Synthesis and crystallization behavior study of syndiotactic polystyrene‐g‐isotactic polypropylene (sPS‐g‐iPP) graft copolymers

Based on coordination polymerization mechanism only, novel stereoregular graft copolymers with syndiotactic polystyrene main chain and isotactic polypropylene side chain (sPS‐g‐iPP) were synthesized via two steps of catalytic reactions. First, a chain transfer reaction was initiated by a chain transfer complex composed of a styrene derivative, 1,2‐bis(4‐vinylphenyl)ethane, and hydrogen in propylene polymerization mediated by rac‐Me₂Si[2‐Me‐4‐Ph(Ind)]₂ZrCl₂ and MAO, which gave iPP macromonomer bearing a terminal styryl group (iPP‐t‐St). Then the iPP‐t‐St macromonomers of varied molecular mass were engaged in syndiospecific styrene polymerization over a typical mono‐titanocene catalyst (CpTiCl₃/MAO) under different conditions to produce sPS‐g‐iPP graft copolymers of varied structure. With an effective purification process, well‐defined sPS‐g‐iPP copolymers were obtained, which were then subjected to differential scanning calorimetry (DSC) and polarized optical micrograph (POM) studies. The graft copolymers were generally found with dual melting and crystallization temperatures, which were ascribable respectively to the sPS backbone and iPP graft. However, it was revealed that the two segments displayed largely different melting and crystallization behaviors than sPS homopolymer and the precursory iPP‐t‐St macromonomer. Consequently, the graft copolymer exhibited much distinctive crystalline morphologies when compared with their individual components. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Emulsion polymerization of styrene using polystyrene‐block‐poly(ethylene oxide) macromonomers as stabilizers

New diblock macromonomers were used as reactive emulsifiers in the emulsion polymerization of styrene. The nature of the reactive group, the molecular weight, the length of the poly(ethylene oxide) (PEO) block, and the molecular structure of the macromonomer were systematically investigated during this process by analyzing the evolution of the conversion and particle diameters. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2819–2827, 2002     

Controlling grafting density and side chain length in poly(n‐butyl acrylate) by ATRP copolymerization of macromonomers

Atom transfer radical polymerization (ATRP) was used for the preparation and subsequent copolymerization of two acryloyl‐terminated poly(n‐butyl acrylate) macromonomers with different degrees of polymerization (DP_nBA = 25 and 42). Homopolymerization of the higher molecular weight macromonomer ( MM1 ; PnBA₄₂‐A, M_n = 5600, DP_MM = 42, M_w/M_n = 1.18) resulted in preparation of a densely grafted polymer with a narrow molecular weight distribution (M_w/M_n = 1.14), but with the limited degree of polymerization DP = 12. The ultimate degree of homopolymerization for the lower molecular weight macromonomer ( MM2 ; PnBA₂₅‐A, M_n = 3400, DP_MM = 25, M_w/M_n = 1.20) was higher, and DP increased from 12 to 22. The limited DP could be because of progressively increasing steric congestion for macromonomers in approaching the growing chain ends of densely grafted polymers. When MMs were copolymerized with nBA, the reactivity of MM was nearly the same as that of nBA monomer irrespective of the differences in the degree of polymerization of the MMs and the initial molar ratio of nBA to MM. Well‐defined graft polymers with different lengths of backbone and side chains, and different graft density were successfully prepared by “grafting through” ATRP. Tadpole‐shaped and dumbbell‐shaped graft polymers were also synthesized by ATRP. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5454–5467, 2006     

Synthesis of poly(p‐phenylene) macromonomers and multiblock copolymers

Rigid‐rod poly(4′‐methyl‐2,5‐benzophenone) macromonomers were synthesized by Ni(0) catalytic coupling of 2,5‐dichloro‐4′‐methylbenzophenone and end‐capping agent 4‐chloro‐4′‐fluorobenzophenone. The macromonomers produced were labile to nucleophilic aromatic substitution. The molecular weight of poly(4′‐methyl‐2,5‐benzophenone) was controlled by varying the amount of the end‐capping agent in the reaction mixture. Glass‐transition temperatures of the macromonomers increased with increasing molecular weight and ranged from 117 to 213 °C. Substitution of the macromonomer end groups was determined to be nearly quantitative by ¹H NMR and gel permeation chromatography. The polymerization of a poly(4′‐methyl‐2,5‐benzophenone) macromonomer [number‐average molecular weight (M_n) = 1.90 × 10³ g/mol; polydispersity (M_w)/M_n = 2.04] with hydroxy end‐capped bisphenol A polyaryletherketone (M_n = 4.50 × 10³ g/mol; M_w/M_n = 1.92) afforded an alternating multiblock copolymer (M_n = 1.95 × 10⁴ g/mol; M_w/M_n = 6.02) that formed flexible, transparent films that could be creased without cracking. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3505–3512, 2001     

Synthesis of arborescent polystyrene‐g‐[poly(2‐vinylpyridine)‐b‐polystyrene] core–shell–corona copolymers

Arborescent copolymers with a core‐shell‐corona (CSC) architecture, incorporating a polystyrene (PS) core, an inner shell of poly(2‐vinylpyridine), P2VP, and a corona of PS chains, were obtained by anionic polymerization and grafting. Living PS‐b‐P2VP‐Li block copolymers serving as side chains were obtained by capping polystyryllithium with 1,1‐diphenylethylene before adding 2‐vinylpyridine. A linear or arborescent (generation G0 – G3) PS substrate, randomly functionalized with acetyl or chloromethyl coupling sites, was then added to the PS‐b‐P2VP‐Li solution for the grafting reaction. The grafting yield and the coupling efficiency observed in the synthesis of the arborescent PS‐g‐(P2VP‐b‐PS) copolymers were much lower than for analogous coupling reactions previously used to synthesize arborescent PS homopolymers and PS‐g‐P2VP copolymers from the same types of coupling sites. It was determined from static and dynamic light scattering analysis that PS‐b‐P2VP formed aggregates in THF, the solvent used for the synthesis. This presumably hindered coupling of the macroanions with the substrate, and explains the low grafting yield and coupling efficiency observed in these reactions. Purification of the crude products was also problematic due to the amphipolar character of the CSC copolymers and the block copolymer contaminant. A new fractionation method by cloud‐point centrifugation was developed to purify copolymers of generations G1 and above. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1075–1085     

Graft copolymers from star‐shaped and hyperbranched polystyrene macromonomers

Branched polystyrene macromonomers were synthesized by the slow addition of a stoichiometric amount of either 4‐(chlorodimethylsilyl)styrene or vinylbenzyl chloride as a coupling agent to living polystyryllithium. Star‐shaped macromonomers were produced by the addition of the coupling agent alone, and hyperbranched macromonomers resulted from the addition of the coupling agent along with styrene monomer. Star and hyperbranched graft copolymers were produced by the copolymerization of the macromonomers with styrene and methyl methacrylate. The copolymers were characterized by gel permeation chromatography coupled with multi‐angle laser light scattering, ¹H NMR spectroscopy, and Soxhlet extraction to determine that the macromonomers were incorporated in high yields into the copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3547–3555, 2001     

New polyphenylene‐g‐polystyrene and polyphenylene‐g‐polystyrene/poly(ε‐caprolactone) copolymers by combined controlled polymerization and cross‐coupling processes

1,4‐Dibromo‐2‐(bromomethyl)benzene and 1,3‐dibromo‐5‐(bromomethyl)benzene were used as initiators in the atom transfer radical polymerization of styrene in conjunction with CuBr/2,2′‐bipyridine as a catalyst. The resulting polystyrene (PSt)‐based macromonomers, possessing at one end a 2,5‐dibromophenylene or 3,5‐dibromophenylene moiety, were used in combination with 2,5‐dihexylbenzene‐1,4‐diboronic acid for Suzuki coupling in the presence of Pd(PPh₃)₄ as a catalyst or with the system NiCl₂/2,2′‐bipyridine/triphenylphosphine/Zn for Yamamoto polymerization. Polyphenylenes (PPs) with PSt chains as substitution groups were obtained. The same macromonomers were used in Yamamoto copolycondensation reactions, in combination with a poly(ε‐caprolactone) (PCL) macromonomer, and this resulted in PPs with PSt/PCL side chains. The obtained PPs had good solubility properties in common organic solvents at room temperature similar to those of the starting macromonomers. The new polymers were characterized with ¹H (¹³C) NMR, IR, and gel permeation chromatography. The optical properties of the polymers were monitored with UV and fluorescence spectroscopy. The thermal behaviors of the macromonomers and final PPs were investigated with differential scanning calorimetry and compared. The morphology of PPs containing PSt and PCL blocks was characterized with atomic force microscopy, and a microphase‐separated layered morphology was observed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 879–896, 2005     

A macromonomer approach to the synthesis of poly(1,1‐bis(ethoxycarbonyl)‐2‐vinyl cyclopropane‐graft‐dimethyl siloxane)

Poly(1,1‐bis(ethoxycarbonyl)‐2‐vinyl cyclopropane (ECVP)‐graft‐dimethyl siloxane) copolymers were prepared using a macromonomer approach. Poly(dimethyl siloxane) (PDMS) macromonomers were prepared by living anionic polymerization of cyclosiloxanes followed by sequential chain‐end capping with allyl chloroformate. These macromonomers were then copolymerized with ECVP. MALDI‐ToF mass spectrometry and ¹H NMR spectroscopy were used to show that the macromonomers had approximately 80% of the end groups functionalized with allyl carbonate groups. Gradient polymer elution chromatography showed that high yields of the graft copolymers were obtained, along with only small fractions of the PECVP and PDMS homopolymers. Differential scanning calorimetry showed that the low glass transition temperature (T_g) of the PDMS component could be maintained in the graft copolymers. However, the T_g was a function of polymer composition and the polymers produced had T_gs that ranged from ?50 to ?120 °C. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Controlled synthesis of amphiphilic block copolymers based on poly(isobutylene) macromonomers

The synthesis of a monoacrylate functionalized poly(isobutylene) (PIB) macromonomer (PIBA) has been achieved by a two‐step reaction starting from a commercially available PIB. Firstly, terminal olefins (vinylidene and trisubstituted olefin) of PIB were transformed to a phenolic residue by Friedel‐Crafts alkylation followed by subsequent esterification of the phenol with acryloyl chloride, catalyzed by triethylamine. PIBA structure was confirmed by ¹H‐NMR, ¹³C‐NMR and GPC before utilizing in the RAFT copolymerization with N,N‐dimethylacrylamide (DMA) to obtain statistical copolymers (P[(DMA‐co‐(PIBA)]). Monomer conversions were consistently higher than 85% for both DMA and PIBA as monomer feed composition was varied. Chain extension of poly(N,N‐dimethylacrylamide) with PIBA to synthesize block copolymers (P[(DMA‐b‐(PIBA)]) was also achieved with near quantitative monomer conversions (>97%). Block formation efficiency was not quantitative but purification of block copolymers was possible by selective precipitation. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 634–643     

Fluorinated block copolymers containing poly(vinylidene fluoride) or poly(vinylidene fluoride‐co‐hexafluoropropylene) blocks from perfluoropolyethers: Synthesis and thermal properties

PFPE‐b‐PVDF and PFPE‐b‐poly(VDF‐co‐HFP) block copolymers [where PFPE, PVDF, VDF, and HFP represent perfluoropolyether, poly(vinylidene fluoride), vinylidene fluoride (or 1,1‐difluoroethylene), and hexafluoropropylene] were synthesized by radical (co)telomerizations of VDF (or VDF and HFP) with an iodine‐terminated perfluoropolyether (PFPE‐I). Di‐tert‐butyl peroxide (DTBP) was used and was shown to act as an efficient thermal initiator. The numbers of VDF and VDF/HFP base units in the block copolymers were assessed with ¹⁹F NMR spectroscopy. According to the initial [PFPE‐I]₀/[fluoroalkenes]₀ and [DTBP]₀/[fluoroalkenes]₀ molar ratios, fluorinated block copolymers of various molecular weights (1500–30,300) were obtained. The states and thermal properties of these fluorocopolymers were investigated. The compounds containing PVDF blocks with more than 30 VDF units were crystalline, whereas all those containing poly(VDF‐co‐HFP) blocks exhibited amorphous states, whatever the numbers were of the fluorinated base units. All the samples showed negative glass‐transition temperatures higher than that of the starting PFPE. Interestingly, these PFPE‐b‐PVDF and PFPE‐b‐poly(VDF‐co‐HFP) block copolymers exhibited good thermostability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 160–171, 2003     

Synthesis of amphiphilic block–graft copolymers [poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)‐g‐poly(acrylic acid)] and their aggregation in water

Novel block–graft copolymers [poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)‐g‐poly(tert‐butyl acrylate)] were synthesized by the atom transfer radical polymerization (ATRP) of tert‐butyl acrylate (tBA) with chloromethylated poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) as a macromolecular initiator. The copolymers were composed of triblock SEBS as the backbone and tBA as grafts attached to the polystyrene end blocks. The macromolecular initiator (chloromethylated SEBS) was prepared by successive hydrogenation and chloromethylation of SEBS. The degree of chloromethylation, ranging from 1.6 to 36.5 mol % according to the styrene units in SEBS, was attained with adjustments in the amount of SnCl₄ and the reaction time with a slight effect on the monodispersity of the starting material (SEBS). The ATRP mechanism of the copolymerization was supported by the kinetic data and the linear increase in the molecular weights of the products with conversion. The graft density was controlled with changes in the functionality of the chloromethylated SEBS. The average length of the graft chain, ranging from a few repeat units to about two hundred, was adjusted with changes in the reaction time and alterations in the initiator/catalyst/ligand molar ratio. Incomplete initiation was detected at a low conversion; moreover, for initiators with low functionality, sluggish initiation was overcome with suitable reaction conditions. The block–graft copolymers were hydrolyzed into amphiphilic ones containing poly(acrylic acid) grafts. The aggregation behavior of the amphiphilic copolymers was studied with dynamic light scattering and transmission electron microscopy, and the aggregates showed a variety of morphologies. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1253–1266, 2002     

Synthesis of well‐defined macromonomers and comb copolymers from polymers made by atom transfer radical polymerization

Poly(n‐butyl acrylate) macromonomers with predetermined molecular weights (1300 < number‐average molecular weight < 23,000) and low polydispersity indices (<1.2) were synthesized from bromine‐terminated atom transfer radical polymerization polymers via end‐group substitution with acrylic acid and methacrylic acid. These macromonomers, having a high degree of end‐group functionalization (>90%), were radically homopolymerized to obtain comb polymers. A high macromonomer concentration, combined with a low radical flux, was needed to obtain a high conversion of the macromonomers and a reasonable degree of polymerization. By the traditional radical copolymerization of the hydrophobic macromonomers with the hydrophilic monomer N,N‐dimethylaminoethyl methacrylate (DMAEMA), amphiphilic comb copolymers were obtained. The conversions of the macromonomers and comonomer were almost quantitative under optimized reaction conditions. The molecular weights were high (number‐average molecular weight ≈70,000), and the molecular weight distribution was broad (polydispersity index ≈ 3.5). Kinetic measurements showed simultaneous decreases in the macromonomer and DMAEMA concentrations, indicating a relatively homogeneous composition of the comb copolymers over the whole molecular weight range. This was supported by preparative size exclusion chromatography. The copolymerization of poly(n‐butyl acrylate) macromonomers with other hydrophilic monomers such as acrylic acid or N,N‐dimethylacrylamide gave comb copolymers with multimodal molecular weight distributions in size exclusion chromatography and extremely high apparent molecular weights. Dynamic light scattering showed a heterogeneous composition consisting of small (6–9 nm) and large (23–143 nm) particles, probably micelles or other type of aggregates. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3425–3439, 2003     

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     

Catalytic chain‐transfer synthesis of 1,1,2,2‐tetrahydroperfluoroalkyl methacrylate macromonomers

The successful catalytic chain‐transfer synthesis of 1,1,2,2‐tetrahydroperfluoroalkyl methacrylate macromonomers with [bis(aqua)bis(difluoroboryl)dimethylglyoximato]cobalt(II) as a catalyst is reported. Fluoroalkyl methacrylate macromonomers were synthesized in acetone with 2,2′‐azobisisobutyronitrile as the initiator. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4136–4141, 2006     

Two‐sided comb poly(amic ester)–poly(propylene oxide) graft copolymers as porous polyimide precursors

New step‐growth graft block copolymers were synthesized. These two‐sided comb copolymers consisted of a poly(amic ester) (PAE) backbone and pendant poly(propylene oxide) (PPO) grafts. The copolymers were made via a macromonomer approach, in which the 4,6‐bischlorocarbonyl isophthalic acid bis[poly(propylene oxide)] ester macromonomer was synthesized through the reaction of hydroxyl‐terminated PPO oligomers with pyromellitic dianhydride and oxalyl chloride. This macromonomer was subsequently used in step‐growth polymerization with comonomers 4,6‐bischlorocarbonyl isophthalic acid diethyl ester, 2,5‐bischlorocarbonyl terephthalic acid diethyl ester, and 2,2‐bis[4‐ (4‐aminophenoxy)phenyl] hexafluoropropane, and this yielded PPO‐co‐PAE graft copolymers. Accordingly, we report the synthesis and characterization of the PPO oligomer, the PPO macromonomer, and their corresponding PPO‐co‐PAE graft copolymers. Graft copolymers with PPO concentrations of 3–26 wt % were synthesized. These polymers were thermally cured to produce polyimide/PPO composites. The thermolysis of these polyimide/PPO composites yielded porous polyimide films with porosities ranging of 4–22.5%. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2266–2275, 2005     

Random copolymerization of macromonomers as a versatile strategy to synthesize mixed-graft block copolymers

The random copolymerization of norbornene-functionalized macromonomers was explored as a method of synthesizing mixed-graft block copolymers (mGBCPs). The copolymerization kinetics of a model system of polystyrene (PS) and poly(lactic acid) (PLA) macromonomers was first analyzed, revealing a gradient composition of side chains along the mGBCP backbone. The phase separation behavior of mGBCPs with PS and PLA side chains of various backbone lengths and side chain molar ratios was investigated, and increasing the backbone length was found to stabilize the phase-separated nanostructures. The graft architecture was also demonstrated to improve the processability of the mGBCP, compared to a linear counterpart. Investigations of mGBCPs comprised of polydimethylsiloxane and poly(ethylene oxide) side chains exemplified the diverse self-assembled morphologies, including a Frank-Kasper A15 phase, that can be obtained with mGBCPs synthesized by random copolymerization of macromonomers. Lastly, a ternary mGBCP was synthesized by the copolymerization of three macromonomers.     

Energy transfer in poly(3‐hexylthiophene)‐g‐Polyfluorene graft copolymers

Conjugated graft copolymers consisting of a poly(3‐hexylthiophene) (P3HT) backbone and poly(9,9'‐dioctylfluorene) side chains (PF) with different grafting degrees were synthesized by the CuAAC reaction. The properties of these materials were studied by UV‐Vis and fluorescence spectroscopy. The former technique provides insight in their self‐assembly, while the latter is used to study the energy funneling from the PF side chains to the P3HT backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1252–1258     

Synthesis and characterization of a poly(GMA)‐graft‐poly(Z‐L‐lysine) graft copolymer with a rod‐like structure

This study applied the macromonomers and glycidyl methacrylate (GMA) to synthesize a series of the graft copolymers, poly(GMA)‐graft‐poly(Z‐L ‐lysine), and investigated the conformation of the graft copolymer. The graft copolymers were synthesized with different GMA monomer ratios (28 to 89%) and different degrees of polymerization (DP) (8 to 15) of the poly(Z‐L ‐lysine) side chain to analyze secondary structure relationships. Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and both wide angle and small angle X‐ray scattering spectroscopy (WAXS, SAXS) were used to investigate the relationship between the microstructure and conformation of the graft copolymers and the different monomer ratios and side chain DP. In AFM images, n8‐G89 (the graft copolymer containing 89% GMA units and the macromonomer DP is 8) showed tiny and uniform rod‐like structures, and n14‐G43 (the graft copolymer containing 43% GMA units and the macromonomer DP is 14) showed uniform rod‐like structures. FTIR spectra of the graft copolymers showed that the variations of α‐helix and β‐sheet secondary structures in the graft copolymers relate to the monomer ratios of the graft copolymers. However, the X‐ray scattering patterns indicated that the graft copolymer conformations were mainly dependent on the poly(Z‐L ‐lysine) side chain length, and these results were completely in accordance with the AFM images. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4655–4669, 2009     

Novel synthesis of polyethylene–poly(dimethylsiloxane) copolymers with a metallocene catalyst

Polyethylene–poly(dimethylsiloxane) copolymers were synthesized in solution from an ethylene monomer and an ω‐vinyl poly(dimethylsiloxane) (PDMS) macromonomer at 363 and 383 K with EtInd₂ZrCl₂/methylaluminoxane as a catalyst. The copolymers obtained were characterized with Fourier transform infrared spectroscopy, ¹H and ¹³C NMR, size exclusion chromatography, and differential scanning calorimetry. The rheological properties of the molten polymers were determined under dynamic shear flow tests at small‐amplitude oscillations, whereas the physical arrangement of the phase domains was analyzed with scanning electron microscopy (SEM)/energy dispersive X‐ray (EDX). The analysis of the catalyst activity and the resulting polymers supported the idea of PDMS blocks or chains grafted to polyethylene. The changes in the rheological behavior and the changes in the Fourier transform infrared and NMR spectra were in agreement with this proposal. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2462–2473, 2004