Cationic poly(methacryl oxyethyl trimethylammonium) and its poly(ethylene glycol)‐grafted analogue as capillary coating materials in electrophoresis

Cationic polyelectrolytes were synthesized and used as semipermanent coating materials for capillaries in electrophoresis. The polyelectrolytes used were a homopolymer of poly(methacryl oxyethyl trimethylammonium chloride) (PMOTAC) and its poly(ethylene glycol) (PEG)‐grafted analogue. Two PMOTAC polyelectrolytes, with molar masses of 85,000 and 300,000 g/mol, and PEG‐grafted PMOTAC with a molar mass of 280,000 g/mol were synthesized and then characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. Attachment of the polyelectrolytes to the wall of the fused silica capillary for electrophoresis caused the electroosmotic flow (EOF) to reverse. The polyelectrolyte coatings were tested over the pH range 2–11 at different buffer ionic strengths, and the most stable and strongest anodic EOFs were obtained at acidic pH values with low ionic strength buffers. Between runs the capillary is merely rinsed for 2 or 3 min with the background electrolyte solution. With the PMOTAC coatings at pH values ≤5, the RSDs of the EOFs were less than 2.9% after 60 injections. The effects of the molar mass of the polycation and of PEGylation of PMOTAC on the interactions between the polycations and basic proteins were studied at acidic pH values. The differences in the effective electrophoretic mobilities, resolution values, and plate numbers of the proteins with the different coatings were due to the EOF, as demonstrated through calculations of reduced mobilities, relative resolution values, and relative plate numbers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2655–2663, 2007     

Water-soluble hydrogen-bonding interpolymer complex formation between poly(ethylene glycol) and poly(acrylic acid) grafted with poly(2-acrylamido-2-methylpropanesulfonic acid)

Comb-type copolymers of poly(acrylic acid) grafted with poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPSA) side chains form with poly(ethylene glycol), at low pH, water-soluble hydrogen-bonding interpolymer complexes. Turbidimetry, viscometry, and dynamic light scattering measurements suggest that compact, negatively charged, colloidal nanoparticles are formed at pH<3.75. The influence of the structure of the graft copolymers and of the ionic strength of the solution on the size of these nanoparticles was investigated. It was found that their hydrodynamic radius decreases by increasing the molecular mass of the PAMPSA side chains of the graft copolymer and increases with increasing the ionic strength of the solution.     

Radiation grafting of styrene onto poly(vinylidene fluoride) films in propanol: The influence of solvent and synthesis conditions

Electron‐beam‐irradiated poly(vinylidene fluoride) films were grafted with styrene with propanol or toluene as a solvent. The influence of the synthesis conditions and, more particularly, of the solvent was investigated. In propanol, the order of dependence of the grafting rate is 0.43 on the pre‐irradiation dose and 1.2 on the monomer concentration. The activation energy of the grafting reaction in propanol is approximately 73 kJ/mol. Both the initial grafting rate and the saturation degree of grafting are considerably higher in propanol, which is unable to swell polystyrene grafts, than in toluene, which diffuses with styrene through the grafted moiety. The grafting solvent also influences the structure of the membrane: films grafted in propanol have a much reduced elongation at break and a rougher surface. It is suggested that phase‐separated polystyrene domains may be larger when grafting is carried out in a styrene–propanol solution. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1512–1519, 2000     

Reversible structure destruction of intramolecular polycomplexes formed by poly(acrylamide) and poly(vinyl alcohol), under hydrodynamic shear flow

A set of rheologic and thermodynamic researches of diluted and semi‐diluted aqueous solutions of poly(acrylamide) to poly(vinyl alcohol) grafted copolymers (PVA‐PAA_N) forming intramolecular polycomplexes (Intra PC) by the methods of static light scattering, interferometry and rheology (for gradients of shear rate j≤1312 s⁻¹) was carried out. It is established, that the thermodynamic water quality towards the copolymers improves, when the quantity N of grafts increases, but on the whole it remains close to θ‐solvent. In PVA‐PAA_N solutions under action of a hydrodynamic shear field two level of reversible structure destruction are shown. The first level is destruction of network of pinnings and the second one is destruction of Intra PC structure together with destroying of primary associates of copolymer macromolecules. It is shown, that the character of destruction (gradual or uneven) and its depth depend on intensity of the hydrodynamic shear field action, concentration of solution and also copolymer structure. Possible reason of reversibility of PVA‐PAA_N structure destruction in strong hydrodynamic fields is pointed out.     

Graft copolymerization kinetics of acrylic acid onto the poly(ethylene terephthalate) surface by atmospheric pressure plasma inducement

After one atmospheric pressure plasma treatment of poly(ethylene terephthalate) (PET) film, acrylic acid (AAc) in aqueous solution was successfully graft‐copolymerized onto PET films. The effects of reaction time, AAc monomer concentration and reaction temperature on grafting behavior of AAc were systematically studied. Possible reaction kinetics of plasma‐induced graft copolymerization, starting from initial hydroperoxide decomposition, were proposed. Through the Arrhenius analysis about graft copolymerization kinetics of AAc monomers on PET surface, it was revealed that the activation energies of decomposition, propagation and termination were 98.4, 63.5, and 17.5 kJ/mol, respectively. The temperature around 80 °C was favorable not only for the formation of oxide radicals through the thermal decomposition of hydroperoxide on PET surface but also for the extension of graft copolymer chain through direct polymer grafting. Poly(acrylic acid) (PAAc) grains grafted onto PET surfaces possessed relatively uniform size and both PAAc grain size and surface roughness increased with increasing the grafting degree of AAc. The increase of grain size with increasing grafting degree results from the possibility of forming long chain graft copolymers and their shielding of reactive sites. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1594–1601, 2008     

Synthesis and characterization of novel photoactive polymer poly(vinyl alcohol)‐graft‐poly(vinyl naphthalene)

A copolymer of poly(vinyl naphthalene) grafted onto poly(vinyl alcohol) has been synthesized with nitroxide‐mediated controlled radical polymerization. By separating the processes of the generation of grafting sites and polymerization, we can avoid the formation of the homopolymer. Because of its architecture, the polymer is soluble in water, despite the high content of hydrophobic groups. The naphthalene chromophores tend to aggregate, forming hydrophobic microdomains in an aqueous solution. Those aggregates exist in a very constrained environment that leads to extraordinarily large redshifts of both the absorption and emission of the polymer. The polymer acts as an efficient photosensitizer in photoinduced electron transfer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2675–2683, 2006     

Synthesis of multiblock hyperbranched‐linear poly(ether sulfone) copolymers

Hyperbranched poly(ether sulfone) was prepared in the presence of an oligomeric linear poly(ether sulfone) to generate multiblock hyperbranched‐linear (LxHB) copolymers. The LxHB copolymers were prepared in a two‐step, one‐pot synthesis by first polymerizing AB monomer to generate a linear block of a desired molecular weight followed by addition of the AB₂ monomer in a large excess (19:1, AB₂:AB) to generate the hyperbranched block. NMR integration analysis indicates that AB₂:AB ratio is independent of the reaction time. Because the molecular weight still increases with reaction time, these results suggest that polymer growth continues after consumption of monomer by condensation into a multiblock architecture. The LxHB poly(ether sulfone)s have better thermal stability (10% mass loss > 343 vs. 317 °C) and lower T_g (200 vs. > 250 °C) than the hyperbranched homopolymer, higher T_g than the linear homopolymer (<154 °C), while little difference in the solubility character was observed between the two polymers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4785–4793, 2008     

Compatibilizing effect of a graft copolymer on bacterial poly(3‐hydroxybutyrate)/poly(methyl methacrylate) blends

Blends of isotactic (natural) poly(3‐hydroxybutyrate) (PHB) and poly(methyl methacrylate) (PMMA) are partially miscible, and PHB in excess of 20 wt % segregates as a partially crystalline pure phase. Copolymers containing atactic PHB chains grafted onto a PMMA backbone are used to compatibilize phase‐separated PHB/PMMA blends. Two poly(methyl methacrylate‐g‐hydroxybutyrate) [P(MMA‐g‐HB)] copolymers with different grafting densities and the same length of the grafted chain have been investigated. The copolymer with higher grafting density, containing 67 mol % hydroxybutyrate units, has a beneficial effect on the mechanical properties of PHB/PMMA blends with 30–50% PHB content, which show a remarkable increase in ductility. The main effect of copolymer addition is the inhibition of PHB crystallization. No compatibilizing effect on PHB/PMMA blends with PHB contents higher than 50% is observed with various amounts of P(MMA‐g‐HB) copolymer. In these blends, the graft copolymer is not able to prevent PHB crystallization, and the ternary PHB/PMMA/P(MMA‐g‐HB) blends remain crystalline and brittle. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1390–1399, 2002     

Synthesis and hydrolytic stability of poly(oxyethylene‐H‐phosphonate)s

Poly(oxyethylene‐H‐phosphonate)s (POE‐H‐Ps), with different poly(oxyethylene) segment lengths, were synthesized via conventional two‐stage polycondensation reaction of dimethyl‐H‐phosphonate and poly(ethylene glycols) (PEGs), with nominal molecular weights of 400, 600, and 1000 Da. The changes in the composition of the reaction mixtures during the polycondensation process were followed by size‐exclusion chromatography (SEC) and NMR. It was found that the three PEG fragments yield reproducibly POE‐H‐Ps with the following molecular weights: ～3000 Da (PEG‐400), ～6000 Da (PEG‐600), and ～10,000 Da (PEG‐1000) as measured by SEC, NMR, and VPO. The hydrolytic behavior of POE‐H‐Ps upon storage and in aqueous media with pH 3, 7.4, and 8 was studied for the first time by a combination of NMR and SEC. It was found that the long‐term stability of the polymers in dry state depends on the length of the PEG fragments and decreased in the following order: POE‐H‐P_(PEG‐1000) > POE‐H‐P_(PEG‐600) > POE‐H‐P_(PEG‐400). The hydrolytic transformation of the polymers in aqueous media is affected mostly by the pH of the solution. The degradation products are PEG fragments containing phosphonate end groups—an important prerequisite for the usage of the POE‐H‐Ps as nontoxic drug delivery vehicles and in vivo precursors for PEGylated prodrugs. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4130–4139, 2008     

Hydrophilic–hydrophobic AB diblock copolymers containing poly(trimethylene carbonate) and poly(ethylene oxide) blocks

AB‐type block copolymers with poly(trimethylene carbonate) [poly(TMC); A] and poly(ethylene oxide) [PEO; B; number‐average molecular weight (M_n) = 5000] blocks [poly(TMC)‐b‐PEO] were synthesized via the ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of monohydroxy PEO with stannous octoate as a catalyst. M_n of the resulting copolymers increased with increasing TMC content in the feed at a constant molar ratio of the monomer to the catalyst (monomer/catalyst = 125). The thermal properties of the AB diblock copolymers were investigated with differential scanning calorimetry. The melting temperature of the PEO blocks was lower than that of the homopolymer, and the crystallinity of the PEO block decreased as the length of the poly(TMC) blocks increased. The glass‐transition temperature of the poly(TMC) blocks was dependent on the diblock copolymer composition upon first heating. The static contact angle decreased sharply with increasing PEO content in the diblock copolymers. Compared with poly(TMC), poly(TMC)‐b‐PEO had a higher Young's modulus and lower elongation at break. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4819–4827, 2005     

Phosphonyl/hydroxyl hydrogen bonding–induced miscibility of poly(arylene ether phosphine oxide/sulfone) statistical copolymers with poly(hydroxy ether) (phenoxy resin): Synthesis and characterization

High molecular weight bisphenol A or hydroquinone‐based poly(arylene ether phosphine oxide/sulfone) homopolymer or statistical copolymers were synthesized and characterized by thermal analysis, gel permeation chromatography, and intrinsic viscosity. Miscibility studies of blends of these copolymers with a (bisphenol A)‐epichlorohydrin based poly(hydroxy ether), termed phenoxy resin, were conducted by infrared spectroscopy, dynamic mechanical analysis, and differential scanning calorimetry. All of the data are consistent with strong hydrogen bonding between the phosphonyl groups of the copolymers and the pendent hydroxyl groups of the phenoxy resin as the miscibility‐inducing mechanism. Complete miscibility at all blend compositions was achieved with as little as 20 mol % of phosphine oxide units in the bisphenol A poly(arylene ether phosphine oxide/sulfone) copolymer. Single glass transition temperatures (T_g) from about 100 to 200°C were achieved. Replacement of bisphenol A by hydroquinone in the copolymer synthesis did not significantly affect blend miscibilities. Examination of the data within the framework of four existing blend T_g composition equations revealed T_g elevation attributable to phosphonyl/hydroxyl hydrogen bonding interactions. Because of the structural similarities of phenoxy, epoxy, and vinylester resins, the new poly(arylene ether phosphine oxide/sulfone) copolymers should find many applications as impact‐improving and interphase materials in thermoplastics and thermoset composite blend compositions. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1849–1862, 1999     

Syntheses and characterization of block copolymers of poly(aliphatic ester) with clickable polyphosphoester

We report a series of biocompatible and biodegradable block copolymers of poly(ε‐caprolactone) with “clickable” polyphosphoester (PPE). The block copolymers are synthesized through controlled ring‐opening polymerization of five‐membered cyclic phosphoester monomer, propargyl ethylene phosphate (PAEP), initiated with poly(ε‐caprolactone) macroinitiator. The polymerization followed first‐order kinetics with living polymerization characteristics, thus the molecular weight and composition of copolymers are tunable by adjusting the feed ratio of PAEP monomer to macroinitiator. Azide‐functionalized poly(ethylene glycol) has been grafted to the copolymer to demonstrate the reactive feasibility by Cu(I)‐catalyzed “click” chemistry of azides and alkynes, generating “brush‐coil” polymers. The mild conditions associated with the click reaction are shown to be compatible with poly(ε‐caprolactone) and PPE backbones, rendering the click reaction a generally useful method for grafting numerous types of functionality onto the block copolymers. The block copolymers also show good biocompatibility to cells, suggesting their suitability for a range of biomaterial applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and solution properties of well‐defined comb‐on‐comb graft polymers

Well‐defined comb‐on‐comb copolymers of styrene, isoprene, and α‐methyl‐styrene are prepared through cascade “grafting‐onto” methods. The polymer main chain is prepared by nitroxide‐mediated radical polymerization while the branches are prepared by anionic polymerization. The “grafting‐onto” approach employs the coupling chemistry of macromolecular anions, such as polystyryllithium, polyisoprenyllithium, or poly(α‐methylstyryl)lithium, toward either benzyl chloride or epoxy ring on precursor backbones. Thus a series of ABA‐, ABB‐, and ABC‐type comb‐on‐comb copolymers are prepared and characterized by gel permeation chromatography equipped with a multi‐angle laser light scattering detector and a viscometer. Unusual “U‐shaped” dependences of radius of gyration, R_g, on molecular weight are observed for comb‐on‐comb products, which are attributable to delayed elution of the densely grafted copolymers from GPC columns. The result also shows that the comb‐on‐comb copolymers exhibit morphologies from hard sphere to cylindrical rod, depending on the length ratio of the main chain to the branches. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5518–5527, 2008     

Synthesis of poly(vinyl acetate)‐graft‐polystyrene by a combination of cobalt‐mediated radical polymerization and atom transfer radical polymerization

Vinyl acetate and vinyl chloroacetate were copolymerized in the presence of a bis(trifluoro‐2,4‐pentanedionato)cobalt(II) complex and 2,2′‐azobis(4‐methoxy‐2,4‐dimethylvaleronitrile) at 30 °C, forming a cobalt‐capped poly(vinyl acetate‐co‐vinyl chloroacetate). The addition of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy after a certain degree of copolymerization was reached afforded 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐terminated poly(vinyl acetate‐co‐vinyl chloroacetate) (PVOAc–MI; number‐average molecular weight = 31,000, weight‐average molecular weight/number‐average molecular weight = 1.24). A ¹H NMR study of the resulting PVOAc–MI revealed quantitative terminal 2,2,6,6‐tetramethyl‐1‐piperidinyloxy functionality and the presence of 5.5 mol % vinyl chloroacetate in the copolymer. The atom transfer radical polymerization (ATRP) of styrene (St) was studied with ethyl chloroacetate as a model initiator and five different Cu‐based catalysts. Catalysts with bis(2‐pyridylmethyl)octadecylamine (BPMODA) or tris(2‐pyridylmethyl)amine (TPMA) ligands provided the highest initiation efficiency and best control over the polymerization of St. The grafting‐from ATRP of St from PVOAc–MI catalyzed by copper complexes with BPMODA or TPMA ligands provided poly(vinyl acetate)‐graft‐polystyrene copolymers with relatively high polydispersity (>1.5) because of intermolecular coupling between growing polystyrene (PSt) grafts. After the hydrolysis of the graft copolymers, the cleaved PSt side chains had a monomodal molecular weight distribution with some tailing toward the lower number‐average molecular weight region because of termination. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 447–459, 2007     

About the compatibility of polymer components in polymer complexes based on poly(acrylamide) and poly(vinyl alcohol)

The issue of applying the usual concepts of polymer compatibility to nonstoichiometric PVA/PAA mixtures of chemically complementary poly(vinyl alcohol) and poly(acrylamide), which form in water solution InterPC (intermolecular polymer complex) stabilyzed by H‐bonds, and PAA to PVA graft copolymers (PVA‐PAA_N) with different grafted chains number N, that are IntraPC (intramolecular polymer complexes) is discussed. PVA and PAA are compatible on molecular level. At the same time PVA/PAA mixture (50/50 W/W) is characterized by heterogeneous structure consists of InterPC with ϕ_char=9g_PVA/g_PAA and the excess of unconnected PAA. In the case of IntraPC, yet, only PVA‐PAA_N, where N=25, is characterized by a single glass transition temperature (Tg). At larger values of N separate PAA domains form giving rise to the corresponding Tg. These results are discussed in view of IntraPC structure peculiarities as a function of N investigated by IR spectroscopy.     

Novel temperature‐ and pH‐responsive graft copolymers composed of poly(L‐glutamic acid) and poly(N‐isopropylacrylamide)

A series of novel temperature‐ and pH‐responsive graft copolymers, poly(L ‐glutamic acid)‐g‐poly(N‐isopropylacrylamide), were synthesized by coupling amino‐semitelechelic poly(N‐isopropylacrylamide) with N‐hydroxysuccinimide‐activated poly(L ‐glutamic acid). The graft copolymers and their precursors were characterized, by ESI‐FTICR Mass Spectrum, intrinsic viscosity measurements and proton nuclear magnetic resonance (¹H NMR). The phase‐transition and aggregation behaviors of the graft copolymers in aqueous solutions were investigated by the turbidity measurements and dynamic laser scattering. The solution behavior of the copolymers showed dependence on both temperature and pH. The cloud point (CP) of the copolymer solution at pH 5.0–7.4 was slightly higher than that of the solution of the PNIPAM homopolymer because of the hydrophilic nature of the poly(glutamic acid) (PGA) backbone. The CP markedly decreased when the pH was lowered from 5 to 4.2, caused by the decrease in hydrophilicity of the PGA backbone. At a temperature above the lower critical solution temperature of the PNIPAM chain, the copolymers formed amphiphilic core‐shell aggregates at pH 4.5–7.4 and the particle size was reduced with decreasing pH. In contrast, larger hydrophobic aggregates were formed at pH 4.2. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4140–4150, 2008     

Synthesis of polybutadiene‐graft‐poly(dimethylsiloxane) and polyethylene‐graft‐poly(dimethylsiloxane) copolymers with hydrosilylation reactions

We report preliminary results for the synthesis of polyethylene‐graft‐poly(dimethylsiloxane) copolymers obtained by catalytic hydrogenation of polybutadiene‐graft‐poly(dimethylsiloxane) copolymers (PB‐g‐PDMS). These last copolymers were synthesized by hydrosilylation reactions between commercial polybutadiene and ω‐silane poly(dimethylsiloxane). The reaction was carried in solution catalyzed by cis‐dichloro bis(diethylsufide) platinum(II) salt. The PB‐g‐PDMS copolymers were analyzed by ¹H and ¹³C NMR spectroscopies, and the relative weight percentages of the grafted poly(dimethylsiloxane) macromonomer were determined from the integrated peak areas of the spectra. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2920–2930, 2004     

Arborescent polystyrene‐graft‐poly(tert‐butyl methacrylate) copolymers: Synthesis and enhanced polyelectrolyte effect in solution

A technique is described for the preparation of arborescent graft copolymers containing poly(tert‐butyl methacrylate) (PtBMA) segments. For this purpose, tert‐butyl methacrylate is first polymerized with 1,1‐diphenyl‐2‐methylpentyllithium in tetrahydrofuran. The graft copolymers are obtained by addition of a solution of a bromomethylated polystyrene substrate to the living PtBMA macroanion solution. Copolymers incorporating either short (M_w ≈ 5000) or long (M_w ≈ 30,000) PtBMA side chains were prepared by grafting onto linear, comb‐branched (G0), G1, and G2 bromomethylated arborescent polystyrenes. Branching functionalities ranging from 9 to 4500 and molecular weights ranging from 8.8 × 10⁴ to 6.3 × 10⁷ were obtained for the copolymers, while maintaining a low apparent polydispersity index (M_w/M_n ≈ 1.14–1.25). Arborescent polystyrene‐graft‐poly(methacrylic acid) (PMAA) copolymers were obtained by hydrolysis of the tert‐butyl methacrylate units. Dynamic light scattering measurements showed that the arborescent PMAA copolymers are more expanded than their linear PMAA analogues when neutralized with NaOH. This effect is attributed to the higher charge density in the branched arborescent copolymer structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2335–2346, 2008     

Preparation of poly(ethylene oxide)‐block‐poly(isoprene) by nitroxide‐mediated free radical polymerization from PEO macroinitiators

Amphiphilic poly(ethylene oxide)‐block‐poly(isoprene) (PEO‐b‐PI) diblock copolymers were prepared by nitroxide‐mediated polymerization of isoprene from alkoxyamine‐terminal poly(ethylene oxide) (PEO). PEO monomethyl ether (M_n ≈ 5200 g/mol) was functionalized by esterification with 2‐bromopropionyl bromide with subsequent copper‐mediated replacement of the terminal bromine with 2,2,5‐trimethyl‐4‐phenyl‐3‐azahexane‐3‐nitroxide. The resulting PEO‐alkoxyamine macroinitiator was used to initiate polymerization of isoprene in bulk and in solution at 125 °C to yield PEO‐b‐PI block copolymers with narrow molecular weight distributions (M_w/M_n ≤ 1.1). Polymerizations were first order in isoprene through 35% conversion. Micellar aggregates of PEO‐b‐PI in aqueous solution were crosslinked by treatment with a water‐soluble redox initiating system, and persistent micellar structures were observed in the dry state by AFM. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2977–2984, 2005     

Miscibility and morphologies of poly(arylene ether phenyl phosphine oxide/sulfone) copolymer/vinyl ester resin mixtures and their cured networks

Nonreactive bisphenol A‐based poly(arylene ether triphenyl phosphine oxide/diphenyl sulfone) statistical copolymers and a poly(arylene ether triphenyl phosphine oxide) homopolymer, each having a number‐average molecular weight of about 20 kg/mol, were synthesized and solution‐blended with a commercial dimethacrylate vinyl ester resin. Free‐radical cured systems produced morphologies that were a function of both the amount of phosphonyl groups and the weight percentage of the copolymers. For example, highly hydrogen‐bonded poly(arylene ether phenyl phosphine oxide) homopolymer/vinyl ester resin mixtures were homogeneous in all proportions both before and after the formation of networks. Copolymers containing low amounts (≤30 mol %) of the phosphonyl groups displayed phase separation either before or during cure. The phase‐separated cured materials generally had phase‐inverted morphologies, such as a continuous thermoplastic copolymer phase and a particulate, discontinuous vinyl ester network phase, except for systems containing a very low copolymer content. The resin modified with a copolymer containing 30 mol % phosphine oxide comonomer showed improved fracture toughness, suggesting the importance of both phase separation and good adhesion between the thermoplastic polymer and the crosslinked vinyl ester filler phase. The results suggested that the copolymers with high amounts of phosphine oxide should be good candidates for interphase sizing materials between a vinyl ester matrix and high‐modulus carbon fibers for advanced composite systems. Copolymers with low amounts of phosphonyl groups can produce tough, vinyl ester‐reinforced plastics. The char yield increases with the concentration of bisphenol A poly(arylene ether phosphine oxide) content, suggesting enhanced fire resistance. The incorporation of thermoplastic copolymers sustains a high glass‐transition temperature but does not significantly affect the thermal degradation onset temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2409–2421, 2000