Synthesis and biological activity of phthalimide‐based polymers containing 5‐fluorouracil

The attachment of anticancer agents to polymers is a promising approach towards reducing the toxic side‐effects and retaining the potent antitumour activity of these agents. A new tetrahydrophthalimido monomer containing 5‐fluorouracil (ETPFU) and its homopolymer and copolymers with acrylic acid (AA) and with vinyl acetate (VAc) have been synthesized and spectroscopically characterized. The ETPFU contents in poly(ETPFU‐co‐AA) and poly(ETPFU‐co‐VAc) obtained by elemental analysis were 21 mol% and 20 mol%, respectively. The average molecular weights of the polymers determined by gel permeation chromatography were as follows: M_n = 8900 g mol^?1, M_w = 13 300 g mol^?1, M_w/M_n = 1.5 for poly(ETPFU); M_n = 13 500 g mol^?1, M_w = 16 600 g mol^?1, M_w/M_n = 1.2 for poly(ETPFU‐co‐AA); M_n = 8300 g mol^?1, M_w = 11 600 g mol^?1, M_w/M_n = 1.4 poly(ETPFU‐co‐VAc). The in vitro cytotoxicity of the compounds against FM3A and U937 cancer cell lines increased in the following order: ETPFU > 5‐FU > poly(ETPFU) > poly(ETPFU‐co‐AA) > poly(ETPFU‐co‐VAc). The in vivo antitumour activities of all the polymers in Balb/C mice bearing the sarcoma 180 tumour cell line were greater than those of 5‐FU and monomer at the highest dose (800 mg kg^?1). © 2002 Society of Chemical Industry     

Process Parametric Study for Ethene Carboxylic Acid Removal onto Powder Activated Carbon using Box‐Behnken Design

Ethene carboxylic acid removal from wastewater using powder activated carbon (PAC) requires a proper process parametric study to determine its optimal performance characteristics. Response Surface Methodology (RSM) is one of the advanced statistical analysis techniques for parametric studies involving a minimum number of trials. The Box‐Behnken surface statistical design of experiments was carried out with three factors, i.e., dose, w, temperature, T, and time of contact, t, between the ethene carboxylic acid and the adsorbent, while maintaining the ethene carboxylic acid concentration, C₀ = 100 mg/L, as a fixed input parameter. The performance of the Box‐Behnken design was analyzed and optimized using Design‐Expert software for ethene carboxylic acid removal onto adsorbent using a batch system. The higher values of the correlation coefficients, lack‐of‐fit greater than 4 and p values < 0.05 are in good agreement with the optimum combination of process parameters, which proves the fitness of the selected model for analyzing the experimental data.     

Preparation and characterization of poly(dimethyldiallylammonium chloride) with high molar mass using high purity industrial monomer

A preparation method for high molar mass poly(dimethyldiallylammonium chloride) (PDMDAAC) is reported in this article. PDMDAAC was prepared by using the high purity industrial grade dimethyldiallylammonium chloride (DMDAAC) monomer from one‐step method and ammonium persulphate (APS) as the initiator. The initiator was added all at once and the reaction temperature was increased stepwise to complete the polymerization gradually. The effects of several polymerization condition variables on the intrinsic viscosity value ([η]) and monomer conversion rate (Conv.) of product PDMDAAC were investigated, respectively. The variables included: T₁ (42.0 to 52.0°C), T₂ (47.5 to 57.5°C), T₃ (55.0 to 75.0°C), m(DMDAAC) (60.0 to 70.0%), m(APS) : m(DMDAAC) (0.25 to 0.45%), m(Na₄EDTA) : m(DMDAAC) (0 to 0.0071%). Under an optimum condition of T₁ = 46.0°C, T₂ = 52.5°C, T₃ = 65.0°C, m(DMDAAC) = 65.0%, m(APS) : m(DMDAAC) = 0.35%, m(Na₄EDTA) : m(DMDAAC) = 0.0035%, the maximum [η] of obtained product PDMDAAC reached 3.43 dL/g, at a Conv. of 100.00%. The M_w of the product measured with GPC‐MALLS was 1.034 × 10⁶, polydespersity M_w/M_n was 2.421, and the R_g was 60.3 nm. The structure and properties of products were characterized by FTIR and NMR. Thermal decomposition was determined by TGA‐DSC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and antitumour activity of medium molecular weight phthalimide polymers of camptothecin

Attachment of anticancer agents to polymers has been demonstrated to improve their therapeutic profiles. A new monomer containing camptothecin, 5‐norbonene‐endo‐2,3‐dicarboxylimidoundecanoyl‐camptothecin (NDUCPT) and its homopolymer and copolymer with acrylic acid (AA) were synthesized and spectroscopically characterized. The NDUCPT content in poly(NDUCPT‐co‐AA) obtained by elemental analysis was 51%. The average molecular weights of the polymers determined by gel permeation chromatography were as follows: M_n = 12 100, M_w = 23 400 g mol^?1, M_w/M_n = 1.93 for poly(NDUCPT), M_n = 15 400, M_w = 28 300 g mol^?1, M_w/M_n = 1.83 for poly(NDUCPT‐co‐AA). The IC₅₀ value of NDUCPT and its polymers against U937 cancer cells was larger than that of CPT. The in vivo antitumour activity of all polymers in Balb/C mice bearing the sarcoma 180 tumour cell line was greater than that of CPT at a dose of 100 mg kg^?1. Copyright © 2003 Society of Chemical Industry     

Isothermal cold crystallization and melting behaviors of poly(L‐lactic acid)s prepared by melt polycondensation

The isothermal cold crystallization and melting behaviors of poly(L ‐lactic acid)s (PLLAs, weight average molecular weight, M_w, 6000–80,000) prepared via melt polycondensation were studied with differential scanning calorimeter in this work. It is found that the crystallization rate increased with decreasing M_w, reached a maximum at M_w of ca. 21,000 and then decreased again. The crystallinity of PLLA can be controlled in the range 30–50% by crystallization temperature (T_c) and time to fulfill the requirement of subsequent solid state polycondensation. The melting behavior strongly depends on T_c. The samples crystallized at high T_c melted with a single peak but those crystallized at low T_c melted with double peaks. The higher melting point (T_mH) kept almost constant and the lower melting point (T_mL) increased clearly with T_c. But the T_mL changed in jumps and a triple melting peak appeared at the vicinity of a characteristic crystallization temperature T_b, possibly because of a change of crystal structure. The equilibrium melting temperature of PLLA with M_w of 21,300 was extrapolated to be 222°C with nonlinear Hoffman‐Weeks method. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and biological activity of medium range molecular weight polymers containing exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidocaproic acid

A new monomer, exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidocaproic acid (ETCA), was prepared by reaction of maleimidocaproic acid and furan. The homopolymer of ETCA and its copolymers with acrylic acid (AA) or with vinyl acetate (VAc) were obtained by photopolymerizations using 2,2‐dimethoxy‐2‐phenylacetophenone as an initiator at 25 °C. The synthesized ETCA and its polymers were identified by FTIR, ¹H NMR and ¹³C NMR spectroscopies. The apparent average molecular weights and polydispersity indices determined by gel permeation chromatography (GPC) were as follows: M_n = 9600 g mol^?1, M_w = 9800 g mol^?1, M_w/M_n = 1.1 for poly(ETCA); M_n = 14 300 g mol^?1, M_w = 16 200 g mol^?1, M_w/M_n = 1.2 for poly(ETCA‐co‐AA); M_n = 17 900 g mol^?1, M_w = 18 300 g mol^?1, M_w/M_n = 1.1 for poly(ETCA‐co‐VAc). The in vitro cytotoxicity of the synthesized compounds against mouse mammary carcinoma and human histiocytic lymphoma cancer cell lines decreased in the following order: 5‐fluorouracil (5‐FU) ≥ ETCA > polymers. The in vivo antitumour activity of the polymers against Balb/C mice bearing sarcoma 180 tumour cells was greater than that of 5‐FU at all doses tested. © 2001 Society of Chemical Industry     

In‐Situ Fiberized Poly(ethylene terephthalate) as a Reinforcement to Poly(propylene) Matrix

The reinforced poly(propylene) (PP)/poly(ethylene terephthalate) (PET) in‐situ fiberized composites were prepared by extrusion‐drawing‐injection molding. The influences of PET weight fraction (f_w) on the PET fiberization, phase morphology, and mechanical properties of the composites, together with their functional mechanisms were studied by contrast to the normal‐blended materials without drawing. The results show that as the f_w rises from 0 to 20%, the number of PET fibers increases, whereas their diameter and dispersity decrease till f_w = 15% and then increase, and the number of remained PET particles tends to rise. These changes of PET fiberization and phase morphology with f_w were attributed to the consequence of the combined actions of breakup, coalescence, and deformation of the PET dispersed phase in the PP matrix during the extrusion drawing. Correspondingly, the tensile strength (σ_t) and Young's modulus (E) of the in‐situ composites increase till f_w = 15% and then decrease, with maximum gains of σ_t and E of about 20 and 70% relative to the neat PP, respectively. This σ_t/f_w relation was ascribed to the counterbalanced result between the reinforcing effect of the dispersed phase on matrix and the interfacial flaw effect of two immiscible phases, while the E/f_w relation was considered as a representation of the rigidizing effect of the fibers on the matrix being controlled by both their number and diameter.

In‐situ PET fibres (PET/PP = 85/15) in an as‐drawn filament.     

Kinetics of organochlorine removal from bleached kraft pulp mill effluent during biological treatment

Batch biodegradation kinetic studies were conducted with various bleached kraft pulp mill effluents containing organically bound chlorine measured as adsorbable organic halogen (AOX) (6.0 - 35 mg Cl/L). Biomass, generated in both a continuous bench scale reactor and a mill scale activated sludge system, at various concentrations (0.4 - 3.1 g VSS/L) was added to various effluents (about 70% ClO₂ substitution). AOX removal kinetics were best described by a simple recalcitrant first order model: - dS/dt = k_s,1X(S-S_∞), where S and S_∞ are AOX concentrations (mg Cl/L) at time t and t_∞, respectively, k_s,1 is the AOX removal rate constant (L/g VSS.h) and X is the biomass concentration (g VSS/L). The model indicated a constant non-biodegradable fraction of AOX (0.4 mg of AOX per mg of influent AOX) and was able to predict the effect of dilution on AOX removal with a single value of k_s,1 (0.13 L /g VSS.h). The degradation constants (0.16 L /g VSS.h) in the absence of effluent from the neutral sewer (i.e. for a mixture of acidic and alkaline effluent only) were significantly higher than those for whole mill effluent.     

Stereocomplex formation between poly(L‐lactic acid) and poly(D‐lactic acid) with disproportionately low and high molecular weights from the melt

Poly(L ‐lactic acid) (PLLA) and poly(D ‐lactic acid) (PDLA) with very different weight‐average molecular weights (M_w) of 4.0 × 10³ and 7.0 × 10⁵ g mol^?1 (M_w(PDLA)/M_w(PLLA) = 175) were blended at different PDLA weight ratios (X_D = PDLA weight/blend weight) and their crystallization from the melt was investigated. The presence of low molecular weight PLLA facilitated the stereocomplexation and thereby lowered the cold crystallization temperature (T_cc) for non‐isothermal crystallization during heating and elevated the radial growth rate of spherulites (G) for isothermal crystallization, irrespective of X_D. The orientation of lamellae in the spherulites was higher for the neat PLLA, PDLA and an equimolar blend than for the non‐equimolar blends. It was found that the orientation of lamellae in the blends was maintained by the stereocomplex (SC) crystallites. Although the G values are expected to decrease with an increase in X_D or the content of high‐molecular‐weight PDLA with lower chain mobility compared with that of low‐molecular‐weight PLLA, G was highest at X_D = 0.5 where the maximum amount of SC crystallites was formed and the G values were very similar for X_D = 0.4 and X_D = 0.6 with the same enantiomeric excess. This means that the effect of SC crystallites overwhelmed that of chain mobility. The nucleating mechanisms of SC crystallites were identical for X_D = 0.1–0.5 in the T_c range 130–180 °C. Copyright © 2011 Society of Chemical Industry     

Study on conformational transition phenomena of poly(methyl methacrylate) in acetonitrile near theta conditions

The coil–globule transition for poly(methyl methacrylate) (PMMA) has been studied in a theta solvent, acetonitrile (Θ = 45 °C). The viscosity of PMMA was measured as a function of temperature in the range 26–55 °C. The contraction and expansion of the molecular chains are determined using the measured viscosity values. The temperature dependence of the intrinsic viscosity can be represented by a master curve in a versus |τ|M _w^1/2 (g^1/2 mol^−1/2) plot, where τ = |T − Θ|/T is the reduced temperature and M_w‐is the weight‐average molecular weight. A universal plot of reduced viscosity versus reduced blob parameter (N/N_c) shows the attainment of the collapsed state below the theta temperature. The dimensions of PMMA in acetonitrile (M_w = 3.15 × 10⁶ g mol⁻¹) decrease to 63 % at 26 °C of those in the unperturbed state. The results in this work are compared with those previously published. © 2000 Society of Chemical Industry     

Synthesis and characterization of a random terpolymer of L‐lactide, ϵ‐caprolactone and glycolide

A random terpolymer of L ‐lactide (LL), ?‐caprolactone (CL) and glycolide (G) has been synthesized in bulk at 130 °C using stannous octoate as the coordination–insertion initiator. The terpolymer, poly(LL‐ran‐CL‐ran‐G), has been characterized by a combination of analytical techniques: GPC, ¹H NMR, ¹³C NMR, DSC and TG. Molecular weight characterization by GPC shows a unimodal molecular weight distribution with values of M _n = 1.01 × 10⁵ g mol^?1 and M _w / M _n = 2.17. Compositional and microstructural analysis by ¹H NMR and ¹³C NMR, respectively, reveal a terpolymer composition of LL:CL:G = 74:15:11 (mol%) with a chain microstructure consistent with random monomer sequencing. This latter view is supported by the terpolymer temperature transitions (T_g and T_m) from DSC and the thermal decomposition profile from TG. The results and, in particular, the conclusion that it is a random rather than a statistical terpolymer are discussed in the light of current theories regarding the mechanism of this type of polymerization. © 2001 Society of Chemical Industry     

In-chain functionalization by alternating anionic copolymerization of styrene and 1-(4-dimethylaminophenyl)-1-phenylethylene

Anionic copolymerizations of styrene (M₁) with excess 1-(4-dimethyl-aminophenyl)-1-phenylethylene (M₂) were conducted in benzene at 25°C for 24h, using sec-butyllithium as initiator. Narrow molecular weight distribution copolymers with M?;_n = 16.1 × 10³ g/mol (M?_w/M?_n = 1.04) and 38.2 × 10³g/mol (M?_w/M?_n = 1.05), and 24 and 38 moles of M₂ per macromolecule, respectively, were characterized by size exclusion chromatography, ¹H NMR spectroscopy and DSC. The monomer reactivity ratio, r₁ = 5.6, was obtained from the copolymer composition at complete consumption of M₁, assuming that the rate constant k₂₂ =0,i.e. r₂ =0. The polymers exhibited T_g values of 128 and 119°C, respectively, which correspond to an estimated T_g = 217°C for the hypothetical homopolymer of M₂.     

Thermal analyses of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)

Thermal analyses of poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(HB–HV)], and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB–HHx)] were made with thermogravimetry and differential scanning calorimetry (DSC). In the thermal degradation of PHB, the onset of weight loss occurred at the temperature (°C) given by T_o = 0.75B + 311, where B represents the heating rate (°C/min). The temperature at which the weight-loss rate was at a maximum was T_p = 0.91B + 320, and the temperature at which degradation was completed was T_f = 1.00B + 325. In the thermal degradation of P(HB–HV) (70:30), T_o = 0.96B + 308, T_p = 0.99B + 320, and T_f = 1.09B + 325. In the thermal degradation of P(HB–HHx) (85:15), T_o = 1.11B + 305, T_p = 1.10B + 319, and T_f = 1.16B + 325. The derivative thermogravimetry curves of PHB, P(HB–HV), and P(HB–HHx) confirmed only one weight-loss step change. The incorporation of 30 mol % 3-hydroxyvalerate (HV) and 15 mol % 3-hydroxyhexanoate (HHx) components into the polyester increased the various thermal temperatures T_o, T_p, and T_f relative to those of PHB by 3–12°C (measured at B = 40°C/min). DSC measurements showed that the incorporation of HV and HHx decreased the melting temperature relative to that of PHB by 70°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 90–98, 2001     

Nitroxide‐mediated synthesis of styrenic‐based segmented and tapered block copolymers using poly(lactide)‐functionalized TEMPO macromediators

Poly(styrene)‐poly(lactide) (PS‐PLA), poly (tert‐butyl styrene)‐poly(lactide) (PtBuS‐PLA) diblocks, and poly(tert‐butyl styrene)‐poly(styrene)‐poly(lactide) (PtBuS‐PS‐PLA) segmented and tapered triblocks of controlled segment lengths were synthesized using nitroxide‐mediated controlled radical polymerization. Well‐defined PLA‐functionalized macromediators derived from hydroxyl terminated TEMPO (PLA_T) of various molecular weights mediated polymerizations of the styrenic monomers in bulk and in dimethylformamide (DMF) solution at 120–130°C. PS‐PLA and PtBuS‐PLA diblocks were characterized by narrow molecular weight distributions (polydispersity index (M_w/M_n) < 1.3) when using the PLA_T mediator with the lowest number average molecular weight M_n= 6.1 kg/mol while broader molecular weight distributions were exhibited (M_w/M_n = 1.47‐1.65) when using higher molecular weight mediators (M_n = 7.4 kg/mol and 11.3 kg/mol). Segmented PtBuS‐PS‐PLA triblocks were initiated cleanly from PtBuS‐PLA diblocks although polymerizations were very rapid with PS segments ～ 5–10 kg/mol added within 3–10 min of polymerization at 130°C in 50 wt % DMF solution. Tapering from the PtBuS to the PS segment in semibatch mode at a lower temperature of 120°C and in 50 wt % DMF solution was effective in incorporating a short random segment of PtBuS‐ran‐PS while maintaining a relatively narrow monomodal molecular weight distribution (M_w/M_n ≈ 1.5). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

ASYMPTOTIC INFERENCES FOR AN AR(1) MODEL WITH A CHANGE POINT: STATIONARY AND NEARLY NON‐STATIONARY CASES

This article examines the asymptotic inference for AR(1) models with a possible structural break in the AR parameter β near the unity at an unknown time k₀. Consider the model y_t = β₁y_{t − 1}I{t ≤ k₀} + β₂y_{t − 1}I{t > k₀} + ϵ_t, t = 1,2, … ,T, where I{ ⋅ } denotes the indicator function. We examine two cases: case I | β₁ | < 1,β₂ = β_2T = 1 − c ∕ T; and case II β₁ = β_1T = 1 − c ∕ T, | β₂ | < 1, where c is a fixed constant, and {ϵ_t,t ≥ 1} is a sequence of i.i.d. random variables, which are in the domain of attraction of the normal law with zero means and possibly infinite variances. We derive the limiting distributions of the least squares estimators of β₁ and β₂ and that of the break‐point estimator for shrinking break for the aforementioned cases. Monte Carlo simulations are conducted to demonstrate the finite‐sample properties of the estimators. Our theoretical results are supported by Monte Carlo simulations.     

Crystal morphology and structure of the β‐form of isotactic polypropylene under supercooled extrusion

A supercooled melt of isotactic polypropylene (iPP) was extruded through a capillary die. Polarized light microscopy (PLM), wide‐angle X‐ray diffraction (WAXD), and differential scanning calorimetry (DSC) were used to investigate the effects of the relatively weak wall shear stress (σ_w), extrusion temperature (T_e), and crystallization temperature (T_c) on the structure and morphology of β‐form isotactic polypropylene (β‐iPP). β‐cylindrites crystals could be observed by PLM in the extruded specimen even at a lower σ_w's (0.020 MPa), and the β‐iPP content increased with decreasing T_e. Under a given T_e of 150°C, the increase in σ_w positively influenced the β‐iPP content. The DSC and WAXD results indicate that the total crystallinity and β‐iPP content increased when T_c was set from 105 to 125°C; the other experimental parameters were kept on the same level. Although T_c was above 125°C, the β‐iPP content obviously decreased, and the total crystallinity continued to increase. On the basis of the influences of σ_w, T_e, and T_c on the β‐iPP crystal morphology and structure, a modified model is proposed to explain the growing of shear‐induced β‐iPP nucleation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Structural development of poly(ethylene terephthalate) during uniaxial stretching above the glass‐transition temperature: Study of the statistical influence of the stretching variables

In this article, we present an investigation of the structural development of poly(ethylene terephthalate) (PET) during uniaxial stretching above the glass‐transition temperature; this followed a statistical design of experiment approach to determine the influence of the stretching variables on the structural development. Amorphous PET was submitted to a stretching program with variations in the stretching temperature (T_st), stretching rate ( $\dot {\varepsilon}_{st}$ ), and stretching ratio (λ_st). Stretched samples were rapidly quenched and characterized by wide‐angle X‐ray scattering, optical birefringence, and differential scanning calorimetry. The relevance and influence of the stretching variables on the obtained parameters (phase fraction, phase orientation, and thermal parameters) were analyzed. The strain‐induced crystallinity was controlled by T_st, λ_st, and the interactions between them. Mesophase development was not dependant on T_st but on the interactions between $\dot {\varepsilon}_{st}$ and λ_st. The molecular orientation was proportionally dependent on T_st, λ_st, and their interactions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrophoretic deposition of titanium nitride coatings

Electrophoretic deposition of the titanium nitride (TiN) coatings from suspensions prepared by dispersion of TiN particles in triethanolamine (TEA) containing butanol medium was studied. Effects of the TiN particles concentration (C_TiN) on the weight of the deposited coatings, triethanolamine concentration (C_TEA=0.25, 0.5, 0.75, and 1 mL/L) on the Zeta potential of the TiN particles, suspension electrical conductivity and pH, as well as effects of the deposition voltage (V_d=60, 90, and 120 V) and time (t_d =1, 2, and 3 minutes) on the microstructure and thickness of the deposited coatings were investigated. Variations in deposition current density, effective deposition voltage, electrical resistance, and deposited coating weight versus deposition time were recorded. The morphology of the as‐dried coatings was studied using Scanning Electron Microscope (SEM). The results indicated that by increasing the C_TiN the weight of deposits increases linearly up to 40 g/L. For suspensions containing C_TiN=40 g/L, the optimum C_TEA is obtained to be 0.5 mL/L leading to Zeta potential of 43.25 mV. Uniform and crack‐free as‐dried coatings obtained at V_d and t_d of 90 V and 2 minutes, respectively.     

Polymer welding relations investigated by a lap shear joint method

A lap shear joint method was used to study strength development during welding of polystyrene surfaces- The surfaces previously had not been in contact and care was taken to insure rapid wetting of the interface. The shear stress at failure, τ_f was measured at room temperature as a function of contact time, t, at constant welding temperatures up no 20°C above the glass transition temperature, T_g. The time dependence of welding could be well described by τ_fαt^1/4. This result is in agreement with predictions of the reptation molecular dynamics model applied to inter-diffusion at a symmetric amorphous polymer-polymer interface. The activation energy for the thermally activated increase in strength development was determined as E = 96 kcal/mol at T = 113.5°C, which compares with E = 93,2 kcal/mole as predicted by the W-L-F theory using C₁ = 13.7, C₂ = 50 and T_g = 100°C. The polystyrene samples had molecular weights, M_n = 143,000 and M_w = 262.000. The time to achieve complete healing, t_∞ ≈? 256 min at 118°C, was found to be of the same order of magnitude as the viscoelastic relaxation time and also with the time required for a polymer chain to diffuse a distance equal to its root mean square end-to-end vector.     

Versatility of a succinimidyl‐ester functional alkoxyamine for controlling acrylonitrile copolymerizations

Styrene/acrylonitrile (S/AN) and tert‐butyl methacrylate/acrylonitrile (tBMA/AN) copolymers were synthesized in a controlled manner (low polydispersity $ {{\overline M _w } / {\overline M _n }} $ with linear growth of number average molecular weight $ \overline M _n $ vs. conversion X) by nitroxide mediated polymerization (NMP) with a succinimidyl ester (NHS) terminated form of BlocBuilder unimolecular initiator (NHS‐BlocBuilder) in dioxane solution. No additional free nitroxide (SG1) was required to control the tBMA‐rich copolymerizations with NHS‐BlocBuilder, a feature previously required for methacrylate polymerizations with BlocBuilder initiators. Copolymers from S/AN mixtures (AN molar initial fractions f_AN,0 = 0.13–0.86, T = 115°C) had $ {{\overline M _w } / {\overline M _n }} $ = 1.14–1.26 and linear $ \overline M _n $ versus conversion X up to X ≈ 0.6. tBMA/AN copolymers (f_AN,0 = 0.10–0.81, T = 90°C) possessed slightly broader molecular weight distributions ( $ {{\overline M _w } / {\overline M _n }} $ = 1.23–1.50), particularly as the initial composition became richer in tBMA, but still exhibited linear plots of $ \overline M _n $ versus conversion X up to X ≈ 0.6. A S/AN/tBMA terpolymerization (f_AN,0 = 0.50, f_S,0 = 0.40) was also conducted at 90°C and revealed excellent control with $ \overline M _n $ = 13.6 kg/mol, $ {{\overline M _w } / {\overline M _n }} $ = 1.19, and linear $ \overline M _n $ versus conversion X up to X = 0.54. Incorporation of AN and tBMA in the final copolymer (molar composition F_AN = 0.47, F_tBMA = 0.11) was similar to the initial composition and represents initial designs to make tailored, acid functional AN copolymers by NMP for barrier materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013