Effect of microstructure on hydrolytic degradation studies of poly (l-lactic acid) by FTIR spectroscopy and differential scanning calorimetry

Structural changes during thermally induced crystallization and alkaline hydrolysis of Poly(l-lactic acid) (PLLA) films were investigated using differential scanning calorimetry (DSC), FTIR spectroscopy, weight loss, HPLC and optical microscopy. It was shown that crystallinity (χ_c), glass transition temperature (T_g) and melting temperature (T_m) were found to be strongly annealing temperature (T_a) dependent. The FTIR study of PLLA films suggested that the bands at 921 and 956 cm⁻¹ could be used to monitor the structural changes of PLLA. An independent infrared spectroscopic method was developed for the first time to determine crystallinity of PLLA before degradation and it showed good qualitative correlation with DSC crystallinity. The higher crystallinity values determined by FTIR were attributed to the intermediate phase included in the IR crystallinity. Both the weight loss data and the percentage of lactic acid obtained by HPLC showed that the alkaline hydrolysis of PLLA films increased with increasing crystallinity. The DSC observation showed an increase in T_g and no significant change in T_m and heat of fusion, while IR showed an increase in IR crystallinity with increasing hydrolysis time. The increase in IR crystallinity and T_g with hydrolysis time suggested that degradation progressed from the edges of the crystalline lamellas without decreasing lamellar thickness, but increased the intermediate phase and the short-range order.     

Spreading and compression of n-hexadecyl acrylate at liquid-air interface

Usingn-hexadecyl acrylate, surface pressure-area (F-A) curves and equilibrium spreading pressuresF ^e were measured at various temperatures (5.7°–46°C) by the Langmuir balance (F-A) and the Wilhelmy-plate method (F ^e). At low temperatures (T<13 °C) condensed films and the liquid-condensed/solid condensed transition can be observed. At high temperatures (T>30 °C) liquid-expanded films occur. In the intermediate range the compression curves have two transition points. The transition pressureF ₁ between liquid-expanded and condensed film has a marked temperature dependence. The transition enthalpiesH ₁ decrease with increasing temperature and become zero at 29.2 °C. The second transition is related to a transition between the condensed films (F ₂). The slight temperature dependence of this transition is accompanied by an increasing change of area as well as by increasing transition enthalpiesH ₂.TheF ^e-T curve has two distinct breaks, at the melting pointT _m and atT=30 °C. The break atT _m is due to the melting process and the break atT=30 °C is caused by a phase transition between a liquid-expanded film and a condensed film.The phase diagram was constructed from the transition pressures. It can be demonstrated that the highest pressures of the thermodynamic stable film occurs atT _m. At temperaturesT>T _m equilibrium spreading pressure and equilibrium collapse pressure are identical whereas atT _m supercompression of the monolayer occurs. The film in this state behaves like a supercooled liquid. Obviously, rupture and collapse of such a film lead to a thermodynamically metastable bulk phase.     

Electrochemical Characterization of Myoglobin‐Polylysine Films at a Temperature Range of 6–80 °C

This work demonstrated for the first time that myoglobin cross‐linked in polylysine films is electrochemically active at 6 °C. At 6 °C, these protein films exhibited reversible reduction/oxidation peaks which are characteristic of Fe^III/Fe^II redox couple. The estimated current function densities (J=1.6×10^?4 C/V cm²), surface concentrations (Γ_T=0.10 nmol/cm²) and standard electron transfer constant (k_s=13.86 s^?1) at 6 °C for the data taken at a scan rate of 0.1 V/s were similar to those which were obtained at 10, 15 and 23 °C. Basically, this study shows a possible electrocatalytic application of these myoglobin/polylysine films, for example in low temperature sensing applications.     

Sustainable poly(ether amide)s from lignin-derived precursors

In recent years, there have been concerted efforts to replace petrochemical products with those from renewable sources due to the unsustainability of petroleum feedstock, and the continued volatility in the price. This work describes the synthesis and thermal properties of two new lignin-derived poly(ether-amide)s as alternative thermoplastics to petroleum-based commodities. Poly-4-(2-aminoethoxy)benzoate (PEAB) and poly-4-(2-aminoethoxy)-3-methoxybenzoate (PEAV) are synthesized by a melt polycondensation and characterized by ¹H NMR spectroscopy and thermal analysis. The number average molecular weight (M_n) of the polymers are estimated from the ¹H NMR spectroscopy analysis, and were shown to be 4100 and 12,000 g/mol for PEAB and PEAV respectively. The PEAB had a higher decomposition temperature (T_d) as well as glass transition temperature (T_g) compared to PEAV; albeit, with a lower molecular weight. The polymers’ T_d were in the range of 330 °C–380 °C and the T_g were between 100 °C and 120 °C. The thermal properties of the polymers are in the desirable range for thermoplastic materials used in the packaging, storage, and coating industries. Furthermore, the polymers are susceptible to degradation under acidic conditions in a short period; a property that is highly desirable for degradable polymers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2154–2160     

A photon transmission study for film formation from poly(vinyl acetate) latex particles with different molecular weights

The photon transmission technique was used to monitor the temperature evolution of film formation from poly(vinyl acetate) (PVAc) latex particles with two different molecular weights. Two sets of latex films were prepared below the glass transition temperature (T_g) of PVAc, which are named as low (LM) and high molecular weight (HM) films. These films were annealed at elevated temperatures above the T_g of PVAc for various time intervals. It is observed that transmitted photon intensity (I_tr) from these films increased as the annealing temperature was increased. Onset temperatures (T_H) at given times (τ_H) for starting the optical clarity of LM and HM films were measured and used to calculate the healing activation energies (ΔH) for the PVAc minor chains, and found to be as 28.1 kcal/mol and 27.7 kcal/mol, respectively. The increase in the transmitted photon intensity, I_tr above T_H was attributed to the increase in the number of disappeared interfaces between the deformed latex particles. Prager–Tirrell (PT) model was employed to interpret the increase in the crossing density of chains at the junction surfaces. The interdiffusion (backbone) activation energies (ΔE) were measured and found to be 177.5 kcal/mol and 210.7 kcal/mol for a diffusing PVAc chains across the junction surface of LM and HM latex films, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2918–2925, 2007     

Lamellar thickening in nascent poly(acrylonitrile) upon annealing

No systematic study has been reported on the lamellar thickening in atactic poly(acrylonitrile) (PAN) upon annealing because PAN, in the form of solution‐cast films or their drawn products, generally shows no small‐angle X‐ray scattering (SAXS) maximum corresponding to the lamellar thickness. In this work, PAN crystals were precipitated during the thermal polymerization of acrylonitrile in solution. The nascent PAN film, obtained by the filtration of the crystal suspension, exhibited a clear SAXS maximum revealing the lamellar structure. The lamellar thickening upon annealing of the nascent PAN films was studied in the temperature range 100–180 °C, where the degradation was minimal, as confirmed by the absence of an IR absorption band at 1605 cm⁻¹ ascribed to the cyclized nitrile groups. Above 190 °C, the degradation of the samples was significant, and the SAXS became too broad to determine the scattering maximum. The long period was significantly affected by the annealing time (t_a) and the temperature (T_a). Depending on t_a, three stages were observed for the lamellar thickening behavior. The lamellar thickness stayed constant in stage I (t_a = 0.5–3 min, depending on T_a), rapidly increased in stage II (t_a = 0.5–8 min), and stayed at a constant value characteristic for each T_a at yet longer t_a's in stage III. The lamellar thickness characteristic for T_a increased rapidly with increasing T_a at 165 °C (or higher), which was 152 °C lower than the estimated melting temperature of PAN (T_m = 317 °C). A possible mechanism for such lamellar thickening in PAN far below the T_m is discussed on the basis of the enhanced chain mobility in the crystalline phase above the crystal/crystal reversible transition at 165–170 °C detected by differential scanning calorimetry and wide‐angle X‐ray diffraction. The structural changes associated with annealing are also discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2571–2579, 2000     

Effect of end group chemistry on surface molecular motion of monodisperse polystyrene films

The surface molecular motion of monodisperse polystyrene (PS) with various chain end groups was investigated on the basis of temperature‐dependent scanning viscoelasticity microscope (TDSVM). The surface glass transition temperatures, T_g^ss for the proton‐terminated PS (PS‐H) films with number‐average molecular weight, M_n of 4.9k–1,450k measured by TDSVM measurement were smaller than those for the bulk one, with corresponding M_ns, and the T_g^ss for M_n smaller than ca. 50k were lower than room temperature (293 K). In the case of M_n = ca. 50k, the T_g^ss for the α,ω‐diamino‐terminated PS (α,ω‐PS(NH₂)₂) and α,ω‐dicarboxy‐terminated PS (α,ω‐PS(COOH)₂) films were higher than that of the PS‐H film. On the other hand, the T_g^s for the α,ω‐perfluoroalkylsilyl‐terminated PS (α,ω‐PS(SiC₂C^F₆)₂) film with the same M_n was much lower than those for the PS films with all other chain ends. The change of T_g^s for the PS film with various chain end groups can be explained in terms of the depth distribution of chain end groups at the surface region.     

Segmental and crosslink point motion in networks

¹³C- and ³¹P-NMR spin lattice relaxation in the rotating frame have been measured on a series of networks prepared from monodisperse and deliberately bimodal poly(propylene glycols) (PPG) crosslinked with tris(4-isocyanatophenyl) thiophosphate. The T_1pC minima correspond to loss maxima in the DMTA (Dynamic Mechanical Testing) measured at 10Hz. The T_1p^P minima fall at higher temperatures than those of T_1p^C for the same network indicating that these crosslinks lag the segments in frequency of motion at a given temperature. The carbon relaxation is biphasic below T_g of the segments indicating two relaxation domains which we assign to bulklike PPG segments and PPG segments proximal to he crosslink. Lineshape analysis by a diffusional model indicates crosslink reorientation is not isotropic until well above T_g. Relaxation and lineshapes for the bimodal networks indicate that junctions are not uniformly plasticized by the segments.     

Effect of nanoscale confinement on the glass transition temperature of free-standing polymer films: Novel,self-referencing fluorescence method

The effect of nanoscale confinement on the glass transition temperature, T_g, of freely standing polystyrene (PS) films was determined using the temperature dependence of a fluorescence intensity ratio associated with pyrene dye labeled to the polymer. The ratio of the intensity of the third fluorescence peak to that of the first fluorescence peak in 1-pyrenylmethyl methacrylate-labeled PS (MApyrene-labeled PS) decreased with decreasing temperature, and the intersection of the linear temperature dependences in the rubbery and glassy states yielded the measurement of T_g. The sensitivity of this method to T_g was also shown in bulk, supported PS and poly(isobutyl methacrylate) films. With free-standing PS films, a strong effect of confinement on T_g was evident at thicknesses less than 80–90 nm. For MApyrene-labeled PS with M_n = 701 kg mol⁻¹, a 41-nm-thick film exhibited a 47 K reduction in T_g relative to bulk PS. A strong molecular weight dependence of the T_g-confinement effect was also observed, with a 65-nm-thick free-standing film exhibiting a reduction in T_g relative to bulk PS of 19 K with M_n = 701 kg mol⁻¹ and 31 K with M_n = 1460 kg mol⁻¹. The data are in reasonable agreement with results of Forrest, Dalnoki-Veress, and Dutcher who performed the seminal studies on T_g-confinement effects in free-standing PS films. The utility of self-referencing fluorescence for novel studies of confinement effects in free-standing films is discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2754–2764, 2008     

Kinetics of the reactions of Cl(2PJ) and Br(2P3/2) with O3

A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of the important stratospheric reactions Cl(²P_J) + O₃ → ClO + O₂ and Br(²P_3/2) + O₃ → BrO + O₂ as a function of temperature. The temperature dependence observed for the Cl(²P_J) + O₃ reaction is nonArrhenius, but can be adequately described by the following two Arrhenius expressions (units are cm³ molecule^?1 s^?1, errors are 2σ and represent precision only): ??₁(T) = (1.19 ± 0.21) × 10^?11 exp [(?33 ± 37)/T] for T = 189–269K and ??₁(T) = (2.49 ± 0.38) × 10^?11 exp[(?233 ± 46)/T] for T = 269–385 K. At temperatures below 230 K, the rate coefficients determined in this study are faster than any reported previously. Incorporation of our values for ??₁(T) into stratospheric models would increase calculated ClO levels and decrease calculated HCl levels; hence the calculated efficiency of ClO_x catalyzed ozone destruction would increase. The temperature dependence observed for the (²P_3/2) + O₃ reaction is adequately described by the following Arrhenius expression (units are cm³ molecule^?1 s^?1, errors are 2σ and represent precision only): ??₂(T) = (1.50 ± 0.16) × 10^?1 exp[(?775 ± 30)/T] for T = 195–392 K. While not in quantitative agreement with Arrhenius parameters reported in most previous studies, our results almost exactly reproduce the average of all earlier studies and, therefore, will not affect the choice of ??₂(T) for use in modeling stratospheric BrO_x chemistry.     

Solvent Electrostatic and Covalent Effects on Complexation Thermodynamics

A new method is suggested for estimating the electrostatic and covalent contributions to the standard Gibbs energy, enthalpy and entropy of complexation reactions upon transfer from water (W) to non-aqueous and mixed aqueous organic solvents (S). The equations derived for calculation of the electrostatic (temperature dependent) contributions are based on the temperature dependences of thermodynamic parameters of complexation in aqueous solution and the temperature dependence of the dielectric constant of water. These contributions correspond to the transfer process in water from T₁ = 298.15 K to a higher temperature (T₂) at which water has the same dielectric constant as does the solvent S at 298.15 K (εW(T₂) = εS(T₁)). The covalent (temperature independent) contributions are calculated at isodielectric conditions (transfer from water at T₂ to S at T₁) using the corresponding thermodynamic cycle. Application of the model to an analysis of solvent effects is demonstrated and discussed with an example given of a typical complexation reaction between K⁺ and 18-crown-6 in pure non-aqueous and water-acetonitrile mixed solvents.     

Rate coefficients for the reactions of OH with butanols from 298 K to temperatures relevant for low-temperature combustion

Rate coefficients for the reactions of OH with n, s, and iso-butanol have been measured over the temperature range 298 to ∼650 K. The rate coefficients display significant curvature over this temperature range and bridge the gap between previous low-temperature measurements with a negative temperature dependence and higher temperature shock tube measurements that have a positive temperature dependence. In combination with literature data, the following parameterizations are recommended: k_{1,OH + n-butanol}(T) = (3.8 ± 10.4) × 10⁻¹⁹T^{2.48 ± 0.37}exp ((840 ± 161)/T) cm³ molecule⁻¹ s⁻¹ k_{2,OH + s-butanol}(T) = (3.5 ± 3.0) × 10⁻²⁰T^{2.76 ± 0.12}exp ((1085 ± 55)/T) cm³ molecule⁻¹ s⁻¹ k_{3,OH + i-butanol}(T) = (5.1 ± 5.3) × 10⁻²⁰T^{2.72 ± 0.14}exp ((1059 ± 66)/T) cm³ molecule⁻¹ s⁻¹ k_{4,OH + t-butanol}(T) = (8.8 ± 10.4) × 10⁻²²T^{3.24 ± 0.15}exp ((711 ± 83)/T) cm³ molecule⁻¹ s⁻¹ Comparison of the current data with the higher shock tube measurements suggests that at temperatures of ∼1000 K, the OH yields, primarily from decomposition of β-hydroxyperoxy radicals, are ∼0.3 (n-butanol), ∼0.3 (s-butanol) and ∼0.2 (iso-butanol) with β-hydroxyperoxy decompositions generating OH, and a butene as the main products. The data suggest that decomposition of β-hydroxyperoxy radicals predominantly occurs via OH elimination.     

Electrochromic properties of MoO<Subscript>3</Subscript> thin films derived by a sol–gel process

Molybdenum trioxide (MoO₃) films were deposited on ITO/Glass substrates by the sol–gel method using a spin-coating technique and heat treated at various temperatures under different ambient atmosphere. Effects of the process parameters on the electrochromic properties of MoO₃ films were studied using cyclic voltammetry (CV) in a propylene carbonate (PC) non-aqueous solution containing 1 M lithium perchlorate (LiClO₄). Electrochromic MoO₃ film on lithium intercalation was investigated by in-situ transmittance measurement during the CV process. The MoO₃ films showed reversible recharge ability on Li⁺/e⁻ intercalation/deintercalation. Experimental results revealed that the heat-treatment temperature, the ambient atmosphere, and the thickness will have the string influence on the electrochromic properties of MoO₃ thin films. X-ray diffraction (XRD) results show that the amorphous MoO₃ films can be obtained with the heat-treatment temperature below 300 °C in O₂ ambient atmosphere. The optimum electrochromic MoO₃ film, with a thickness of 130 nm, exhibits a maximum transmittance variation (ΔT%) of 30.9%, an optical density change (ΔOD) of 0.213, an intercalation charge (Q) of 8.47 mC/cm², an insertion coefficient x in Li _x MoO₃ was 0.21 and a coloration efficiency (η) of 25.1 cm²/C between the colored and bleached states at a wavelength (λ) of 550 nm.     

Oxygen barrier properties of organic montmorillonite modified polyamide 11/Poly (vinyl alcohol) films

Organic montmorillonite (OMMT) nano‐platelets were exfoliated and well dispersed in fully bio‐based polyamide 11/Poly(vinyl alcohol) (PA11/PVA) blends. Significantly lower oxygen permeation rates (OTR) were detected for the PA11_72.5PVA_27.5OMMT_x films than those of PA11 and PA11_72.5PVA_27.5 films. An extremely low OTR of 0.218 cm³/m²·day·atm was found for PA11_72.5PVA_27.5OMMT₁ film modified with 1 PHR optimum concentration of well dispersed OMMT nano‐platelets. Similarly, the free volume characteristics evaluated for PA11_72.5PVA_27.5OMMT_x film series reduced to a minimum as the OMMT concentration reached the optimum value. As revealed by dynamic mechanical and differential scanning calorimetric analyses of PA11_72.5PVA_27.5OMMT_x film series, all dynamic glass transition temperature (T_g), melting temperature (T_m) and percentage crystallinity (W_c) values of PA11_72.5PVA_27.5OMMT_x films were noticeably higher than those of PA11_72.5PVA_27.5 film without addition of OMMT. In fact, T_gs, T_ms and W_cs evaluated for PA11_72.5PVA_27.5OMMT_x films increased to a maximum, as their OMMT reached the optimum concentration. The considerably enhanced oxygen barrier resistance found for PA11_72.5PVA_27.5OMMT_x films was ascribed to the considerably reduced free volume characteristics and much longer permeation path caused by impermeably OMMT nano‐platelets well dispersed in PA11_72.5PVA_27.5OMMT_x films.     

Kinetic and thermodynamic analysis of degradation of doripenem in the solid state

The kinetic and thermodynamic parameters of degradation of doripenem were studied using a high‐performance liquid chromatography method. In dry air, the degradation of doripenem was a first‐order reaction depending on the substrate concentration. At increased relative air humidity, doripenem was degraded according to the autocatalysis kinetic model. The dependence ln k = f1/T) was described by the equations ln k = 5.10 ± 13.06 ? (7576 ± 4939)(1/T) in dry air and ln k = 46.70 ± 22.44 ? (19,959 ± 8031)(1/T) at 76.4% relative humidity (RH). The thermodynamic parameters E_a, ΔH^≠a, and ΔS^≠a of the degradation of doripenem were calculated. The dependence ln k = f (RH%) was described by the equation ln k = (0.155 ± 0.077) × 10^?1 (RH%) ? (3.45 ± 21.8) × 10^?10. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 722–728, 2012     

One-pot Synthesis and Characterization of Poly(meta-aryl sulfide sulfone imide imide)

Poly(meta-aryl sulfide sulfone imide imide) (m-PASSII) was synthesized by one-pot process using 4-chlorophthalic anhydride, 3,3′-diamino diphenyl sulfone and sodium sulfide (Na₂S· xH₂O) as starting materials in N-methyl-2-pyrrolidone at atmospheric pressure. The intrinsic viscosity of m-PASSII was obtained with optimum synthesis conditions is 0.21-0.27 dl/g. The polymer and the separated intermediates which generated during the synthesis process were characterized by elemental analysis, FT-IR spectrum, ¹H-NMR spectrum, X-ray diffraction, DSC, TGA and dissolvability experiment. The polymer is found to have excellent thermal performance with glass transition temperature (T _g ) of 224°C and initial degradation temperature (T _d ) of 441°C. Moreover, the polymer is dissolvable in strong polar solvents.     

Investigation on LCST behavior of a new amorphous/crystalline polymer blend: Poly(n‐methyl methacrylimide)/poly(vinylidene fluoride)

The liquid–liquid phase‐separation (LLPS) behavior of poly(n‐methyl methacrylimide)/poly(vinylidene fluoride) (PMMI/PVDF) blend was studied by using small‐angle laser light scattering (SALLS) and phase contrast microscopy (PCM). The cloud point (T_c) of PMMI/PVDF blend was obtained using SALLS at the heating rate of 1 °C min^?1 and it was found that PMMI/PVDF exhibited a low critical solution temperature (LCST) behavior similar to that of PMMA/PVDF. Moreover, T_c of PMMI/PVDF is higher than its melting temperature (T_m) and a large temperature gap between T_c and T_m exists. At the early phase‐separation stage, the apparent diffusion coefficient (D_app) and the product (2Mk) of the molecules mobility coefficient (M) and the energy gradient coefficient (k) arising from contributions of composition gradient to the energy for PMMI/PVDF (50/50 wt) blend were calculated on the basis of linearized Cahn‐Hilliard‐Cook theory. The kinetic results showed that LLPS of PMMI/PVDF blends followed the spinodal decomposition (SD) mechanism. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1923–1931, 2008     

Theoretical study on the degradation mechanism of methamidophos and chloramine phosphorus with OH radicals

Theoretical investigation on the gas‐phase degradation reaction mechanism of methamidophos (MAP) and chloramine phosphorus (CHP) with OH radicals is performed. The equilibrium geometries and the harmonic vibration frequencies of the stationary points are obtained at M06‐2x/6‐31+G(d,p) level, and the higher‐level energetic information is further refined at M06‐2x/6–311++G(3df,2p) level. The rate constants for the 14 reaction channels are calculated by the improved canonical variational transition state theory with small‐curvature tunneling correction over the temperature range 200–2000 K. The three‐parameter expressions of k₁(T) = 1.53 × 10^?19T^2.74exp(?1005.12/T), k₂(T) = 1.36 × 10^?20T^3.02exp(?1259.56/T) are given. The total rate constants of all reaction channels of MAP with OH radicals are in good agreement with the available experimental data. Our results indicate that the H‐abstraction reactions on methyl are the major channels for the reaction of MAP and CHP with OH radicals. © 2015 Wiley Periodicals, Inc.     

Thermal properties of lignin-and molasses-based polyurethane foams

Lignin-and molasses-based polyurethane (PU) foams with various lignin/molasses mixing ratios were prepared. The hydroxyl group in molasses and lignin is used as the reaction site and PU foams with various isocyanate (NCO)/the hydroxyl group (OH) ratios were obtained. Thermal properties of PU foams were investigated by differential scanning calorimetry (DSC), thermogravimetry (TG) and thermal conductivity measurement. Glass transition temperature (T _g) was observed depending on NCO/OH ratio in a temperature range from ca. 80 to 120°C and thermal decomposition temperature (T _d) from ca. 280 to 295°C. Mixing ratio of molasses and lignin polyol scarcely affected the T _g and T _d. Thermal conductivity of PU foams was in a range from 0.030 to 0.040 Wm⁻¹ K⁻¹ depending on mixing ratio of lignin and molasses.     

Ab initio study of the OH + CH2O reaction: The effect of the OH··OCH2 complex on the H‐abstraction kinetics

Kinetics for the reaction of OH radical with CH₂O has been studied by single‐point calculations at the CCSD(T)/6‐311+G(3df, 2p) level based on the geometries optimized at the B3LYP/6‐311+G(3df, 2p) and CCSD/6‐311++G(d,p) levels. The rate constant for the reaction has been computed in the temperature range 200–3000 K by variational transition state theory including the significant effect of the multiple reflections above the OH··OCH₂ complex. The predicted results can be represented by the expressions k₁ = 2.45 × 10^‐21 T^2.98 exp (1750/T) cm³ mol^?1 s^?1 (200–400 K) and 3.22 × 10^‐18 T^2.11 exp(849/T) cm³ mol^?1 s^?1 (400–3000 K) for the H‐abstraction process and k₂ = 1.05 × 10^‐17 T^1.63 exp(?2156/T) cm³ mol^?1 s^?1 in the temperature range of 200–3000 K for the HO‐addition process producing the OCH₂OH radical. The predicted total rate constants (k₁ + k₂) can reproduce closely the recommended kinetic data for OH + CH₂O over the entire range of temperature studied. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 322–326, 2006