids. These polymers are (1) copolymer of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) with 10% DOH (P1), (2) copolymer of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid (P2) with 25% DOH, and (3) copolymer of acrylamide and acrylic acid (P3) with 15% DOH. Steady shear rheology data was fitted to the Herschel-Bulkley model and flowability test was performed at 25°C and 85°C. Aging of bentonite and bentonite/polymer dispersions was performed at 90°C for 16h. Results showed that the incorporation of polymers in bentonite enhanced the filtration and rheological properties. The bentonite/P3 dispersion showed better rheological properties compared to other bentonite/polymer dispersions. The better rheological properties of bentonite/P3 dispersion suggest that acrylamide-based copolymers containing smaller comonomers such as acrylic acid are better compared to the bulky comonomers such as AMPS for drilling fluids applications. The filtration properties are less affected by the DOH and nature of comonomers, nevertheless, all polymer/bentonite dispersions showed better filtration properties compared to bentonite dispersion. The use of this high molecular weight polymer provides high thermal stability, superior rheological properties and better filtration characteristics for water-based drilling fluids.

Rheological properties of acrylonitrile—acrylamide—styrene copolymer solutions synthesized by classical and controlled radical polymerizations

The results of a comparative study of the rheological properties of acrylonitrile copolymers solutions synthesized by classical and controlled radical polymerizations in aprotic solvents (dimethyl sulfoxide, dimethylformamide, and dimethylacetamide) are presented. The influence of the chemical nature of comonomers (styrene and acrylamide) and their share in the composition of the chain on the viscosity of solutions is discussed. For all copolymers, the viscosity of solutions is determined by a product of the intrinsic viscosity per concentration. In the transition from dilute and semi-dilute solutions to the concentrated solutions, the form of the dependence changes from linear to power-law. The concentrated solutions are non-Newtonian liquids exhibiting viscoelasticity. Copolymer solutions obtained by controlled radical polymerization have a higher viscosity and less pronounced non-Newtonian behavior. The solutions of copolymers with a high comonomer content obtained in dimethylformamide have the lowest viscosity.

The Effect of Cooling Rate during Crystallization on the Melting Behavior of Polypropylenes of Different Chemical Structure

The melting behavior of polypropylenes of different chemical structure (isotactic homopolypropylene, propylene-based block and random copolymers and maleic anhydride grafted polypropylene) was studied by differential scanning calorimeter (DSC) and optical microscopy. Melting behavior and the crystal structure of polypropylene and its copolymers were observed depending on the crystallization rate, chemical nature of co-monomer unites and regularity of co-monomer units arrangement in the polypropylene main chain.

Effect of comonomer on the viscoelastic behavior of co-poly (acrylonitrile) solutions

Three copolymers of acrylonitrile-methacrylic acid [P(AN-co-MAA)], acrylonitrile-ammonium salt of methacrylic acid [P(AN-co-AMA)], acrylonitrile-methacrylamide-itaconic acid [P(AN-MAM-IA)] and PAN homopolymer were synthesized by aqueous dispersion polymerization technique. The polymerization conditions were adjusted in such a way to produce polymers with similar composition and molecular weight. The influence of comonomer nature on the viscoelastic behavior and spinnability of copolymer/dimethylsulfoxide (DMSO) solutions were investigated. It was found that incorporation of these comonomers into PAN chains led to intense decrease in zero-shear viscosity to lower value as well as appearance of distinct plateau in comparison with PAN homopolymer. However, comparing the results of complex viscosity and shear viscosity of each PAN polymer showed different shear-thinning behavior, typical deviation from Cox-Merz rule at high deformation rates. Amongst these copolymer solutions, P(AN-co-AMA) exhibited the longest relaxation time (λ) at low and medium frequencies. The lower values of frequency dependence of G′ (n′) and cross over frequency (ωc) of storage modulus (G′) and loss modulus (G″) indicated that P(AN-co-AMA) was more elastic than other PAN copolymer solutions. The log-log plots of tan δ versus ω demonstrated that the comonomer nature affects the sol-gel transition behavior and elastic character of copolymer solutions. On average, based upon the slope of logGʹ versus logGʺ data, the incorporation of comonomers inside PAN chains led to ~50 % increase in the homogeneity of solutions compared to PAN homopolymer.

Selecting the nature of imprinted molecular organosilica sieves with gallic acid via thermal analyses

The stability of the organosilica–gallic acid (GA) complex, and thus the strength of initial interactions which influences directly the sorption parameters of imprinted materials, is mostly given by the nature of co-monomers. Therefore, combining tetraethoxysilane, tetrametoxysilane, vinyl triethoxysilane and vinyl benzyl triethoxysilane as functional monomers, six formulations were obtained in order to optimise the nature of imprinted sieves. Vinyl benzyl trimethylammonium chloride and tertamethyl ammonium hydroxide directed the mesophase formation. Morphology and thermal properties of imprinted organosilica sieves were evaluated and compared to those of blank polymers synthesised in the same conditions as the imprinted ones but without GA. Thermal analysis results corroborated with the morphology of imprinted sieves were confirmed by specific GA sorption tests.

Stabilization of silver nanoparticles with copolymers of maleic acid

Silver nanoparticles are obtained by reducing AgNO3 with sodium borohydride in an aqueous solution in the presence of maleic acid copolymers with ethylene, N-vinylpyrrolidone, or styrene, as well as their octadecylamide group-containing hydrophobized derivatives, as dispersants. The influence of the structural features of the dicarboxylic acid copolymers on the silver nanoparticle formation process and the conditions for producing sols containing spherical nanoparticles with sizes of 1.5–3.5 nm (according to the data of transmission electron microscopy) are determined. It is shown that, at the equimolar copolymer/silver cation ratio, the morphology of resulting silver nanoparticles weakly depends on the nature of comonomers of maleic acid and the presence of hydrophobic fragments, which play an auxiliary role in the stabilization of dispersions of nanoparticles by increasing their stability with respect to ionic strength and oxidation. Evolution of the particle sizes in the system is monitored beginning with copolymer solutions to silver sols by the methods of light scattering, transmission electron microscopy, and atomic force microscopy. According to the light scattering data, copolymers and their complexes with silver ions in solutions are partly aggregated at concentrations corresponding to the conditions of nanosilver synthesis. Silver sols are shown to contain stabilized nanoparticles, which represent core-polyelectrolyte corona-type micelles and micellar clusters with polyelectrolyte coronas.

Luminescence of Ln3+ lanthanide complexes in polymer matrices

The photoluminescence properties of Tb3+ and Eu3+ complexes with polymer ligands containing various kinds of complexing groups—namely, carboxyl (5–20 mol %), pyridylquinoline (5 mol %), or pyridylnaphthyl (5 and 10 mol %) groups—in solution and block are considered. The chemical structure of a neutral comonomer (methyl methacrylate; styrene; isopropyl-, phenyl-, or benzylmethacrylamide; and N-vinylamides) in polymer ligands is varied. The intensity of photoluminescence is dependent not only on the chemical nature of a complexing group but also the chemical nature of a neutral comonomer and a spacer. Variation in the nature of a comonomer and a ligand makes it possible to prepare complexes in which a high luminescence of a low-molecular-mass complex is preserved and advantages inherent in a polymer complex are acquired. The effect of the nature of the polymer matrix (photoactive and photoinert) on the efficiency of electronic-excitation energy transfer is ascertained. The data on the photoluminescence of metal-polymer complexes that are based on polymer ligands containing vinylcarbozole units and that possess hole conductivity make it possible to regard them as materials for electroluminescence. The intensity of photoluminescence of these complexes is related to the competition of oppositely directed photophysical processes in a macromolecule: formation of excimers and migration of electronic excitation energy. An analysis of the published data and of the results of the authors shows that detailed studies of these polymer systems in solution and in matrices are needed to gain insight into the relationship between photo- and electroluminescence properties of metal-polymer complexes, because the matrix plays different roles in photoluminescence and electroluminescence (inner filter or conduction); as a consequence, the emission spectra may differ appreciably. It is shown that the efficiency of electroluminescence may be improved if the transfer of energy from the lanthanide ligand in a complex to the conducting matrix is decreased.

Ionomeric modification of a metallocene‐based polyolefinic elastomer and its influence on the physicomechanical properties: Effects of the crystallinity and pendent chain length

AbstractA new class of ionomer was developed through the grafting of acrylic acid onto a metallocene‐based poly(ethylene octene) elastomer, followed by its neutralization with zinc acetate. The ionomeric product was characterized through Fourier transform infrared spectroscopy, small‐angle X‐ray scattering, and transmission electron microscopy studies. The effect of the crystallinity and pendent chain length on the ionomeric modification was also studied through the variation of the level and nature of comonomer, respectively. The impact of these ionomeric modifications on various physicomechanical properties was thoroughly investigated with differential scanning calorimetry and mechanical, dynamic mechanical, and thermogravimetric analysis, and the resulting properties were correlated with the structure of the modified elastomers. The ionomerization of the base elastomers caused a significant improvement in the mechanical and thermal properties compared to the corresponding pristine elastomer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Copolymerization of propylene with higher α-olefins in the presence of the syndiospecific catalysti-Pr(Cp)(9-Flu)ZrCl2/MAO

The catalyst system i-Pr(Cp)(9-Flu)ZrCl2/methylaluminoxane was used for the synthesis of random syndiotactic copolymers of propylene with 1-hexene, 1-dodecene, and 1-octadecene as comonomers. An investigation of the microstructure by 13C NMR spectroscopy revealed that the stereoregularity of the copolymers decreased because of an increase in skipped insertions in the presence of the higher 1-olefin. The melting temperature of the copolymers, as measured by differential scanning calorimetry (DSC), decreased linearly with increasing comonomer content independently of the comonomer nature. During the DSC heating cycle, an exothermic peak indicating a crystallization process was observed. The decrease in the crystallization temperature with higher 1-olefin content, measured by crystallization analysis fractionation, indicated a small but significant dependence on the nature of the comonomer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 128–140, 2002

Polymerization and copolymerization of styrene by Ph2Zn-metallocene-MAO initiator systems.

Combined systems including diphenylzinc, Ph2Zn, a metallocene, and methylaluminoxane, MAO, have been employed to initiate styrene polymerization. These initiator systems have been also used to initiate the copolymerization of styrene with p-alkylsubstituted styrenes and with α-olefins. Both polymerization and copolymerization processes depend on the nature of the metallocene included in the initiator system, the presence of Ph2Zn, the temperature and the solvent used. Titanocenes produced syndiotactic polystyrene, s-PS, while zirconocenes gave atactic polystyrene, a-PS, with a certain content, less the 20% of s-PS. For copolymerizations the conversion to polymer was also influenced by the comonomer nature and its molar proportion in the initial feed, as well as the sort of metallocene, titanocene or zirconocene included.

Characterization of bone cements prepared with functionalized methacrylates and hydroxyapatite

Bone cements prepared with methyl methacrylate and either methacrylic acid or diethyl amino ethyl methacrylate as comonomers were characterized by infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, dynamic mechanical thermal analysis, and mechanical testing. Selected formulations containing these functionalized methacrylates were filled with hydroxyapatite and studied in terms of their properties in tension, compression and bending, and X-ray diffraction. It was found that residual monomer was not greatly affected by the presence of either acid or basic comonomers in the unfilled bone cements. In contrast, molecular weight, curing times, and glass transition temperature were composition dependent. For samples with acidic comonomer, a faster curing time, higher molecular weight, and higher glass transition temperatures were observed with respect to those with the basic comonomer. X-ray diffraction revealed that the crystalline structure was not affected by the nature of comonomer in the bone cement while scanning electron microscopy showed that hydroxyapatite remained as clusters in the bone cement.The mechanical properties of filled bone cements depended mainly on composition and type of testing. Hydroxyapatite-filled bone cements fullfilled the minimum compressive strength (70 MPa) required for bone cement use. However, the minimum tensile strength (30 MPa) was only fullfilled by cements prepared without comonomer and those containing methacrylic acid. The minimum bending strength requirement (50 MPa) was not satisfied by any of the formulations studied.

光学分割膜 感温性光学活性ポリマーによる不斉認識

This paper describes that the optically active moieties, ((S) -sec-butylacrylamide (BAAm)), in N-isopropylacrylamide (IPAAm) copolymer chains affected the phase transition behavior and resulted in lower critical solution temperature (LCST) changes responding to foreign tryptophan (Trp). Copolymerization of (S) -sec-BAAm and IPAAm were carried out in DMF at 70°C for 25 h using AIBN. The copolymer was water-soluble and showed the characteristic LCST near 27°C. LCSTs of PIPAAm chains are affected by hydrophobic or hydrophilic nature of comonomers. Since sec-BAAm is insoluble in water, the component exhibited hydrophobic property. Therefore, poly ((S) -sec-BAAm-co-IPAAm) showed lower LCST as compared with that of PIPAAm. The LCSTs of the copolymer in the presence of L-Trp weve higher than those in the absence of the amino acid. It was understood that the optically active moieties in the copolymer stereospecifically interact with L-Trp, relatively enhancing hydrophilic property of the polymer chains. The copolymer increased the LCSTs in response to increasing L-Trp concentration. Hydrogels consisting of these comonomers will exhibit reversible swelling/ deswelling behavior in response to L-amino acids such as L-Trp. The polymers with the optically active moieties demonstrate the chiral discrimination to L-amino acids and are also good candidates to perform chiral separation.

New Vistas in Synthesis of Optically Active Polymers

A rational approach has been developed for unequivocally establishing asymmetric induction in the back bone of vinyl polymers based on 1,2-disubstituted and 1-substituted olefins. Towards this end, the principle of protecting group chemistry has been utilized to connect chiral auxiliaries to functional monomers in the form of boronate esters and azomethine linkages. This approach enables to remove the auxiliaries quantitatively after polymerization. For 1,2-disubstituted olefin based systems, the role of the type of chiral auxiliary used, nature of comonomers and the location of the chiral auxiliaries with respect to the polymerizable group on enantioselectivity has been elucidated. A divinyl functional monomer bearing chiral auxiliary in the form of azomethine protecting group has been synthesized from readily accessible precursors. This monomer was found to undergo asymmetric cyclopolymerization-tion. An overview of the results obtained from these investigations is presented.

Influence of structural parameters on the dynamic mechanical properties of polyacetals

AbstractThe dynamic mechanical behaviour of various polyacetals was determined by means of torsion pendulum measurements. The products used had different structural parameters such as molecular weight distribution or comonomer nature and content, respectively; thus it was possible to investigate the influence of these parameters on the temperature dependence of the storage modulus G′, which is a measure for the rigidity of the material, and the loss tangent tan δ from ‐100 to 160°C.The storage moduli G′ are not influenced by different molecular weight distributions, but correlate with the crystallinity in the samples, which is, beside others, dependent on the concentration of the incorporated comonomer components. A decreasing crystallinity ‐ i.e. an increasing comonomer content ‐ is combined with a loss in rigidity.The distance between the peak location of the α‐relaxation in the loss tangent curves and the melting points (differential scanning calorimetry) of the investigated acetal resins is nearly constant; thus the molecular motions causing the β‐process take place in the crystalline regions. The α‐process (around −7°C) arises predominantly from molecular motions of the comonomer units, whereas the intensity of this relaxation can be correlated with the mobility of these units. The peak of the γ‐relaxation is located around −67°C and does not hardly shift despite of different structural parameters in the sample, whereas its intensity decreases with increasing both comonomer contents and contents of low‐molecular‐weight components.For unimodally distributed polyacetals with different comonomer contents, the intensity of the β‐relaxation increases with increasing comonomer contents; simultaneously the intensities of the α‐ and γ‐relaxatìon decrease.

Modifying acrylic‐based superabsorbents. I. Modification of crosslinker and comonomer nature

AbstractThis article is devoted to the synthesis, characterization, and modification of acrylic‐based superabsorbents which are synthesized by carrying out the well‐known process of inverse suspension polymerization. The dispersion is stabilized by using a mixture of micromolecular and macromolecular stabilizers. High swelling and appropriate absorption kinetics are obtained, provided that parameters (including initial monomer and crosslinker concentration, range of neutralization degree, initiating and stabilizing system, monomer addition rate, temperature and nature of the organic phase) are being considered. Modifications of crosslinker and comonomer nature and their effects on absorbency characteristics (capacity and rate) of the above‐mentioned superabsorbents are graphically presented. Finally, diffusion behavior of superabsorbents is briefly discussed. © 1994 John Wiley &amp; Sons, Inc.