Homologous Series Of Polymers Research Articles

Homologue series detection and management in LC-MS data with homologueDiscoverer.

Untargeted metabolomics data analysis is highly labour intensive and can be severely frustrated by both experimental noise and redundant features. Homologous polymer series is a particular case of features that can either represent large numbers of noise features or alternatively represent features of interest with large peak redundancy. Here, we present homologueDiscoverer, an R package that allows for the targeted and untargeted detection of homologue series as well as their evaluation and management using interactive plots and simple local database functionalities. homologueDiscoverer is freely available at GitHub https://github.com/kevinmildau/homologueDiscoverer. Supplementary data are available at Bioinformatics online.

The effect of polymer backbone chemistry on the induction of the accelerated blood clearance in polymer modified liposomes

A variety of water-soluble polymers, when attached to a liposome, substantially increase liposome circulation half-life in animals. However, in certain conditions, liposomes modified with the most widely used polymer, polyethylene glycol (PEG), induce an IgM response resulting in an accelerated blood clearance (ABC) of the liposome upon the second injection. Modification of liposomes with other water-soluble polymers: HPMA (poly[N-(2-hydroxypropyl) methacrylamide]), PVP (poly(vinylpyrrolidone)), PMOX (poly(2-methyl-2-oxazoline)), PDMA (poly(N,N-dimethyl acrylamide)), and PAcM (poly(N-acryloyl morpholine)), increases circulation times of liposomes; but a precise comparison of their ability to promote long circulation or induce the ABC effect has not been reported. To obtain a more nuanced understanding of the role of polymer structure/MW to promote long circulation, we synthesized a library of polymer diacyl chain lipids with low polydispersity (1.04–1.09), similar polymer molecular weights (2.1–2.5kDa) and incorporated them into 100nm liposomes of a narrow polydispersity (0.25–1.3) composed of polymer–lipid/hydrogenated soy phosphatidylcholine/cholesterol/diD: 5.0/54.5/40/0.5. We confirm that HPMA, PVP, PMOX, PDMA and PAcM modified liposome have increased circulation times in rodents and that PVP, PDMA, and PAcM do not induce the ABC effect. We demonstrate for the first time, that HPMA does not cause an ABC effect whereas PMOX induces a pronounced ABC effect in rats. We find that a single dose of liposomes coated with PEG and PMOX generates an IgM response in rats towards the respective polymer. Finally, in this homologous polymer series, we observe a positive correlation (R=0.84 in rats, R=0.92 in mice) between the circulation time of polymer-modified liposomes and polymer viscosity; PEG and PMOX, the polymers that can initiate an ABC response were the two most viscous polymers. Our findings suggest that polymers that do not cause an ABC effect such as, HPMA or PVP, deserve further consideration as polymer coatings to improve the circulation of liposomes and other nanoparticles.

Separation of polysorbates by liquid chromatography on a HILIC column and identification of peaks by MALDI-TOF MS

Polysorbates can be separated according to their functionality and architecture by liquid chromatography on a hydrophilic interaction chromatography (HILIC) column in acetone-water mobile phases containing 90-97% acetone. The different polymer homologous series are separated according to the number of terminal hydroxy groups and elute as narrow peaks. The hydrophilic part (ethoxylates of sorbitan, isosorbide, and poly(ethyleneglycol)) and amphiphilic funtionalites (ethoxylated mono-, di-, tri-, and tetraesters) were separated by HILIC mode of high-performance liquid chromatography (HPLC). All these separated functionaities are identified and confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS). This combination of HPLC and MALDI-TOF MS has been proven to be an excellent tool for the characterization of heterogenous complex samples.

Characterization of synthetic copolymers by interaction polymer chromatography: Separation by microstructure

Gradient elution of synthetic polymers has been studied both theoretically and experimentally using normal and reversed-phase HPLC systems. An accurate equation describing the gradient elution of polymer-homologous series in the context of continuous random-flight model of a flexible polymer chain interacting with attractive surface of the porous material has been derived and experimentally verified against a series of narrow polystyrene standards. Both the theory and the experiment predict the existence of molar mass-independent gradient elution at critical point of adsorption (CPA). The extension of the theory to synthetic copolymers predicts the existence of the CPA for statistical copolymers and describes its dependence on chemical composition and microstructure (blockiness) of the polymer chains. One of the important theoretical conclusions is that blockiness always increases the retention, so that blockier polymer chains elute later than their more random counterparts with the same chemical composition. This prediction has been confirmed experimentally using block and statistical styrene-methylmethacrylate copolymers. Block copolymers do not have CPA and always elute between critical points of the corresponding homopolymers. The retention depends on the polymer molar mass and increases with the length of the blocks from a stronger absorbing monomer. These findings provide theoretical and experimental bases for separation of statistical and block copolymers by chemical composition and microstructure of polymer chains.

Separation of all oligomers in polyethylene glycols and their monomethyl ethers by one-dimensional liquid chromatography

Different polymer homologous series having the same repeat unit, but different end groups, can be separated by one-dimensional LAC according to the number of repeat units and functionality, if a favorable combination of the interaction parameters of the repeat unit and the end groups can be found. As an example, polyethylene glycol (PEG) can be determined in PEG monomethyl ethers. The molar mass distribution of the minor component in such samples can be determined even at concentrations of a few percent.

A data base for polymer chromatography: Temperature dependence of interaction parameters in liquid adsorption chromatography

The temperature dependence of retention behaviour of polyethylene glycol (PEG) and its mono- and dimethyl ethers was studied on various RP columns in different mobile phases. The accessible volumes and the interaction parameters were determined from slope and intercept in a plot of the elution volumes of the oligomers of a polymer homologous series as a function of the difference of the elution volumes of consecutive oligomers. A quite different dependence of the interaction parameters was observed in the different mobile phases. While in methanol-water the interaction parameter decreases with increasing temperature, the opposite effect is observed in acetonitrile (ACN)-water. In acetone-water, the temperature dependence is almost negligible.

Property Modification via Crosslinking in CBDO-Based Copolyterephthalates

The work discussed herein focuses on the examination of the effects of crosslinking CBDO containing copolyterephthalates. A series of copolyterephthalates containing the aliphatic CBDO monomer along with aromatic diols was examined. These materials incorporate CBDO, bisphenol A, phloroglucinol, and terephthaloyl chloride and were made using standard solution polymerization techniques. The phloroglucinol, a trifunctional aromatic alcohol, was used as the crosslinking agent. The series of materials examined included both linear and crosslinked systems. The percent incorporations of the selected monomers, CBDO, bisphenol A, phloroglucinol, and terephthaloyl chloride, was varied to create a homologous series of polymers. Each polymer material was characterized for both thermal and mechanical performance.

Microwave assisted synthesis and characterization of end functionalized poly(propylene oxide) as model compounds

End functionalized poly(propylene oxide)s with n-alkyl endgroups are synthesized by anionic ring opening polymerization of propylene oxide (PO) in bulk employing controlled microwave heating in sealed vessels. Different alcohols ranging from n-butanol to n-octadecanol are used as initiator and 2–10 propylene oxide units are added on average. A continuous decrease of internal pressure during the sealed vessel experiment reflects the consumption of PO monomer and the completion of the reaction is confirmed by a drop of the internal pressure to zero. The products are characterized by size exclusion chromatography (SEC), liquid chromatography at critical conditions (LCCC) and liquid adsorption chromatography (LAC). SEC with coupled density and refractive index (RI) detection provides information on the chemical composition along the molar mass distribution. LCCC allows a separation of the individual polymer homologous series according to their end groups. In LAC, the alkyl terminated chains elute later than the non-functional chains and can be separated to the baseline according to the number of repeat units.

Characterization of different reversed phase systems in liquid adsorption chromatography of polymer homologous series

The interaction parameter of a given repeat unit in liquid adsorption chromatography (LAC) can be determined from the slope in a plot of the elution volumes versus the difference in elution volumes of subsequent monomers. In such a plot, the intercept represents the void volume, and from the slope the adsorption interaction parameter can be calculated. This parameter is independent of column dimensions and pore diameter and can thus be used as a measure of the interaction of a given repeat unit with the surface of a stationary phase in a given mobile phase composition. The interaction parameter can also be obtained from the slope in a plot of the logarithmic retention factors k versus the number of repeat units n or from the slope in a plot of the logarithmic difference in elution volumes of subsequent monomers versus n. The values obtained by the three different approaches are in good agreement. In a given mobile phase, the interaction parameter of a given repeat unit was found to be almost the same for various alkyl bonded columns from different producers. The retention of a given oligomer depends as well on the interaction parameter as on the pore dimensions (and thus the internal pore surface) of the stationary phase. The pore surface can be determined from the intercept in a plot of the logarithmic difference in elution volumes of (subsequent) nonfunctional monomers as a function of n. As the interaction parameter of a given repeat unit in a given mobile phase is the same for stationary phases with the same chemical nature, retention can be adjusted by selection of the pore surface. On a given stationary phase, there is a linear dependence between interaction parameter and mobile phase composition.

The rule parameters in liquid adsorption chromatography of polymer homologous series and their determination

The separation of polymer homologous series is governed by two rule parameters: the interaction parameter c of the repeat unit and the sorbent surface S (relation of pore volume to pore diameter). The interaction parameter is independent on column dimensions and pore diameter. In a plot of elution volumes V n versus the difference Δ V = V n − V n−1 in elution volumes of consecutive oligomers, straight lines are obtained, the intercept of which yields the accessible volume. Using the accessible volume as the hold-up volume in the calculation of the retention factor k, a strictly linear dependence of ln k versus the number of the repeat units n is observed (Martin's plot). The interaction parameter c can be determined experimentally by three different approaches: from the slope in a plot of V versus Δ V, from the slope in Martin's plot (ln k versus n), and from the intercept in a plot of ln(Δ V) versus n. The pore surface is obtained from the intercept in Martin's plot (ln k versus n) or the intercept in a plot of ln( ΔV) versus n. The results obtained by the different approaches agree very well. The theoretical predictions are verified by comparison with the experimental data obtained on columns with different pore diameter and pore volume and thus, different pore surface at conditions corresponding to the same interaction parameter.

Liquid Crystal Polymers Containing Ni(II), Pd(II), or VO(II) in the Main Chain

The synthesis and the phase behavior of a homologous series of polymers of 4,4'-[1,12-dodecanediylbis(oxy)]bis(benzoic acid) with bis[N-[[2,4-dihydroxyphenyl]methylene]alkylamino]nickel(II), -palladium(II) and -oxovanadium(II) are reported. Calorimetric and X-ray diffraction data and dynamic viscosity measurements are consistent with the occurrence of nematic mesomorphism for all polymers. The nematic phase, which is monotropic for some of the nickel-containing polymers, is comparatively more stable for those containing palladium. Polymers containing the oxovanadium group show also enantiotropic smectic mesomorphism. The mesophase properties of ligand systems are also discussed.

Smectic A structure in main-chain liquid crystalline polymers with two different spacers

We have prepared a homologous series of polymers, BP-CO4-On (n= 3-15). [ILLEGIBLE] The BP-CO4-On polymers are classified as a new type of main-chain liquid crystalline polymer, characterized by having the mesogenic biphenyl moieties and the two different aliphatic spacers incorporated in a regularly alternate fashion. All the polymers form a smectic A phase. The smectic behaviour and structure have been examined by differential scanning, optical microscopic and x-ray methods, concentrating on how the two spacers, which are different in length and of odd-even nature, are accommodated into a smectic layer structure.

A new type of main-chain liquid-crystal polymer derived from 4′-hydroxybiphenyl-4-carboxylic acid and its smectic mesophase behaviour

A homologous series of polymers (PHBC-n) has been prepared from 4′-hydroxybiphenyl-4-carboxylic acid and ω-bromoalkan-1-ols containing five to nine methylene units which can serve as mesogen and flexible spacer groups, respectively. The PHBC-n polymers are characterized by having two different linkage groups, ether and ester groups, to connect the biphenyl mesogen to the methylene spacer, and are classified on a new type of main-chain liquid-crystal polymer. All polymers exhibit the enantiotropic smectic phase. The smectic behaviour and structure were examined by differential scanning calorimetry, optical microscopic and X-ray diffraction methods, and are discussed in comparison with the corresponding date of the BB-n polyesters, which include only the ester linkage group.

A topological approach to the modelling of polymer properties (The tempo method)

The topological extrapolation method for the modelling of polymer properties (TEMPO) is outlined. It is based on the topological description of the polymer elementary units by means of the normalised Wiener number represented as a polynomial in degree 3 with respect to the number of atoms. The properties of the infinite polymers are evaluated by making use of a specific extrapolating technique applied to regression models derived for the respective polymerhomologous series. The inherent topological background of the TEMPO approach makes its predictions more reliable than the known Pade approximation. The method is extensively applied to the calculation of π-electron energies and energy gaps of various conjugated polymers, as well as to the assessment of the melting point, density, refractive index, and specific rotation of some industrially produced polymers.

Correlation of glass transition temperature and molecular weight: A model based on the principle of corresponding states

AbstractThe molecular weight dependence of the glass transition temperatures of polystyrene, polyα‐methyl styrene, polyisopropylα‐methyl styrene, polymethylmethacrylate, polyvinylchloride, poly‐isobutylene, polyisoprene, and poly‐N‐octadecylmaleimide is described by an equation developed from the Principle of Corresponding States. A statistical analysis is used to test the adequacy of the equation, and it is shown that from a statistical point of view the three molecular parameters, Se/Sm, ε/ε, and Ce/Cm, characterizing, respectively, the ratios of contact area, lattice energy, and segmental mobility of end groups relative to repeating segments along the chain, will adequately describe the data. It is also shown that in one limit the equation reduces to the well‐known Ueberreiter‐Kanig result, which for most cases is a good first approximation to the data. The molecular weight‐TG data were used to estimate the depression of the glass transition temperature of polystyrene and polymethylmethacrylate by a series of plasticizers. It was concluded that in the absence of important changes in the molecular structure within a homologous series of polymers, the Principle of Corresponding States can be employed to describe the molecular weight dependence of glass transition temperature over the entire range of available data.

Inherently Flexible Thermotropic Main Chain Polymeric Liquid Crystals

Abstract Phase behavior (isotropic—nematic transition, disorder in the crystal) and order of chains in the mesophase (orientational and conformational) are investigated in the homologous series of polymers and corresponding Siamese twin models. Results from the following experiments are presented: DSC (normal and high pressure), polarizing microscopy, broad line NMR (PMR and DMR), small angle X-ray and neutron scattering, induced magnetic birefringence and melt rheology. Influence of chain length, spacer length and parity, temperature and concentration in nematic solutions on nature and level of order is discussed. Molecular segregation by chain length in the nematic—isotropic biphase is considered in relation to its impact on morphology of the isotropic, nematic and solid phases. This series provides a model system for characterization of inherently flexible main chain PLCs formed by alternating mesogens and spacers. Such PLCs are easily processable materials with potentially high levels of micro and macroorder.

Cationic surfactants in marine fish

A polymer-homologous series of nitrogen-containing compounds, tentatively identified as N-pentyl alkyl amines or N-butyl alkyl amides, with the alkyls ranging from dodecyl to octadecyl, was detected in fish off Nova Scotia, Canada. The origin of these compounds is not known.

Biosynthesis of enterobacterial common antigen.

Cultures of Salmonella typhimurium pulse-labeled with N-acetyl-D-[3H]glucosamine ([3H]GlcNAc) incorporated isotope into a GlcNAc-linked lipid that was tentatively identified as GlcNAc-pyrophosphorylundecaprenol. The incorporation of [3H]GlcNAc into this compound was abolished when cells were pulse-labeled in the presence of the antibiotic tunicamycin. Tunicamycin also abolished the in vivo synthesis of the haptenic form of enterobacterial common antigen (ECA) in S. typhimurium as determined by the passive hemagglutination test. These data indicated that the synthesis of the GlcNAc-linked lipid is related to ECA synthesis. Support for this conclusion was provided by the following observations. Cultures of Escherichia coli and S. typhimurium incorporated [3H]GlcNAc into cell envelope components that migrated as a homologous series of polymers when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The [3H]GlcNAc-labeled polymers were not detected in mutants of E. coli and S. typhimurium defective in ECA synthesis due to lesions in either the rfe or rff gene clusters. These polymers were identified as ECA based on Western blot analyses employing anti-ECA monoclonal antibody. The incorporation of [3H]GlcNAc into ECA polymers was abolished by tunicamycin when the drug was added to cultures to give a minimum concentration of 3 micrograms/ml. In addition, pulse-chase experiments provided evidence for a precursor-product relationship between the GlcNAc-linked lipid and ECA. These results strongly suggest that the GlcNAc-linked lipid is involved in the biosynthesis of ECA in a manner analogous to the role of carrier lipid in the biosynthesis of O-antigen and peptidoglycan.

Analysis of the concept of polymer quasi-solution using data on the volume of mixing of polyethylene oligomers

Concentration dependences of the excess volume of mixing have been derived for mixtures of liquid homologues belonging to the same polymer-homologous series and also for homolog mixtures containing members of homomorphous series. The obtained functions have been analysed quantitatively using experimental data on the volume of mixing of higher linear alkanes, alkanols, and 1-chloroalkanes. The theory agrees with experiment for sufficiently long molecules. The lowest chain length limiting the range of applicability of the quasi-solution concept depends on the character of end groups.

Intrinsic viscosity versus molecular weight relationship of polystyrene in cis‐decahydronaphthalene

AbstractIntrinsic viscosities [η] and mean‐square radii of gyration 〈R〉 of a polymer homologous series of commercially available narrow‐molecular‐weight‐distribution polystyrene (PS) samples in a molecular‐weight range of 800 up to 24 · 106 were determined in cis‐decahydronaphthalene at 25°C by light‐scattering and viscosity measurements. These dilute solution properties were compared with those for PS in the good solvent toluene, in the constitutional isomer trans‐decahydronaphthalene both at 25°C and in cyclohexane at 34,5°C as a theta‐system.