A “chain fold band” in the infrared spectra of nylon 6

An absorption band found at 974 cm⁻¹ in the infrared spectra of “amorphous” nylon 6 films has been assigned to CH₂ wagging or twisting vibrations in molecular chain folds. Annealing amorphous films in air at increasing temperatures up to 150°C has been shown to induce a steady increase in the intensity of the absorption band at 974 cm⁻¹. Annealing at higher temperatures resulted in a sharp decrease in intensity up to an annealing temperature of 210°C. This sharp decrease coincided with a sharp increase in the long period determined by low-angle x-ray diffraction studies. Drawing amorphous films has been shown to induce a decrease in the intensity of the band at 974 cm⁻¹. Polarized infrared investigations of amorphous drawn films revealed that the band at 974 cm⁻¹ was strongly perpendicular in character. Treatment of amorphous films in water induced no frequency change in the band at 974 cm⁻¹.     

On the nature of “functional groups” in non-functionalized hypercrosslinked polystyrenes

The paper discusses the assignment of the absorbance band at 1700 cm⁻¹ in FTIR spectra of hypercrosslinked polystyrenes. This band is exceptionally intensive in the spectra of networks obtained by post-crosslinking styrene-0.5% DVB copolymer, swollen in ethylene dichloride, with monochlorodimethyl ether up to the maximum possible crosslinking degrees of 300%, 400% and 500% in the presence of non-oxidizing catalyst SnCl₄. Theoretically, in these networks each phenyl ring binds to neighboring phenyls through three, four or five methylene groups, respectively. Elemental analysis of the products seems to be deficient in C and H, thus allowing expectation of a surprisingly high percentage of oxygen. However, the traditional attribution of both the suspected high content of oxygen and the band at 1700 cm⁻¹ to aromatic carbonyl groups is incorrect. Treatment of hypercrosslinked polystyrenes with hydroxylamine, sodium bisulfite, ethyl orthoformiate or LiAlH₄ do not result in disappearance of the absorbance at 1700 cm⁻¹ in FTIR spectra and emergence of corresponding characteristic new bands. Solid state ¹³C NMR spectroscopy also confirms the absence of CO moieties in the above hypercrosslinked polystyrenes. The absorbance at 1700 cm⁻¹ disappears, while new bands in the range of 1670–1650 cm⁻¹ emerge, in the spectrum of the sample with 500% crosslinking degree after the reduction of its benzene rings via Birch reaction. This allows suggesting that the band at 1700 cm⁻¹ and its shoulders are caused by hindered vibrations of carbon–carbon bonds and valence angles in the aromatic fragments composing the rigid network with extremely high extent of mutual connectivity.     

Lattice dynamics of yttria: A combined investigation from spectrum measurements and first-principle calculations

C-type Y₂O₃ ceramics (relative density ~94%) were prepared at 1500 °C for 2 hours with 1% wt. ZnO as sintering aid. The cell parameters of Y₂O₃ from Rietveld refinements are a = 10.6113(1) Å, V = 1194.8(1) ų. The vibrational modes / lattice dynamics of Y₂O₃ were investigated using vibrational spectra (Raman and infrared reflection spectra) and first-principle (DFT) calculations. Eight of the 22 predicted first-order Raman modes and 12 of 16 predicted IR modes are observed and reliably assigned. For the observed vibrational modes, an excellent linearity (f_exp = 1.023f_theo, R² = 0.9999) between frequency from calculations (f_theo) and that from measurements (f_exp) is observed. Accordingly, the corrected frequency (f_cor) of vibrational modes, phonon band structure, and density of phonon states (DOPS) of Y₂O₃ are presented, in which, the frequency of phonons of Y₂O₃ is ≤625.2 cm⁻¹ (wavelength ≥16.0 μm) with a gap of 30.6 cm⁻¹ from 486.0 to 516.6 cm⁻¹ (wavelength 20.6 - 19.4 μm) at room temperature. The modes with f_theo ≥292.5 cm⁻¹ (f_cor ≥299.2 cm⁻¹) are dominated by the vibrations of O²⁻ (light atom vibrations) and the vibrational modes with f_theo ≤239.0 cm⁻¹ (f_cor ≤244.5 cm⁻¹) are dominated by the vibrations of both Y³⁺ and O²⁻ (co-vibrations). The three modes T_u⁽⁷⁾ at 301.6 cm⁻¹, T_u⁽¹⁰⁾ at 333.7 cm⁻¹, and T_u⁽¹²⁾ at 369.7 cm⁻¹ of Y-O stretch vibrations dominate the phonon dielectric constant and dielectric loss of Y₂O₃ with more than 85% contributions.     

Raman study of the microstructure changes of phenolic resin during pyrolysis

After curing, phenol‐formaldehyde resins were post‐cured at 160°C, and then carbonized and graphitized from 300°C to 2400°C. The structure of the resulting carbonized and graphitized resins were studied using X‐ray diffraction and Raman spectroscopy. Thermal fragmentation and condensation of the polymer structure occurred above 300°C. The crystal size of the cured phenolic resins increased with an increase in temperature. The crystal size increased from 0.997 nm to 1.085 nm when the heat‐treatment temperature rose from 160°C to 500°C. Above 600°C, the original resin structures disappeared completely. Below 1000°C, the stack size (L_c) increased very slowly. The values increased from 0.992 to 1.192 nm when the heattreatment temperature rose from 600°C to 1000°C. Above 1000°C, the stack size showed an increase with the increase in heat‐treatment temperature. The values increased from 1.192 to 2.366 nm when the temperature rose from 1000°C to 2400°C. The carbonized and graphitized resins were characterized using Raman spectroscopy. The Raman spectrra were recorded between 700 and 2000 cm⁻¹. Below 400°C, there were no carbon structures in the Raman spectra analysis. Above 500°C, G and D bands appeared. Raman spectra confirmed progressive structure ordering as heat‐treatment temperature increased. The frequency of the G band of all carbonized and graphitized samples shifted to 1600 cm⁻¹ from the 1582 cm⁻¹ of graphite. At the same temperature, the D band shifted to 1330 cm⁻¹ from the 1357 cm⁻¹ of the imperfect carbon. In the curve fitting analysis of the Raman spectra, a Gaussian shaped band centered at 1165 cm⁻¹ was included. This band has not been described before in the literature and is attributed to disordered structures, which are formed from the original polymeric structures. These polymeric structures formed unknown disordered structures and remained in the carbonized phenolic resins. Above 1800°C, this band disappeared completely. But, a weak peak is present near 1620 cm⁻¹. This indicated that those disoriented molecules and some disordered carbons were removed as volatiles or repacked into the glassy carbon structures during graphitization. The carbonized and graphitized phenolic resins were found to correspond to low order sp² bonded carbon, but cannot be considered as truly glassy or amorphous carbon materials since they have some degree of order in the basal plane.     

New polymer syntheses. IX. Synthesis and properties of new conducting polyazomethine polymers containing main chain cycloalkanone and pyridine moieties

Novel polyazomethines containing cycloalkanones or pyridine moieties were synthesized by the polycondensation of 2,5‐bis(m‐aminobenzylidene)cyclopentanone (BMAP, IV), 2,6‐bis(m‐aminobenzylidene)cyclohexanone (BMAH, V), 2,6‐bis(p‐aminobenzylidene)cyclohexanone (BPAH, VI), and 2,6‐bis(m‐aminostyryl)pyridine (BMAS, VIII) diamines with terephthalaldehyde in EtOH at 25°C. These polymers were yellow to orange in color, had reduced viscosities up to 1.42 dL/g, and had electric conductivities as high as 10⁻¹¹–10⁻¹² S cm⁻¹. All the polyazomethines were insoluble in common organic solvents but dissolved completely in concentrated sulfuric acid. However, they were readily hydrolyzed in concentrated H₂SO₄. X‐ray diffraction diagrams showed that the crystallinities of the polyazomethines were low. These azomethine polymers showed high thermal and thermooxidative stability and exhibited no appreciable decomposition up to 400°C in air. The electronic spectra of the polymers indicated a large bathochromic shift of the π–π* absorption band (∼360 nm) that was due to the presence of CN bonds in the polymer main chain. Doping with iodine dramatically raised the conductivity and produced dark brown to black colored semiconductive polymers with a maximum conductivity on the order of 10⁻⁷ S cm⁻¹. Furthermore, the morphology of selected examples of the four polyazomethines was examined by scanning electron microscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1218–1229, 2000     

Metal–Fluorocarbon Pyrolants: X. Influence of Ferric Oxide/Silicon Additive on Burn Rate and Radiometric Performance of Magnesium/Teflon/Viton® (MTV)

Both burn rate, u (mm s⁻¹) and mass consumption rate, (g s⁻¹ cm⁻²) of fuel rich magnesium/Teflon/Viton^® (MTV) (45/50/5) upon addition of silicon/ferric oxide for part of the PTFE decrease by 16 and 11%, respectively. However, the spectral efficiency E_β (J g⁻¹ sr⁻¹) increases by 24% in the 3–5 μm band.     

Generation of a low temperature NO linkage isomer in a transition metal complex of group 9: K[IrCl5NO]

The [IrCl₅NO]^− 1 ion in the potassium salt can be partially transformed into a metastable state by light irradiation in the violet-near UV region at low temperature (77 K). The excitation process was followed by infrared spectroscopy, comparing the spectra before and after irradiation.A new band grew at 1812 cm^− 1 after irradiation with light in the 308–420 nm spectral region. The metastable state behavior is verified as this band decays upon heating the samples above 90 K or by subsequent irradiation using 450–680 nm light. The band at 1812 cm^− 1 was assigned to ν(NO) of metastable state 1 (or an IrON linkage isomer) for comparison with the band position reported for other transition metal nitrosyls. To our knowledge, this is the first generation of a M-ON linkage isomer reported for a nitrosyl of transition metal of group 9. Its behavior is similar to that observed in other nitrosyl complexes of group 8.     

NO Adsorption on Ex-Framework [Fe,X]MFI Catalysts: Novel IR Bands and Evaluation of Assignments

IR spectra of NO adsorbed on isomorphously substituted [Fe,Al]MFI, [Fe,Ga]MFI and [Fe]MFI after steaming at 873 K in 30 vol% H₂O are presented. On ex-[Fe,Al]MFI, NO adsorption leads to bands at 2133 cm^-1 and a doublet at 1886 and 1874 cm^-1. The 2133 cm^-1 band is assigned to NO⁺ occupying cationic positions in the zeolite structure. Of the doublet, the 1874 cm^-1 band is much more susceptible to reaction with O₂ than the 1886 cm^-1 band, yielding adsorbed NO₂ with an absorption frequency of 1635 cm^-1. After evaluation of the constitution of the catalyst and (sometimes contradictory) literature assignments, the 1886 cm^-1 band is assigned to NO adsorbed on Fe ions located in isolated positions, and/or (FeO)_n clusters inside the zeolite channels, whereas the 1874 cm^-1 band is proposed to be induced by 2 nm FeAlO_x nano-particles. The ex-[Fe,Ga]MFI catalyst showed a similar absorption pattern (doublet), which is shifted to lower wavenumbers (1881 and 1867 cm^-1), suggesting that both frequencies are affected by the vicinity of Ga (or Al) to the Fe site involved. The absence of bands at 1765 and 1835 cm^-1 suggests that the isolated sites causing these absorptions are in the Fe^III state in ex-[Fe,Al]MFI and ex-[Fe,Ga]MFI. For the ex-[Fe]MFI sample, which did not contain any 2 nm FeO_x nano-particles, an NO absorption band at 1854 cm^-1 is assigned to mono-nitrosyl on extra-framework oligonuclear (Fe^IIO)_n species in the zeolite channels.     

Influence of inversion level on the optical absorption spectra of Ti-doped transparent MgGa2O4 ceramics

Ti-doped (0.08, 0.30, and 1.00 atomic% [at.%]) transparent MgGa₂O₄ ceramics (possessing a high inversion level; i up to 0.8) were fabricated by pulsed electric current sintering, at 950°C, under vacuum for 30–90 min. Optical transmission, emission, and electron paramagnetic resonance spectra were recorded. The maximal transmission level was ∼70% (820 nm), for a thickness of ∼1 mm, which, while not very high, permitted the observation of the optical absorption bands location and profile. Interpretation of the fluorescence spectra suggests that some Ti⁴⁺ cations (mostly hexacoordinated) were accommodated by the host despite the scarcity of oxygen in the atmosphere during the sintering process. The Ti³⁺ cations substitute native ions located in tetrahedral sites, distorting the original T_d symmetry toward a D_2d symmetry. Comparing the Ti-doped MgGa₂O₄ (high inversion) and MgAl₂O₄ (low inversion) spinels, spectral characteristics revealed that a significant increase in the inversion level drives Ti³⁺ cations from octahedral toward tetrahedral sites. This is reflected in the optical absorption spectra by the disappearance of the band at ∼20 000 cm⁻¹ (detectable in MgAl₂O₄) in MgGa₂O₄; the two d–d bands, of MgA₂O₄, in MgGa₂O₄ are reduced to a single one, located at 11 800 cm⁻¹. These results, for MgGa₂O₄, strongly support a similar assignment—of the strong band at 12 800 cm⁻¹, in Ti-doped MgAl₂O₄—to a tetracoordinated Ti³⁺. Thus, while in MgAl₂O₄, Ti³⁺ appears in both octahedral and tetrahedral coordination and in MgGa₂O₄ only the latter state is stable. In both spinels, Ti dopant speciates into Ti³⁺ and Ti⁴⁺ cations.     

Characterization of ethylene in EP and in iPP/EP systems by deconvolution of IR spectra

The purpose of this study is to propose a correlation between IR spectra and molecular structure of ethylene‐propylene (EP) copolymers possibly blended with isotactic polypropylene (iPP). The method is based on the deconvolution of the spectrum in the CH₂‐rocking range, i.e., 800–680 cm⁻¹, where the bands of interest overlap. The six bands present in this region were signal averaged in position and width. The spectra were then deconvoluted (curve fitted) assuming a Lorentzian shape for the bands. The band at 1167 cm⁻¹ (with a shoulder at 1156 cm⁻¹) corresponding to a CH₃ vibration is considered as an internal standard. The method was checked by varying some fitting parameters. In order to realize some quantitative measurements, calibration curves were established with some EP samples, characterized by ¹³C NMR, which were used as standards. The amounts of total  (CH₂ CH₂) units (ethylene units), isolated ethylene and structural defaults in PP were determined for different iPP/EP blends. Ethylene crystallinity has also been determined. A good correlation was evidenced between infrared and ¹³C NMR measurements. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 96–106, 2000     

Determination of density and birefringence of poly(ethylene terephthalate) fibers using Raman microscopy

Multiple regression analysis has been used to calibrate polarized Raman spectra of poly(ethylene terephthalate) fibers in terms of density and birefringence. The calibration spans PET fibers having a wide range of density and birefringence values. The calibration required the Raman spectrum in only one polarization direction, that is, with the polarization directions of the incident and scattered light parallel to each other and to the fiber axis. The peak at 631 cm⁻¹, which has been used previously as an internal standard band, could be used for the prediction of density, but not for the prediction of birefringence. The peak at 702 cm⁻¹ was found to be a good internal standard band for both density and birefringence. Density could be predicted with a standard error of prediction of 0.003 g/cc using only the ratio of the intensity of the band at 996 cm⁻¹ to that of 702 cm⁻¹ and the full width at half maximum of the 1725-cm⁻¹ band. Birefringence was predicted with a standard error of 0.01 using the ratios of the intensities of the bands at 996 and 1616 cm⁻¹ to that of the 702-cm⁻¹ band. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 943–952, 1999     

Raman scattering by defect-induced excitations in boron-doped diamond single crystals

Polarized Raman spectra of the oriented boron-doped diamond with a different content of boron (≤ 200 ppm) were obtained with 514.5 and 1064 nm excitations. The additional bands were found in the region below 1200 cm^− 1. Their intensity increased with doping. It was shown that in polarized spectra these bands were in agreement with the singularities of density of phonon states (DOS) of diamond for the A_1g, E_g and F_2g symmetries. It was assumed that the ~ 900 cm^− 1 band which does not coincide with any DOS peak and has the highest resonance character may be attributed to the localized mode of boron in a diamond lattice. The spectra were accompanied by continuum that had the same symmetry F_2g as optical phonon at 1333 cm^− 1.     

Sp3/sp2 character of the carbon and hydrogen configuration in micro- and nanocrystalline diamond

Hot filament and microwave plasma CVD micro- nanocrystalline diamond films are analysed by visible and ultra-violet excitation source Raman spectroscopy. The sample grain size varies from 20 nm to 2 μm. The hydrogen concentration in samples is measured by SIMS and compared to the grain size, and to the ratio of sp² carbon bonds determined by Raman spectroscopy from the 1332 cm^− 1 diamond peak and the sp² 1550 cm^− 1 G band. Hydrogen concentration appears to be proportional to the sp² bonds ratio. The 3000 cm^− 1 CH_x stretching mode band intensity observed on the Raman spectra is decreasing with the G band intensity. Thermal annealing modifies the sp² phase structure and concentration, as hydrogen outdiffuses.     

Subpicosecond Spectroscopy of Charge Separation in Rhodobacter capsulatus Reaction Centers

The time-evolution of the near-infrared absorption changes accompanying the conversion of the excited primary electron donor, P*, to the radical pair state, P⁺BPh_L⁻, has been examined in detail in Rhodobacter capsulatus reaction centers. In a series of spectra spanning the time interval from about 600 fs to 15 ps, two isosbestic points occurring at 765 run and 798 nm are maintained throughout. The finding of an isosbestic point at 798 nm in this series of spectra, which encompass the time during which P* decays and BPh_L⁻ forms, places severe constraints on the possible reduction of the 800-nm-absorbing monomeric BChl_L in the initial stage of the charge-separation process. The near-infrared P* spectrum, which is revealed clearly only when P is excited directly in its long-wavelength absorption band, contains bleaching only of the 855-nm band and a broad featureless transient absorption below 810 nm. This spectrum shows that P does not contribute any significant oscillator strength to the 800-nm ground state absorption band.     

Infrared study of the effect of heat on wool

The infrared spectra of wool heated in vacuum and in air to different temperatures ranging from 120 to 250°C were investigated. It was found that certain absorption bands disappear when wool is heated in vacuum to 180°C and in air to 120°C for 2 hr. Also, the results showed that the intensities of the C=O stretching band at 1660 cm⁻¹, N–H stretching band at 3325 cm⁻¹ and the C–H stretching band at 2940 cm⁻¹ decrease when wool is heated in vacuum to 180°C and in air to 120°C. The spectra of the samples heated in vacuum to 250°C and in air to 225°C exhibited strong absorption bands belonging to the carboxyl and sulfonate groups.     

Evolution of TiOx-SiOx nano-composite during annealing of ultrathin titanium oxide films on Si substrate

This paper discusses the formation of the TiO_x-SiO_x nano-composite phase during annealing of ultrathin titanium oxide films (~27 nm). The amorphous titanium oxide films are deposited on silicon substrates by sputtering. These films are important for high-k dielectrics and sensing applications. Annealing of these films at 750 °C in the O₂ environment (for 15–60 min) resulted in the polycrystalline rutile phase. The films exhibit Raman peaks at 150 cm⁻¹ (B_1g), 435 cm⁻¹ (E_g), and 615 cm⁻¹ (A_1g) confirming the rutile phase. The signature TO (1078 cm⁻¹) and LO (1259 cm⁻¹) infrared active vibrational modes of Si–O–Si bond confirms the presence of silicon-oxide. The X-ray photoelectron spectra of the TiO_x films show multiple peaks corresponding to Ti metal (453.8 eV); Ti⁴⁺ state (458.3 eV (Ti 2p_3/2) and 464 eV (Ti 2p_1/2)); and Ti³⁺ state (456.4 eV (Ti 2p_3/2) and 460.8 eV (Ti 2p_1/2)). The O1s XPS spectra peaks at 530–533 eV can be attributed to Ti–O and Si–O bonds of the TiO_x-SiO_x nano-composite phase in the annealed films. The depth profiling XPS study shows that the top surface of the annealed film is mainly TiO_x and the amount of SiO_x increases with the depth.     

Structural changes and crystallization kinetics of polylactide under CO2 investigated using high‐pressure Fourier transform infrared spectroscopy

The structural changes and crystallization kinetics of polylactide (PLA) during cold crystallization under CO₂ at 80 °C were studied using in situ high‐pressure Fourier transform infrared (FTIR) spectroscopy. The FTIR spectra show that PLA can crystallize under air and CO₂, and some differences are observed. In the second‐derivative spectra, the 1220 cm^?1 band is only found for PLA crystallized under CO₂, and the tt conformer of PLA crystallized under CO₂ is located at 1749 cm^?1, while that of PLA crystallized under air is located at 1751 cm^?1. From wide‐angle X‐ray diffraction, only the α′‐crystal is observed when PLA is crystallized under air, whereas the α‐crystal appears when crystallized under CO₂. The crystalline‐sensitive bands at 921 and 1458 cm^?1 were used to analyze the crystallization kinetics of PLA. When PLA crystallizes under air, the 1458 cm^?1 band changes faster than the 921 cm^?1 one; when it crystallizes under CO₂, the result reverses. This suggests that CO₂ hinders interchain interactions while promoting the helix conformation. © 2015 Society of Chemical Industry     

The correlation between surface conductivity and adsorbate coverage on diamond as studied by infrared spectroscopy

A high-resolution analysis of CH vibrational modes on a single crystal diamond(100) surface using Fourier-transform infrared (FTIR) spectroscopy in combination with conductivity measurements is reported. On a plasma-hydrogenated diamond(100) surface, the IR spectra measured in the multiple internal reflection mode reveal three absorption lines. Two of them at 2921 and 2854 cm⁻¹ vanish in air at an annealing temperature of 190°C and are assigned to the antisymmetric and symmetric CH₂ stretching modes of a physisorbed hydrocarbon species, respectively. The third band at 2897 cm⁻¹ has a width of 16 cm⁻¹, is stable up to 230°C and is associated with the stretching frequency of C₂H₂ monohydride units on the C(100) 2×1:2H surface. Upon annealing in air at temperatures lower than 200°C, the surface conductivity is reversibly reduced by up to five orders of magnitude. After cooling down to room temperature, it recovers the value of 1×10⁻⁵ Ω⁻¹ measured immediately after the plasma hydrogenation with a time constant of several days. Annealing at 230°C destroys the surface conductivity irreversibly and yields conductance values below the measurement limit of 5×10⁻¹² Ω⁻¹. We show that the chemisorbed hydrogen in the C₂H₂ configuration, together with at least one physisorbed species, is responsible for the surface conductivity of hydrogen-terminated diamond(100).     

Comparison of dissolution and mutual diffusion coefficients during dissolution of poly(methyl methacrylate) films

Steady state fluorescence measurements have been used for studying the dissolution of polymer films. These films are formed by free radical polymerization of methyl methacrylate (MMA) in which pyrene ( P_y ) was introduced as a fluorescence probe. Dissolution of poly(methyl methacrylate) (PMMA) films in chloroform–heptane mixtures were monitored in real-time by the P_y fluorescence intensity change. Dissolution coefficients D_d of P_y molecules were measured during dissolution of PMMA films, and found to be about 10⁻⁶ cm² s⁻¹. After dissolution, fluorescence quenching measurements were performed and the Stern–Volmer equation was employed to measure the mutual diffusion coefficients of heptane (D_h) and P_y (D_Py) molecules; these were found to be about 10⁻⁵ cm² s⁻¹. © 1999 Society of Chemical Industry     

Effect of hydrogen‐bonding in the development of high‐affinity metal ion complexants: Polymer‐bound phosphorylated cyclodextrin

In a series of phosphorylated polyols bound to a polystyrene support, the position of the FTIR band assigned to hydrogen bonding between the  OH and phosphoryl oxygen correlates with the affinity of that phosphoryl oxygen for metal ions. Polymer with phosphorylated β‐cyclodextrin (pCD) ligands is now reported as a further test of this correlation. The metal ion affinity is probed with the uranyl ion. pCD is the most red‐shifted of a series of five phosphorylated polyols: the strongest polyol had been phosphorylated pentaerythritol (pPE) with a band at 873 cm⁻¹; pCD has a band at 868 cm⁻¹. Consistent with the FTIR bands, pCD has a significantly higher affinity for the uranyl ion than pPE: the percents complexed from a 10⁻⁴M uranyl solution in a background of 1.0N HNO₃, HCl, and H₂SO₄ are 94.7%, 90.5%, and 93.6%, respectively, for pCD and 68.6%, 52.1%, and 40.1%, respectively, for pPE. This further supports the hypothesis that the strong complexing ability of phosphorylated polyols is due to activation of the phosphoryl oxygen through hydrogen bonding between the PO and the  OH groups within the polyol. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011