Alkylene Phosphate Research Articles

Synthesis and Topological Trapping of Cyclic Poly(alkylene phosphates)

The zwitterionic ring-opening polymerization of 2-isopropoxy-2-oxo-1,3,2-dioxaphospholane (iPP) with N-heterocyclic carbenes (NHC) generates poly(alkylene phosphate)s with molecular weights of Mn = 55000–202000 Da. MALDI-TOF mass spectrometry provided clear evidence for cyclic poly(alkylene phosphate)s (poly(iPP)) for lower molecular weight fractions (m/z ≤ 3000). The cyclic topology of the higher molecular weight fractions was inferred by trapping of poly(iPP) in cross-linked 2-hydroxyethyl methacrylate (HEMA) hydrogels. Cross-linked HEMA hydrogels were generated in the presence of a high molecular weight (Mn = 202000 Da) poly(iPP) generated from the zwitterionic ring-opening polymerization of iPP with the NHC 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene 2. Extraction of the resulting gel with methanol for 11 days revealed that 36% of the poly(iPP) was retained in the gel, whereas a linear poly(iPP) was completely extracted under similar conditions. The retention of the poly(iPP)s in the gels is attrib...

Polymers with Esters of Phosphoric Acid Units: From Synthesis, Models of Biopolymers to PolymerInorganic Hybrids

AbstractSyntheses, some properties, and applications of the poly(alkylene phosphate)s prepared either by ring‐opening polymerization (ROP) or by polycondensation are described mostly on the basis of the data from our laboratories. The ROP of some cyclic phosphates and H‐phosphonates are living and/or controlled process. Transesterification of the products of the reaction of an excess of dimethylphosphonate with glycols leads to polymers with Mn close to 5×104. Poly(alkylene phosphate)s with five or six atoms in repeating units bear resemblance to the main chains of nucleic and teichoic acids. These and similar poly(alkylene phosphate)s with different repeating units were used as liquid membranes for the efficient separation of cations as well as to modify the medium for CaCO3 crystallization. In this latter process, a diblock copolymer with ionic and nonionic block was used. Poly(alkylene phosphate)s constituted the ionic block and the nonionic block was formed from poly(ethylene glycol); together with CaCO3 polymerinorganic hybrids were formed.

Synthesis of poly(oxyethylene phosphate)-g-poly(ethylene oxide) via the “grafting onto” approach by “click” chemistry

INTRODUCTION Brush copolymers, composed of polymeric arms regularly and densely spaced along a polymeric backbone, have been actively investigated for pharmaceutical applications like polymer carriers of drugs, because of their ability to self-assemble into well-defined nano-objects. Among the numerous macromolecular systems potentially available as drug delivery, polymers with alkylene H-phosphonate repeating units in the backbone are of particular interest due to their biodegradability and biocompatibility. Moreover, the pendant functional ability enables modification of the polymer backbone, which alters physical and chemical properties. Previous works describe successful strategies for appending functionalities onto polyphosphoester backbone by postpolymerization modification, via oxidation or addition reactions. In particular, Atherton–Todd reaction has been widely used to immobilize bioactive substances onto poly(alkylene H-phosphonate)s as this reaction proceeds in mild conditions with practically a quantitative yield. Introduction of biocompatible polymeric poly(ethylene oxide) (PEO) pendant groups has also been reported. Penczek and Pretula have first functionalized poly(alkylene H-phosphonate)s into the corresponding poly(alkylene phosphate)s. The hydroxyl functionality has then been used to initiate the polymerization of ethylene oxide according to a ‘‘grafting from’’ strategy, leading to poly(alkylene phosphate)-g-poly(ethylene oxide)s with a calculated graft length higher than two. They have also used the grafting onto strategy to anchorage PEO 200 onto poly(alkylene H-phosphonate)s beforehand oxidized. Recently, Wang et al. have reported the grafting of azide-functionalized PEO 2,000 onto ‘‘clickable’’ poly(alkylene phosphate) copolymer by Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition, obtained by ring-opening polymerization of an alkyne-functionalized five-membered cyclic phosphoester monomer, with a grafting efficiency of 42%. The Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition is so far the most studied and reliable example of ‘‘click’’ chemistry philosophy initially introduced by Sharpless and coworkers. ‘‘Click’’ chemistry benefits from the facile introduction of azide and alkyne groups into organic and polymer molecules, the stability of these groups to many reaction conditions, and the tolerance of the reaction to the presence of other functional groups. Thus, the application of ‘‘click’’ chemistry to aliphatic polyesters appeared promising and particularly valuable, given the sensitivity of the polyester backbone to the conditions required for many conventional organic transformations and couplings.

Phosphorylation of Polyols with H3PO4: Towards Simple Synthesis of Poly(alkylene phosphate)s

Polycondensation of ethylene glycol and of glycerol with H 3 PO 4 elaborated recently is summarized. Surprisingly, this apparently simple reaction, leading to a new class of synthetic polymers, has not previously been studied. In both reactions, soluble oligomers are formed, in spite of H 3 PO 4 , the class A3 component, being used. Dealkylation prevents the formation of high molar mass products, while also influencing the stability of the triesters in the case of ethylene glycol condensation. Polycondensation does not proceed directly with H 3 PO 4 . Independent kinetic experiments reveal that in the rate-controlling step, pyrophosphoric acid is formed. In polycondensation of glycerol, five- and six-membered rings are present in the main chain, indicating that the A3/B3 system has been converted into the A2/B2 system (at least partially). Both polymers have been shown to be efficient modulators of the CaCO 3 crystallization.

Poly(alkylene phosphates): From Synthetic Models of Biomacromolecules and Biomembranes toward Polymer−Inorganic Hybrids (Mimicking Biomineralization)

Syntheses of poly(alkylene phosphates), with repeating units having two or three methylene groups and phosphoryl groups and mimicking backbones of biomacromolecules, are reviewed. Two major methods elaborated in this laboratory, namely, ring-opening polymerization and transesterification, are described. The resulting polymers were used as carriers of cations (Ca2+ and Mg2+) in membrane processes and in controlling the crystallization of CaCO3, in a process related to biomineralization.

Synthesis of a triblock copolymer: Poly(ethylene glycol)‐poly(alkylene phosphate)‐poly(ethylene glycol) as a modifier of CaCO3 crystallization

AbstractTriblock copolymer poly(ethylene glycol)‐poly(alkylene phosphate)‐poly(ethylene glycol) was prepared by first reacting hexamethylene glycol with dimethyl‐H‐phosphonate at conditions of transesterification and then replacing the CH3OP(O)(H)O‐… end‐groups by monomethyl ether of poly(ethylene glycol). The course of reaction was studied by 31P NMR indicating complete conversion. After oxidation the poly(alkylene H‐phosphonate was converted into the final triblock polyphosphate. This triblock copolymer was used as a modifier of CaCO3 crystallization. Unusual semi open empty spheres resulted, composed of small crystallites of the size (diameter) equal to 40–90 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 650–657, 2005

Competitive binding of Na + and Ca 2+ ions to teichoic acid analogues

The competitive binding of monovalent and divalent counterions to poly(alkylene phosphate) related to bacterial teichoic acids and poly(styrenesulfonate) was studied experimentally by potentiometry with ion-selective electrodes. The binding of calcium ions and the release of sodium ions accompanying calcium ions binding in aqueous solutions of the polyelectrolytes was analysed and the mean exchange ratio Na+/Ca2+ was estimated. It was found that in the process of addition of calcium ions to sodium poly(alkylene phosphate) and sodium poly(styrenesulfonate) solutions all the Ca2+ ions added are bound to polyions and the initially condensed Na+ ions are released proportionally to the concentration of the added Ca2+ ions up to the critical concentration of the Ca2+ ions added. For a molar concentration ratio of calcium counterions to charged groups on the polyion up to 0.20 the exchange ratio was approximately equal to 1 or 2 for the sodium poly(alkylene phosphate)/CaCl2 and sodium poly(styrenesulfonate)/CaCl2 systems, respectively.

Synthesis of high molar mass poly(alkylene phosphate)s by polyaddition of diepoxides to difunctional phosphoric acids: Unusual elimination of the side reactions

AbstractThe reaction between diepoxides and difunctional acids of phosphorus was studied as a potential route to linear polyesters of phosphoric acid. The reaction between diepoxide and POH groups in H3PO4 and related acids leads to linear phosphates, but cyclic phosphates are also formed as side products. The formation of such unreactive groups terminates polyaddition. However, cyclization is practically eliminated when the epoxide ring is fused to another ring, such as in cyclohexene oxide. A commercially available diepoxide containing two cyclohexene oxide moieties, 3,4‐epoxycyclohexylmethyl‐3,4‐epoxycyclohexanecarboxylate (ERL), was, therefore, used for polyaddition studies. Indeed, in the polyaddition of ERL with ethylphosphoric acid, high molecular weight (number‐average molecular weight up to 104) linear polyphosphates were obtained. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3024–3033, 2001

Conformation and packing of poly(alkylene phosphate) chains in the crystal lattice. Part II: Temperature FTIR studies

The infra-red absorption of recrystallized samples of the polyhexa-, polyhepta-, polyocta-, polynona-, polydeca- and polydodecamethylenephosphate was measured during the heating, from the room temperature to the temperature higher than the melting temperature of the polymer examined. The heating induced changes of FTIR spectra proved, that the spatially arranged polyphosphate chains are cross-linked by the PO⋯H–O hydrogen bonds, whose properties consist with the properties of the theoretically predicted hydrogen bonds. Moreover, the strong crystal field splitting of the rocking vibrations of the polyphosphate monomer unit methylene chain and of the (P)– O–C stretching vibrations has been observed. As was founded, the dispersion curves of rocking vibrations of the polyphosphate chain (CH2)ntrans sequences may be approximated by the exponential function: ν=ν∞ exp (C/n). The crystal field splitting effects proved, that the unit cell of polyphosphate crystals contain two polyphosphate monomer unit, and that the conformation of the polyphosphate extended chains is close to the conformation of the modeled polyphosphate extended chains.

Conductive blends of polyaniline with plasticized poly(methyl methacrylate)

Polyaniline (PANI) protonated with camphorsulfonic acid (CSA) and three different poly(alkylene phosphates) (PAPs) (where alkylene = pentylene, hexylene, or nonylene) was used in the fabrication of conductive polyaniline–poly(methyl methacrylate) (PMMA) blends. The lowest percolation threshold (fp = 0.041 wt %) was obtained for the PANI(CSA)0.5–PMMA blend plasticized with 35 wt % of dibutyl phtalate (DBPh). This blend is also very resistant against the deprotonation of its conductive phase in basic solutions of pH = 9. In the case of blends prepared with the use of PAPs as PANI dopants, the percolation threshold strongly depends on the length of the hydrophobic spacer (alkylene group) in the dopant. The percolation threshold decreases in the order PPP > PHP > PNP, whereas the resistance against deprotonation in basic solutions decreases in the following inverse order: PNP > PHP > PPP. This last observation can be rationalized by increasing contribution of hydrophobic segments in the polymeric dopant, when going from PPP to PNP, which renders polyaniline more resistance toward the penetration by aqueous basic solutions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 471–479, 1999

Interaction of sodium and calcium ions with poly(alkylene phosphate)—a synthetic analogue of natural teichoic acids

The competitive binding of sodium and calcium ions to poly(alkylene phosphate)s, which can be considered as synthetic models of bacterial teichoic acids, and to poly(styrenesulfonate)s was studied experimentally by potentiometry with ion-selective electrodes. The fractions of apparently free counterions, ffi, were determined and compared with theoretical predictions obtained from the Poisson–Boltzmann theory applied to the cylindrical cell model of polyelectrolyte solutions containing a mixture of counterions differing in charge. For the studied systems, the dependence of ffNa and ffCa on the composition of the counterion mixture and on a charge density parameter of the polyion was found to be fairly well described by theory. For poly(alkylene phosphate)s the calculated values of ffi noticeably exceeded the measured fractions of apparently free ions. Much better agreement between theory and experiment was obtained if the effective value of the charge density parameter was used.

Conformation and packing of poly(alkylene phosphate) chains in the crystal lattice. Part I: molecular modelling and wide-angle X-ray scattering

Molecular modelling of the poly(alkylene phosphates) suggests a structure in which the repeat distances appear to be in agreement with those indicated by wide angle X-ray diffraction studies of the semi-crystalline polymer. The extended zig-zag chains lie in a parallel array in stacks of pleated sheets. There are lines of phosphoryl groups, linked by hydrogen bonding, running in one direction through the structure which appear to be suitable for the selective transport of ions.

Polyesters of phosphoric acid: Synthesis and kinetics of hydrolysis

AbstractThree major methods have been elaborated in our laboratory for preparation of polymers with poly(alkylene phosphates) backbones: ring‐opening polymerization, poly‐condensation and transesterification, and polyaddition. The second method is based on the reaction of the commercially available compounds, namely dialkyl (or diaryl)‐H‐phosphonates and glycols. Reaction of the aliphatic H‐phosphonates with aliphatic glycols is a reversible process, whereas polycondensation of diphenyl H‐phosphonates with aliphatic and cycloaliphatic diols is practically irreversible. This latter method has recently been developed and is described in this paper.Poly H‐phosphonates with M̄n up to 40–103 were prepared. Polymers are easily oxidized and quantitatively converted into the relatively stable poly(alkylene phosphates). Some physical properties of these polymers and kinetics of their hydrolysis is discussed.

Preparation of Poly(alkylene H-phosphonate)s and Their Derivatives by Polycondensation of Diphenyl H-Phosphonate with Diols and Subsequent Transformations

A new method of preparation of poly(alkylene H-phosphonate)s (1) by polycondensation of diphenyl H-phosphonate with diols such as 1,10-decanediol or tetra(oxyethylene) glycol is described. These polymers can be converted into poly(alkylene phosphate)smimicking backbones of nucleic acids and other biomacromolecules. The described method is the only one allowing simple preparation of this important class of polymers. This method eliminates the major side reaction taking place when dialkyl H-phosphonates are used and is related to the C-alkylation and formation of the unreactive ether end groups. Reaction of diphenyl H-phosphonate with alcohols is practically irreversible and can be performed without removing phenol, formed as a byproduct of condensation. It can be carried out in solvent or in bulk at temperature 80−200 °C. Removing phenol enhances, however, formation of polymers with higher Mn. Polymers with Mn ∼ 30 × 103 were obtained and characterized as such or in the form of their derivatives. Chlorin...

Polycondensation route leading to poly(alkylene phosphate)s

AbstractA polytransesterification method of preparation of the high‐molecular‐weight poly(alkylene H‐phosphonates) ‐ polymers bearing a reactive ‐OP(O)(H)O‐units, is described:magnified imageMechanism of transesterification involves mostly ‐OP(O)(H)O⊖, Mt⊕ “growing species”. The polyphosphonates were converted into a number of derivative polymers, like poly(alkylene phosphates), prepared by a direct oxidation, without decreasing of the DPn of the parent polymers.

Competitive counterion binding to poly(alkylene phosphate)s related to natural teichoic acids. The Poisson‐Boltzmann approach

AbstractThe problem of competitive metal ion binding to poly(alkylene phosphate)s, considered as synthetic models of natural teichoic acids, was analysed theoretically applying the Poisson‐Boltzmann (PB) equation to a cylindrical cell model. There were calculated the radial distribution functions as well as the degree of ion binding of mono‐and divalent metal ions to polyphosphate ions in solutions of different concentrations ranging from 10−5 M to 10−2 M and containing different amounts of M⊕ and M2+ counterions. For comparison, analogous calculations were performed also for poly(styrenesulfonate)s. The results indicate the preferential binding of divalent metal ions to polyphosphate ions over monovalent ones. The selectivity for M2+ ions is concentration dependent and increases with decreasing the polymer solution concentration. It results from PB calculations, that condensation of divalent metal ions at the surface of polyion chains seems to be responsible for preferential binding of biologically important metal ions, for example magnesium, to natural teichoic acids and their synthetic analogues.

Spectroscopic studies of polyaniline protonation with poly(alkylene phosphates)

Polyaniline doped with poly(alkylene phosphates) has been studied by Fourier transform infra-red, X-ray photoelectron and ultraviolet/visible spectroscopies. The protonation of the polymer was indicated by the appearance of infra-red modes characteristic of polyaniline salts and by the bands typical of polyphosphates at ca. 1000 cm −1. X-ray photoelectron spectra showed a decrease in the concentration of imine groups as well as the co-existence of ionized and unionized phosphates independent of the doping level. The influence of the protonation method on the obtained product was observed.

ChemInform Abstract: Models of Biopolymers and Bioanalogous Polymers with Backbones of Poly( alkylene phosphate)s

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Spectroscopic Properties of Polyaniline Protonated with Poly(alkylene phosphates)

The reaction of polyaniline with new high-molecular-weight protonating agents, namely poly(alkylene phosphates), has been studied by UV/vis spectroscopy. The spectra were recorded both in the solid state and in organic solvents since polyemeraldine protonated with poly(alkylene phosphates) can be stabilized in the solution without precipitation. The influence of the molar ratio of both polymers and of the length of alkylene chain on the protonation level was observed. The protonation was evidenced by the appearance of polaron bands at 420 and ca. 900 nm. The addition of polar solvent increased the degree of protonation. The best protonation was achieved in m-cresol solution, whose principal features were the appearance of intrachain (free carrier) excitation at 430 nm, the decrease of the ca. 800 nm band intensity, and the increase of a long absorption tail into the near-infrared.

Amino acids attached to poly(alkylene phosphate)s, 1. Synthesis

AbstractThe synthesis of poly(alkylene phosphate)s with attached amino acids was elaborated. Two methods of coupling through P—NH bond were used. They were based on the direct reaction of amino acid esters or N,O‐bis(trimethylsilyl) substituted amino acids with poly(alkylene chlorophosphate)s. The assumed microstructure of the resulting polymers was confirmed by analysis of the 1H, 13C and 31P NMR spectra. Preliminary data on the hydrolytic stability of amino acids modified poly(alkylene phosphate)s are also given.