Synthesis of nonlinear optical polyimides containing azodiamine derivative chromophores and their electrooptic and thermal properties

Some thermally stable second‐order nonlinear optical (NLO) polyimides were synthesized. The polyimides were prepared by the ring‐opening polyaddition of 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride and pyromellitic dianhydride with two aromatic azodiamine derivatives as the NLO chromophores. These chromophores, based on a nitro group connected with azobenzene as the acceptor end of a donor–π‐bridge–acceptor chromophore and a diamine group as the donor end, had specific chemical stability. On the basis of ZERNER'S INDO methods, according to the sum‐over‐states formula, a program for the calculation of nonlinear second‐order optical susceptibilities was devised. The resulting polyimides had high number‐average and weight‐average molecular weights of up to 26,000 and 53,500, respectively, and a large glass‐transition temperature of 248 °C. With an in situ poling and temperature ramping technique, the optimal temperatures (T_opt's) for corona poling were obtained for the largest second‐order NLO response. The electrooptic coefficient (γ₃₃) of a polyimide at a wavelength of 830 nm was up to 21 pm/V after corona poling under its T_opt, and the value remained at elevated temperatures (>90.6% was retained at 240 °C for >120 h). The thermal stability of the NLO polyimides was studied with UV spectrometry after poling of the films. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2478–2486, 2002     

Synthesis and properties of novel Y‐type nonlinear optical polyimides with high thermal stability of second harmonic generation

2,4‐Bis‐(3,4‐dicarboxyphenylcarboxyethoxy)‐1‐(2,2‐dicyanovinyl)benzene dianhydride (4) was prepared and reacted with 4,4′‐oxydianiline, 4,4′‐diaminobenzanilide and 4,4′‐(hexafluoroisopropylidene)dianiline to yield novel Y‐type polyimides 5‐7 containing 2,4‐dioxybenzylidenemalononitrile groups as nonlinear optical (NLO) chromophores, which constitute parts of the polymer backbone. The resulting polyimides 5‐7 are soluble in polar solvents such as dimethylsulfoxide and N,N‐dimethylformamide. Polymers 5‐7 showed a thermal stability up to 330 °C in thermogravimetric analysis thermograms with T_g values obtained from differential scanning calorimetry thermograms in the range 179–194 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films at the 1064 nm fundamental wavelength were around 5.56 × 10^?9 esu. The dipole alignment exhibited exceptionally high thermal stability even at 20 °C higher than the glass‐transition temperature there was no SHG decay below 215 °C because of the partial main‐chain character of polymer structure, which is acceptable for NLO device applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3078–3087, 2008     

Influence of the polymer structure on the achievement of polar orientation in high glass transition temperature nonlinear optical polyimides by photo-assisted poling

We have used combinations of light, heat, and electrostatic fields to investigate the orientation of nonlinear azo-chromophores chemically incorporated into high glass transition temperature (T_g) polyimides. A number of nonlinear optical polyimides have been synthesized in which the interaction between the nonlinear optical chromophore and the polymer main chain was systematically altered to determine to what extent this steric interaction influences the orientation of the nonlinear chromophore. Chromophores in polymers may be oriented by a number of methods: (a) polarized light at room temperature (i.e., photo-induced orientation or PIO), (b) polarized light and electric fields (i.e., photo-assisted poling or PAP) at temperatures ranging from room temperature to the polymer T_g, and (c) electric fields at T_g (thermal poling). While thermal poling and PIO are usually possible, PAP depends strongly on the molecular structure of the polymer. Previously we have shown that PIO can be accomplished at room temperature in a system where the nonlinear chromophore is embedded into the polyimide main chain via the donor substituent, and this orientation can only be thermally erased at temperatures approaching T_g. In this article we show that, whereas photoisomerization can efficiently depole donor-embedded polyimides in a matter of few minutes at room temperature, PAP does not induce any polar order. This behavior is in marked contrast to a structurally related, side-chain, nonlinear polyimide, in which the azo chromophore is tethered via a flexible linkage to the polymer backbone. In this case some PAP occurs even at room temperature, while no PAP is observed for a donor-embedded system with a similar T_g. We suggest that the orientation during PAP below T_g in the side-chain polyimide is primarily due to the movement of the azo side chains, and there is a very little coupling of this motion to the main chain. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1669–1677, 1998     

Synthesis of chromophores and polyimides with a green chemistry approach for second‐order nonlinear optical applications

This article presents the synthesis of nonlinear optical responsive chromophores by adopting a green chemistry approach by coupling N‐methyl‐N‐(2‐hydroxyethyl)‐4‐amino benzaldehyde with barbituric acid, 1,3‐indanedione, and 1,3‐diethyl‐2‐thiobarbituric acid as the acceptors through stilbene linkage. We performed the synthesis in less than 10 minutes at room temperature with water as a solvent without catalyst. Two different side‐chain polyimides were synthesized from poly(hydroxy‐imide)s with chromophores by Mitsunobu reaction. The chromophores were characterized by Fourier transform infrared, ¹H NMR, ¹³C NMR, and elemental analysis. However, the polyimides were characterized by Fourier transform infrared and ¹H NMR. The inherent viscosities (η_inh) of polyimides were determined by Ubbelohde viscometer, which ranged between 0.1793 and 0.1890 dL/g. The molecular weights of the polyimides were determined using gel permeation chromatography and were in range of 23 000 to 26 000. Polyimides demonstrated an excellent solubility in polar aprotic solvents, indicating good processability. Thermal behavior of these polyimides was studied by differential scanning calorimetry and thermogravimetric analysis. The T_g's were in the range of 185°C to 255°C. The change in the molecular orientation in the polymer films after electrical poling was ascertained using ultraviolet‐visible spectrophotometer and atomic force microscopy. The thicknesses and refractive indices of the thin films were determined by an ellipsometer. The second harmonic generation coefficients of the corona‐poled polymer films at T_opt's, determined by the Maker fringe technique, ranged between 59.33 and 77.82 pm/V. High thermal endurance observed for the polyimides is attributed to the extensive hydrogen bonds in the matrix. The developed polyimides showed no decay in second harmonic generation signals below 110°C, indicating the acceptance for nonlinear optical devices.     

Enhancing the glass‐transition temperature of polyimide copolymers containing 2,2′‐bipyridine units by the coordination of nickel malenonitriledithiolate

Polyimide copolymers containing 2,2′‐bipyridine were synthesized and characterized. The glass‐transition temperatures (T_g's) of the polymers ranged from 260 to 300 °C. In contrast to most known organic chromophore‐containing polyimides, the polyimide copolymers in this study showed elevated T_g's (270–320 °C) after coordination with nickel malenonitriledithiolate inorganic chromophores. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 498–503, 2000     

Molecular design,synthesis, and nonlinear optical properties of novel T‐type polyimides with exceptionally high thermal stability of the second harmonic generation

2,5‐Bis‐(3,4‐dicarboxyphenylcarboxyethoxy)‐4′‐nitrostilbene dianhydride was prepared and reacted with 1,4‐phenylenediamine, 4,4′‐oxydianiline, 4,4′‐diaminobenzanilide, and 4,4′‐(hexafluoroisopropylidene)dianiline to yield unprecedented novel T‐type polyimides ( 4 – 7 ) containing 2,5‐dioxynitrostilbenyl groups as nonlinear optical chromophores, which constituted parts of the polymer backbones. 4 – 7 were soluble in polar solvents such as acetone and N,N‐dimethylformamide. They showed thermal stability up to 300 °C in thermogravimetric analysis thermograms; the glass‐transition temperatures obtained from differential scanning calorimetry thermograms were around 153 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films at the 1064‐cm^?1 fundamental wavelength were around 4.35 × 10^?9 esu. The dipole alignment exhibited exceptionally high thermal stability even at 45 °C higher than the glass‐transition temperature, and there was no SHG decay below 200 °C because of the partial main‐chain character of the polymer structure, which was acceptable for nonlinear optical device applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3189–3199, 2004     

Nonlinear optical side‐chain polymers post‐functionalized with high‐β chromophores exhibiting large electro‐optic property

Electro‐optic side‐chain polymers have been synthesized by the post‐functionalization of methacrylate isocyanate polymers with novel phenyl vinylene thiophene vinylene bridge (FTC) nonlinear optical chromophores. For this application, FTC‐based chromophores were modified in their electronic donor structure, exhibiting much larger molecular hyperpolarizabilities compared with the benchmark FTC. Of these new chromophores, absorption spectra, hyper‐Rayleigh scattering experiment, and thermal analysis were carried out to confirm availability as effective nonlinear optical units for electro‐optic side‐chain polymers. The electro‐optic coefficients (r₃₃) of obtained polymers were investigated in the process of in situ poling by monitoring the temperature, current flow, poling field, and electro‐optic signal. Compared with the nonsubstituted analogue, benxyloxy modified FTC chromophore significantly achieved higher nonlinear optical property, exhibiting molecular hyperpolarizability at 1.9 μm of 4600 × 10^?30 esu and an r₃₃ value of 150 pm/V at the wavelength of 1.31 μm. Synthesized electro‐optic polymers showed high glass transition temperature (T_g), so that the temporal stability examination exhibited >78% of the electro‐optic intensity remaining at 85 °C over 500 h. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and characterization of organosoluble polyimides with trifluoromethyl‐substituted benzene in the side chain

New aromatic diamines substituted with a trifluoromethyl group in the side chain, 2,4‐diamino‐3′‐trifluoromethylazobenzene, 2,4‐diamino‐1‐[(4′‐trifluoromethylphenoxy) phenyl] aniline, and 3,5‐diamino‐1‐[(4′‐trifluoromethyl phenoxy) phenyl] benzamide were synthesized and characterized and used to prepare polyimides by a one‐step high‐temperature polycondensation method. Experimental results indicated that the prepared polyimides possess good solubility in strong organic solvents such as N‐methyl‐2‐pyrrolidinone, N,N′‐dimethylformamide, and N,N′‐dimethylacetamide. Homogeneous solutions with solid contents as high as 15–20% can be prepared, which are stable for storing longer than 2 weeks at room temperature. The polyimides exhibited glass‐transition temperatures of 249–292 °C and good thermal stability. The PI‐I_c and PI‐III_c films prepared by casting the fully imidized polymer solutions showed good transparency with cutoff wavelengths at 320–330 nm. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1572–1582, 2002     

Study on side-chain second-order nonlinear optical polyimides based on novel chromophore-containing diamines. I. Synthesis and characterization

Side-chain second-order nonlinear optical polyimides were prepared from four novel chromophore-containing diamines and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride by a traditional two-step process that included a solution polycondensation followed by a chemical imidization. The four diamines were 2,4-di-β-aminoethylamino-6-p-nitrophenylamino-1,3,5-triazine (M1), 4-nitro-4′-[N-(4,6-di-β-aminoethylamino)-1,3,5-triazin-2-yl]amino azobenzene (M2), 2,4-di-p-aminophenylamino-6-p-nitrophenylamino-1,3,5-triazine (M3), and 4-nitro-4′-[N-(4,6- di-4-aminophenylamino)-1,3,5-triazin-2-yl]amino azobenzene (M4). All the polyimides exhibited maximum ultraviolet-visible absorption peaks or shoulders of chromophores at wavelengths below 400 nm, and those based on M1 and M3 were transparent at wavelengths above 450 nm, whereas those based on M2 and M4 were transparent at wavelengths above 550 nm. The polyimides possessed high glass-transition temperatures (T_g's; 218–247 °C) and thermal decomposition temperatures. They were soluble in aprotic solvents such as N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, N,N-dimethyl formamide, and dimethylsulfone. Some were even soluble in common low-boiling-point solvents such as tetrahydrofuran. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4330–4336, 1999     

Synthesis and characterization of spirobifluorene‐based polyimides

The synthesis and properties of organosoluble aromatic polyimides, containing spiro‐skeletal units in the polymer backbone on the basis of the spiro‐diamine monomer, 2,2′‐diamino‐9,9′‐spirobifluorene, are described. In the case of the spiro segment, the two fluorene rings are orthogonally arranged and connected through a tetrahedral bonding carbon atom, the spiro center. As a consequence, the polymer chain is periodically zigzagged with a 90° angle at each spiro center. This structural feature minimizes interchain interactions and restricts the close packing of the polymer chains, resulting in amorphous polyimides that have good solubility in organic solvents. Compared with their fluorene‐based cardo analogues, the spirobifluorene‐based polyimides have an improved solubility. Furthermore, the main‐chain rigidity of the polyimide appears to be preserved because of the presence of the spiro structure, which restricts the free segmental mobility. As a result, these polyimides exhibit a high glass‐transition temperature (T_g's) and good thermal stability. The T_g's of these polyimides were in the range of 287–374 °C, and the decomposition temperatures in nitrogen for a 10% weight loss occurred at temperatures above 570 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3615–3621, 2002     

Hydrolytic stability and high Tg of polyimides derived from the novel 4,9‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]‐diamantane dianhydride

This work reports the synthesis and characterization of diamantane‐based polyimides obtained from 4,9‐bis[4(3,4‐dicarboxyphenoxy)phenyl]diamantane dianhydride and various aromatic diamines. Interestingly, the diamantane‐based polyimides were very stable to hydrolysis. This novel polyimide exhibits a low dielectric constant (2.65–2.77), low moisture absorption (<0.67%), good solubility, high T_g and unusually high thermal stability. Dynamic mechanical analysis (DMA) reveals that the diamantane‐based polyimides have high T_g ranging from 281 to 379 °C. The high‐temperature β₁ subglass transition around 285 °C was observed in polyimide 6a derived from 2,2′‐bis(trifluoromethyl)benzidine. This class of novel diamantane‐based polyimide is very promising for electronic applications, because of its good mechanical properties, good thermal stability, low dielectric constant, excellent hydrolytic resistance, and low moisture absorption. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1673–1684, 2009     

Synthesis and properties of cross‐linkable high molecular weight fluorinated copolyimides

A series of novel high molecular weight fluorinated co‐polyimides (Co‐PIs) containing styryl side chain based on 1,3‐bis(2‐trifluoromethyl‐4‐aminophenoxy)‐5‐(2,3,4,5‐tetrafluorophenoxy)benzene (6FTFPB) were successfully synthesized. The weight‐average molecular weights (M_ws) and polydispersities of the co‐polyimides were in the range 8.93–10.81 × 10⁴ and 1.33–1.82, respectively. The co‐polyimide film showed excellent solubility in organic solvents, high tensile properties (tensile strength exceeded 91 MPa), excellent optical transparency (cutoff wavelength at 332–339 nm and light transparencies above 89% at a wavelength of 550 nm), and high thermal stability (5% thermal weight‐loss temperature up to 510 °C). The casting and spinning films could be cross‐linked by thermal curing. The cured films show better combination property (including excellent resistance to solvents) than that of co‐polyimides. For instance, the glass transition temperature of Co‐PI‐1 (the molar weight ratio of 6FTFPB was 30%) increased from 217 to 271 °C, the tensile strength enhanced from 94 to 96 MPa, the 5% thermal weight‐loss temperature improved from 514 to 525 °C. Moreover, after cured, Co‐PI‐1 film also has a coefficient of thermal expansion (CTE) value of 60.3 ppm °C^?1, low root mean square surface roughness (R_q) at 4.130 nm and low dielectric constant of 2.60. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 349–359     

Soluble alternating copolyimides containing the tetrahydro[5]helicene unit

A series of novel copolyimides have been synthesized from three commercially available dianhydrides and two diamine monomers containing the tetrahydro[5]helicene unit. Some of the copolyimides were soluble in common organic solvents such as 1,1,2,2-tetrachloroethane, N,N-dimethylacetamide, and N-methyl-2-pyrrolidinone. Molecular modeling was used to explain the enhanced solubility of the presented polyimides, based on structural features of the tetrahydro[5]helicene monomeric units. The onset temperatures for 5% weight loss for these polyimides, as assessed by thermogravimetry, were above 430°C in nitrogen. Inherent viscosities of the obtained polyimides were above 0.36 dL/g. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1349–1353, 1998     

Soluble fluorinated polyimides derived from 1,4‐ (4′‐aminophenoxy)‐2‐(3′‐trifluoromethylphenyl)benzene and aromatic dianhydrides

New fluorinated aromatic polyimides were prepared from 1,4‐(4′‐aminophenoxy)‐2‐(3′‐trifluoromethylphenyl)benzene and aromatic dianhydrides via the polycondensation of one‐step high‐temperature and two‐step thermal or chemical imidization methods. Experimental results indicated that some of the polyimides were soluble both in strong dipolar solvents (N‐methyl‐2‐pyrrolidone or N,N‐dimethylacetamide) and in common organic solvents such as tetrahydrofuran, CHCl₃, and acetone. The polyimides showed exceptional thermal and thermooxidative stability and good mechanical properties. No weight loss was detected before a temperature of 520 °C in nitrogen, and the glass‐transition temperatures ranged from 208 to 251 °C. Low dielectric constants (2.55–2.71 at 1 MHz), low refractive indices, and low water absorption were also observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2404–2413, 2001     

Synthesis and properties of polyimides from thianthrene-2,3,7,8-tetracarboxylic dianhydride-5,5,10,10-tetraoxide

Thianthrene - 2,3,7,8 - tetracarboxylic dianhydride - 5,5,10,10 - tetraoxide (TADATO), a dianhydride having two sulfonyls between two phenyl rings, was synthesized and polymerized with several diamines by a two-step method. Tough polyimide membranes were obtained with flexible diamines but not with rigid diamines. Most of TADATO-based polyimides are soluble in polar solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone. IR study confirmed that almost complete imidization of TADATO-based poly(amic acid) membranes could be achieved by thermal treatment at 100, 200, and 300°C for each 1 h. In a series of polyimides based on 4,4′-oxydianiline, the polyimide from TADATO showed higher gas permeability coefficient of CO₂ and higher selectivities of CO₂/N₂ and CO₂/CH₄ than those of polyimides from pyromellitic dianhydride and 3,3′,4,4′-biphenyltetracarboxylic dianhydride, and was comparable to that from 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36 : 485–494, 1998     

Synthesis and characterization of new soluble aromatic polyimides from diaminotetraphenylimidazolinone and aromatic tetracarboxylic dianhydrides

A series of new soluble aromatic polyimides with inherent viscosities of 0.65–1.12 dL/g were synthesized from 1,3-bis(4-aminophenyl)-4,5-diphenylimidazolin-2-one and various aromatic tetracarboxylic dianhydrides by the conventional two-step procedure that included ring-opening polyaddition and subsequent thermal cyclodehydration. These polyimides could also be prepared by the one-pot procedure in homogeneous m-cresol solution. Most of the tetraphenyl-pendant polyimides were soluble in organic solvents such as N,N-dimethylacetamide, 1,3-dimethyl-2-imidazolidone, and m-cresol. Some polyimides gave transparent, flexible, and tough films with good tensile properties. The glass transition temperatures and 10% weight loss temperatures under nitrogen of the polyimides were in the range of 287–326 and 520–580°C, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1767–1772, 1998     

New polyimides incorporated with diphenylpyrenylamine unit as fluorophore and redox‐chromophore

A series of novel polyimides based on N,N‐di(4‐aminophenyl)‐1‐aminopyrene and aromatic or alicyclic tetracarboxylic dianhydrides were synthesized. The polymers exhibited good solubility in many polar organic solvents and could afford robust films via solution casting. The polyimides derived from aromatic dianhydrides exhibited high thermal stability and high glass‐transition temperatures (333–364 °C). Cyclic voltammetry studies of the polymer films showed that these polyimides are both p and n dopable and have multicolored electrochromic states. For the polyimides derived from alicyclic dianhydrides, they revealed a strong blue‐light emission with high fluorescence quantum yields (?_PL > 45%) and a marked solvatochromic behavior. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

High solubility,low‐dielectric constant,and optical transparency of novel polyimides derived from 3,3′,5,5′‐tetramethyl‐4,4′‐diaminodiphenyl‐4″‐isopropyltoluene

A series of novel polyimides (PIs) ( 3a–d ) were prepared from 3,3′,5,5′‐tetramethyl‐4,4′‐diaminodiphenyl‐4 ″ ‐isopropyltoluene ( 1 ) with four aromatic dianhydrides via a one‐step high temperature polycondensation procedure. The obtained PIs showed excellent solubility, with most of them dissoluble at a concentration of 10 wt % in amide polar solvents and chlorinated solvents. Their films were nearly colorless and exhibited high‐optical transparency, with the UV cutoff wavelength in the range of 328–353 nm and the transparency at 450 nm >80%. They also showed low‐dielectric constant (2.49–2.94 at 1 MHz) and low‐water absorptions (0.44–0.65%). Moreover, these PIs possessed high‐glass transition temperatures (T_g) beyond 327 °C and excellent thermal stability with 10% weight loss temperatures in the range of 530–555 °C in nitrogen atmosphere. In comparison with some fluorinated poly(ether imide)s derived from the trifluoromethyl‐substituted bis(ether amine)s, the resultant PIs 3a–d showed better solubility, lower cutoff wavelength, and higher T_g. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3309–3317, 2009     

Nonlinear optical properties of regioregular main‐chain polyesters

We have prepared new polyesters containing quadratic, nonlinear optical (NLO) active chromophores covalently incorporated into the main chain. In these polymers, the sequence of the chromophore units along the main chain is rigorously head to tail. All the polyesters are processable, both in the melt and in solution. For one polyester, a full second‐order NLO characterization has been performed. An out‐of‐resonance d₃₃ coefficient of 21 pm/V at 1368 nm has been measured. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2719–2725, 2007     

Dendronized tricyanopyrroline‐based chromophores in nonlinear optical active host polymer

We synthesized new nonlinear optical (NLO) chromophores containing a 3,5‐bis(3,5‐bisbenzyloxy‐benzyloxy)‐benzoate dendron. Tricyanopyrroline (TCP)‐based chromophores were designed and prepared by virtue of its strong electron withdrawing property. A soluble polyimide containing 6‐({4‐[2‐(1‐allyl‐4‐cyano‐5‐dicyanomethylene‐2‐oxo‐2,5‐dihydro‐1H‐pyrrol‐3‐yl)‐vinyl]‐phenyl}‐butyl‐amino)‐hexanoyl group in the side chain was also prepared as an NLO active host polymer. A benzoate dendron was tethered at two different binding positions of the chromophore to yield two different guest molecules. Thin‐film composites of these dendronized chromophores dissolved in the NLO active polyimide host were employed to fabricate the electro‐optic (EO) samples. The EO properties of new NLO polyimides containing dendronized chromophores were compared with those of the sample with nondendronized plain chromophores. The effect of a bulky dendron on the EO properties was investigated using an in situ reflection technique. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5064–5076, 2008