High Molecular Weight Copolymers Research Articles

Polyacrylamides bearing pendant alpha-sialoside groups strongly inhibit agglutination of erythrocytes by influenza A virus: multivalency and steric stabilization of particulate biological systems.

An alpha-sialoside linked to acrylamide by a short connector (5-acetamido-2-O-(N-acryloyl-8-amino-5-oxaoctyl)-2,6-anhydro-3,5-d ideoxy-D-galacto-alpha-nonulopyranosonoic acid, 1) was prepared. Compound 1 formed high molecular weight copolymers with acrylamide, derivatives of acrylamide, and/or vinylpyrrolidone upon photochemically-initiated free radical polymerization. Those copolymers for which the substituents on the acrylamido nitrogen were small inhibited the agglutination of chicken erythrocytes induced by influenza virus (X-31 (H3N2); a recombinant strain of A/Aichi/2/68 (H3N2) and A/Puerto Rico/8/34 grown in chicken eggs). The inhibitory power of the polymers depended strongly on the conditions of polymerization and the sialic acid content of the polymer. The strongest inhibitors were copolymers (poly(1-co-acrylamide)) formed from mixtures of monomer containing [1]/([1] + [acrylamide]) approximately 0.2-0.7; these copolymers inhibited hemagglutination 10(4)-10(5) times more strongly than did similar concentrations of alpha-methyl sialoside (calculated on the basis of the total concentration of individual sialic acid groups in the solution, whether attached to polymer or present as monomers). Samples polymerized in the presence of low concentrations of cross-linking reagents (bis(acrylamido)methane, BIS, and 2,2'-bis(acrylamido)ethyl disulfide, BAC) also showed increased inhibition (10-10(3)-fold relative to monomers), but their use was limited by their poor solubility. Sterically demanding substituents on any position of the acrylamide component (substituents attached to the vinyl group or N-alkyl groups that are larger than hydroxyethyl) reduced the inhibitory power of the polymer. A 1H NMR assay and a fluorescence depolarization assay showed that poly(1-co-acrylamide) bound to a solubilized trimeric form of the viral receptor for sialic acid (bromelain cleaved hemagglutinin, BHA), less tightly than 1, on a per sialic acid basis. A similar result was also obtained with a model system comprising lactic dehydrogenase (a tetramer) and polymeric derivatives of oxamic acid: that is, poly((28, 29, 30, or 31)-co-acrylamide) had a higher inhibition constant for tetrameric lactic dehydrogenase than did the corresponding monomers (28, 29, 30, or 31) on a per oxamate basis. Poly(1-co-acrylamide) is, in principle, capable of inhibiting the agglutination of erythrocytes by several mechanisms: (1) entropically enhanced binding of the polymer (acting as a polyvalent inhibitor) to the surface of the virus; (2) steric interference of the approach of the virus to the surface of the erythrocyte by a water-swollen layer of the polymer on the surface of the virus; (3) aggregation of the virus induced by the polymer.(ABSTRACT TRUNCATED AT 400 WORDS)

Synthesis and Characterization of Triphenylphosphine Oxide-Containing Poly(Aryl Imide)-Poly(Dimethyl Siloxane) Randomly Segmented Copolymers

Abstract Poly(aryl imide)-poly(dimethyl siloxane) randomly segmented copolymers were synthesized by essentially a one-step solution imidization process in a solvent system consisting of predominately o-dichlorobenzene with a small amount of n-methylpyrolidone. This solvent combination was selected because of its ability to afford homogeneous solutions throughout the polymerization process. This enabled copolymers of any desired poly(dimethyl siloxane) composition to be prepared. A hydrolytically stable triphenylphosphine oxide containing diamine, bis(3-amino-phenoxy-4′-phenyl)phenylphosphine oxide, was utilized as a chain extender and together with oxydiphthalic anhydride formed the hard segment in these copolymers. The soft segment was formed from α,ω-aminopropyl poly(dimethyl siloxane) oligomers of controlled molecular weight. The presence of phosphorus and silicon contributes several unique properties to the system, including enhanced solubility, thermal stability, and flame resistance. High molecular weight copolymers containing up to 60% (w/w) of the poly(dimethyl siloxane) segments were successfully prepared using this method. Gel permeation chromatography analysis, based on a universal calibration curve in CHCl3, was performed to determine the molecular weights and distribution. These copolymers with 40-60% (w/w) poly(dimethyl siloxane) exhibited upper Tg values ranging from 130 to 180°C and showed substantial char yields at 750°C in air, which increased with siloxane content. Dynamic mechanical analysis confirmed the anticipated microphase behavior by the presence of two separate glass-transition regions. Both small angle x-ray scattering and transmission electron microscopy measurements determined on well-characterized transparent cast films were used to better demonstrate the multiphase nature of these copolymers.

Pseudo-ladder rigid-rod polymers: dihydroxy pendent benzothiazole aromatic heterocyclic polymer and copolymers

Anisotropic homopolymerization of 2,5-dihydroxyterephthalic acid (DHTA) and 2,5-diamino-1,4-benzenedithiol dihydrochloride (DABDT.2HCl), and copolymerization of DHTA, terephthalic acid and DABDT.2HCl in polyphosphoric acid (PPA), afforded high molecular weight rigid-rod polymer and copolymers, with two hydroxyl groups as pendants per repeat unit. In PPA, the lyotropic liquid crystalline behaviour of the homopolymer was distinctly affected by the polymerization temperature. Spectroscopic evidence strongly suggested a completely planar and ribbon-like structure, the consequence of the strong intramolecular hydrogen bonds between the OH moieties and the N atoms of the nearby benzothiazole units. The homopolymer also exhibited the unusual capability, characteristic of BBL-type ladder polymers, to form directly from its precipitate an aggregated film which displayed little or no shrinkage when dried. Anisotropic dopes of the homopolymer (dihydroxy-polybenzothiazole (PBZT)) and certain dihydroxy-PBZT/PBZT copolymers were spun into fibres with typical tensile properties for modified PBZT polymers, but marginal compressive strength (4–30 ksi (1 ksi = 6.9 MPa) for homopolymer and 16–61 ksi for the copolymers). The intrinsic conductivity for the as-spun fibre of the homopolymer was 2.2 × 10 −7 S cm −1 and that for heat-treated (435°C) fibre was 5.6 × 10 −8 S cm −1.

Potentiometric titration of acrylamide-acrylic acid copolymers: Influence of the concentration

Potentiometric titrations of acrylamide-acrylic acid copolymers of high molecular weight were made at various polymer concentrations, C p, and ionic strengths, I. At a given pH, the ionization degree of the carboxylate groups is found to increase when C p and I increase. In the absence of salt and for a fraction τ of acrylic units in the polymer, the values of p K a at different C p lie on a single curve as a function of ( ∞C p − 1 3 ) for a given τ. It is found that p K a obtained for the various values of C p is a polynomial function of τ 1 2 C p − 1 3 .

Formulation and polymerization of microemulsions containing a mixture of cationic and anionic monomers

A series of polyampholytes of sodium-2-acrylamido-2-methylpropanesulfonate (NaAMPS) and 2-(methacryloyloxy) ethyltrimethylammonium chloride (MADQUAT) has been synthesized by free radical polymerization in microemulsions. The optimization of the formulation was, by a selection procedure, based on the hydrophile-lipophile balance (HLB) of the nonionic surfactants and solubility parameters of the different components. Both ionomers play an important role in the formulation owing to their amphiphilic and electrolyte characters as confirmed by surface tension and turbidimetry experiments. These effects control the HLB and interfacial properties of the microemulsions. The results are semi-quantitatively interpreted from the cohesive energy ratio (CER) concept. The reaction products are stable inverse latexes consisting of high molecular weight copolymers entrapped in water droplets particles and dispersed in an isoparaffinic oil.

Processible poly(arylene ether ketones) that can be crosslinked to high-performance networks

High molecular weight copolymers containing 2,5-bis(4-fluorobenzoyl)benzocyclobutene (BFBCB),1,4-bis(4-fluorobenzoyl)benzene (BFB), and 4,4-isopropylidenediphenol have been synthesized by solution polycondensation. Soluble, amorphous polymers were obtained and no evidence of cross-linking occurred during the polumerization reaction, provided that the temperature was maintained below 150°C. The polymers can be cross-linked well above their T g by brief treatment in nitrogen at 400°C. The resulting networks are insoluble in all solvents. No significant mass loss accompanies the cross-linking reaction

Radical polymerization of styrene initiated by poly(ethylene oxide) macroinitiators

Segmented poly(ethylene oxide) macroinitiators containing bistrialkylbenzopinacolate groups were used to initiate radical polymerization of styrene. A polystyrene-PEO block copolymer is formed by the incorporation of the PEO macroinitiator. The PEO fraction in the copolymer decreases with increasing polymerization yields. Since the molecular weight of the macroinitiator is low, the incorporated PEO fraction is necessarily small in high molecular weight copolymers.

New main chain nonlinear optical polymers with high glass transition temperatures

Various 4-methoxy-4′-carbomethoxy-α-amino-α′-cyanostilbenes were prepared as mixtures of E and Z isomers, and polymerized via condensation polymerization using dibutyltin diacetate as catalyst. The resulting low molecular weight homopolymers showed higher glass transition temperatures (168–183°C) than previously reported main chain nonlinear optical (NLO) homopolymers. A high molecular weight (Mn≃30, 200) copolymer possessed an even higher glass transition temperature of 187°C. The hyperpolarizability of the polymers and a model compound were found by EFISH measurements to be in the range of 61 to 79x10-48 esu.

N-Acryloyl-o-aminobenzoic Acid and Styrene Copolymer-III. Application of Different Methods for Intrinsic Viscosity and Viscosity Constant Determination

A high molecular weight copolymer of N-acryloyl-o-aminobenzoic acid (OAB) and styrene has been prepared by radical polymerization using benzoyl peroxide initiator in dioxane solvent. The copolymer has been fractionated by fractional precipitation and the fractions characterized by viscometry, vapour pressure osmometry and gel permeation chromatography. Mark-Houwink-Kuhn-Sakurada (MHKS) relationships are developed for three different solvents. Both the intrinsic viscosities and the viscosity constants of eight PO-PS fractions were obtained by the Huggins, Kraemer, Martin and Schulz-Blaschke methods in dimethyl formnamide, toluene and tetrahydrofuran solvents. It was concluded that the values obtained by these four methods are in close agreement.

Synthesis and properties of polyampholytes prepared in microemulsions

A series of polyampholytes of sodium 2-acrylamido-2-methylpropanesulfonate (NaAMPS) and 2-(methacryloyloxy)ethyltrimethylammonium chloride (MADQUAT) has been synthesized by polymerization in microemulsions. The reaction products are stable inverse latexes consisting of high molecular weight copolymers entrapped in water droplets of small size (d % 80 nm) and dispersed in an isoparaffinic oil. The optimization of the formulation was by a selection procedure based on the hydrophile-lipophile balance of the emulsifiers and solubility parameters of the different components. Both ionomers play an important role in the formulation owing to their amphiphilic and electrolyte characters. Reactivity parameter studies yield rA and rM values of 0.81 and 1.97 for NaAMPS and MADQUAT, respectively. The properties of polyampholytes in pure water and in salt solutions were investigated by turbidimetry and viscometry experiments. The results are compared with the recently developed theory of Higgs and Joanny (J. Chem. Phys. 94, 1543 (1991)).

Polymers for biodegradable medical devices. IX: Microencapsulation studies; effects of polymer composition and process parameters on poly-hydroxybutyrate-hydroxyvalerate microcapsule morphology.

Reservoir-type microcapsules were prepared using a double emulsion solvent evaporation technique from a series of nine different poly-beta-hydroxybutyrate (PHB)-based polymers in which both molecular weight and hydroxyvalerate content were varied. Particles prepared from a low molecular weight (MW 43,000) homopolymer had a shrivelled appearance, but were not porous. When the molecular weight of the fabricating homopolymer was increased to 540,000, however, these features disappeared and non-wrinkled particles with microporous surfaces were observed. Microcapsules prepared from a high molecular weight copolymer of PHB with 10.8 per cent hydroxyvalerate (HV) had a similar appearance, but particles prepared from a high molecular weight 20.1 per cent HV copolymer had much smoother and less porous surfaces. Lowering the molecular weight of the copolymer had the effect of producing particles that were generally distorted in shape and had highly irregular, macroporous, surface morphologies. Increasing the double emulsion temperature to 40 degrees C at 2 min after phase combination typically generated smoother and/or less porous particles and improved the batch yield. The numerous factors potentially responsible for the development of morphological characteristics of the products are discussed in the light of these observations.

Synthesis and Characterization of Thermotropic Polyethers Based on 4,4′-dihydroxy-α-methylstilbene and Flexible Spacers Containing Even Numbers of Methylene Units and Copolyethers Based on Pairs of Flexible Spacers Containing Even and Odd-Even Numbers of Methylene Units

Abstract This paper describes the synthesis and characterization of thermotropic polyethers based on 4,4′-dihydroxy-α-methylstilbene (HMS) and flexible spacers containing an even number of methylene units and copolyethers based on 4,4′-dihydroxy-α-methylstilbene (HMS) and flexible spacers containing even-even and even-odd numbers of methylene units [i.e., HMS-X/Y(A/B), where X and Y refer to the number of methylene units in the first and second spacer, and A/B refers to the molar ratio between the two spacers]. The following polyethers and copolyethers were synthesized and characterized: HMS-6, HMS-8, HMS-10, HMS-12, HMS-6/8(A/B), HMS-6/10(A/B), HMS-6/12(A/B), HMS-8/10(A/B), HMS-8/12(A/B), HMS-10/12(A/B), HMS-6/7(A/B), HMS-6/9(A/B), HMS-7/10(A/B), HMS-8/ll(A/B), HMS-7/12(A/B), and HMS-9/12(A/B). Due to their low solubility, both homopolymers and copolymers based on even-even combinations of flexible spacers were obtained with low molecular weights. High molecular weight copolymers were obtained only when ...

High molecular weight copolymers of l-lactide and ?-caprolactone as biodegradable elastomeric implant materials

High molecular weight copolymers of L-lactide and e-caprolactone have been synthesized by ring opening copolymerization with stannous octoate as catalyst. The good mechanical properties of the 50/50 copolymers make it a suitable material for biomedical applications such as nerve guides etc., where degradation of the elastomeric implant is required. In contrast to the frequently used MDI containing polyurethanes, degradation products of the P(LLA-e-CL) are non toxic. The use of such a material is therefore preferable.

A comparison of the E-beam sensitivities and relative O 2-plasma stabilities of organosilicon polymers.Part III. Lithographic characteristics of poly-1,1,3-trimethyl-1-sila - and poly-1,1,3,3-tetramethyl-1,3- disilacyclobutenes and related silmethylene polymers

The electron beam sensitivities of three different types of high molecular weight polysilmethylene polymers and copolymers were investigated. It was found that methyl derivatives of these polymers have high sensitivities to irradiation and have a negative tone. The influence of the molecular weight upon electron beam sensitivity was also investigated. In contrast to polysiloxanes, phenyl containing polysilmethylenes were found to have a much higher sensitivity (up to 10 ¢c for poly-1,1-diphenyl- 1-silacyclobutane) and comparable thermal stabilities (up to 400°C). It was found that some of these polymers have similar lithographic properties to the more common polysiloxanes. Mechanisms of crosslinking and degradation reactions of these polymers are discussed.

Copolymerization of 2‐methylene‐4‐phenyl‐1,3‐dioxolane with electrophilic vinyl monomers through zwitterionic mechanism

AbstractSpontaneous copolymerization of cyclic ketene acetal, 2‐methylene‐4‐phenyl‐1,3‐dioxolane (I) with common electrophilic vinyl monomers, such as methyl α‐cyanoacrylate (MCA), acrylonitrile (AN), and methyl methacrylate (MMA) were investigated to further explore zwitterion polymerization method with cyclic ketene acetals. In the reaction of I with MCA and AN, spontaneous copolymerization took place at ambient temperature. The copolymers of I with MCA gave low molecular weight polymers, but copolymers obtained with I and AN were high molecular weight polymers. In the reaction of I and MMA, high molecular weight copolymer was obtained only at temperatures above 80°C. Thus, obtained polymers were not the alternating copolymers and possessed high I content in all the cases. From the above results, macrozwitterionic mechanism was suggested as discussed.

Vinyl Sulfonate/Vinyl Amide Copolymers and Different Surfactants As Suitable Systems in Eorat Higher Temperatures and Salinities

For enhanced oil recovery flooding processes there will be an increasing demand for polymers having high temperature and electrolyte stability. High molecular weight copolymers based on vinyl sulfonate, vinyl amide, and acryl amide show high performances in matching these demanding requirements. Surfactants are also known that are stable under these conditions, resulting in high deoiling rates. The aim of the present article is to demonstrate the influence of alkylphenol ethoxylates and their corresponding ether sulfonates on VS/VA/AM copolymer solutions. Aqueous solutions of such copolymers were added to varying quantities of nonionic and anionic surfactants at different temperatures using salinity scans. This article discusses the results of experiments with solutions of copolymers and surfactants in terms of compatibility, viscosity yield, flow properties, shear stability, injectability, thermostability, and oil recovery. Solutions of alkylphenol ethoxylates and/or ether sulfonates show nearly the same compatibility within a broad range of temperature and salinity, both with and without polymers. Relatively small amounts of surfactants are able to influence the EOR (Enhanced Oil Recovery) properties of the polymer solutions, giving several interesting aspects for improved oil recovery.

Absence of the nitrogen reserve polymer cyanophycin from marineSynechococcusspecies

Cyanophycin is a high molecular weight co-polymer of aspartate and arginine, hitherto considered characteristic of all cyanobacteria. Chemical analysis and radioisotopic incorporation procedures have shown that precipitable cyanophycin is absent from the five species of Synechococcus tested, including the marine Synechococcus WH7803 (type DC2). The implications with respect to the role of cyanobacterial nitrogen reserves are discussed.

Absence of the nitrogen reserve polymer cyanophycin from marine Synechococcus species

Cyanophycin is a high molecular weight co-polymer of aspartate and arginine, hitherto considered characteristic of all cyanobacteria. Chemical analysis and radioisotopic incorporation procedures have shown that precipitable cyanophycin is absent from the five species of Synechococcus tested, including the marine Synechococcus WH7803 (type DC2). The implications with respect to the role of cyanobacterial nitrogen reserves are discussed.

Application of ductile polymeric coatings onto graphite fibers

AbstractThin, high molecular weight copolymers have been applied to the surfaces of commercial, 8 micron diameter, graphite fibers by electropolymerization. Random copolymers were obtained, and the process appears to be consistent with the rules of standard free radical copolymerization. Coating thickness, Tg, and modulus can be systematically controlled. Very preliminary mechanical property measurements indicate a substantially improved impact strength and reduction in the interlaminar shear strength. These effects may be related to poor adhesion between the interlayer and the epoxy resin, however, which may be corrected by use of a “top layer” of appropriate composition.

Coordination polymerization of ω‐alkenoates and ω‐epoxyalkanoates

AbstractAs functional polymers have become more and more used, the need for a general synthesis of addition polymers with functional groups became greatly important. We have achieved the polymerization of ω‐alkenoates with coordination initiators of the Ziegler‐Natta initiation type using titanium trichloride‐based transition metal initiators modified with dialkylaluminum chloride. To accomplish this polymerization required that the ω‐alkenoates be precomplexed with dialkylaluminum chloride. High molecular weight homopolymers and copolymers with olefins have been obtained. The polymerization of ω‐epoxyalkanoates with coordinative anionic polymerization systems based on triethylaluminum/water/acetylacetone (1.0/0.5/1.0) has also been accomplished. Homo‐ and copolymers of high molecular weight and of relatively narrow molecular weight distribution have been prepared. All polymers and copolymers of functional olefins and epoxides have been characterized and the study of the reactivity of the functional groups attached via a flexible spacer to the polymer main chain has been started. Special attention was given to the classical cationic copolymerization of trioxane with derivatives of ω‐epoxyundecanoate to prepare novel functional polyoxymethylenes of potential commercial interest.