Synthesis of conducting PPy/pTHF copolymers

Living polytetrahydrofuran (pTHF) was terminated with the potassium salt of pyrrole to yield polymers with pyrrole end groups. Copolymerization of THF and pyrrole with short and long pTHF segments was achieved by constant potential electrolysis. Syntheses of the block copolymers were performed using tetrabutylammonium tetrafluoroborate, sodium perchlorate, and sodium p‐toluenesulfonate as the supporting electrolytes. Characterization of the block copolymers were based on scanning electron microscopy, differential scanning calorimetry, thermal gravimetry analysis, cyclic voltammetry, and FTIR studies. No significant effect of the chain length on the properties of the copolymers was observed; however, use of different dopants resulted in different thermal and electrochemical behaviors, surface morphologies, and conductivities. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 713–720, 1999     

Synthesis and characterization of conducting copolymers of poly(vinyl alcohol) with thiophene side‐groups and pyrrole

Graft copolymers of poly(vinyl alcohol) with thiophene side‐groups and pyrrole were synthesized by electrochemical polymerization methods. Poly(vinyl alcohol) with thiophene side‐groups (PVATh) was obtained from the reaction between poly(vinyl alcohol) (PVA) and thiophene‐3‐acetic acid. The syntheses of copolymers of PVATh and pyrrole were achieved electrochemically by using three different supporting electrolytes, p‐toluene sulfonic acid (PTSA), sodium dodecyl sulfate (SDS) and tetrabutylammonium tetrafluoroborate (TBAFB). Characterization of PVATh and graft copolymers was performed by a combination of techniques including cyclic voltammetry, scanning electron microscopy, thermal gravimetry, differential scanning calorimetry, size‐exclusion chromatography, ¹H NMR and FT‐IR. The conductivities were measured by the four‐probe technique. Copyright © 2004 Society of Chemical Industry     

Structure and thermal behavior of nylon‐6/polytetrahydrofuran triblock copolymers obtained via anionic polymerization

The structure, crystallization, and phase behavior of nylon6‐b‐polytetrahydrofuran‐b‐nylon6 triblock copolymers synthesized via activated anionic polymerization have been studied. The composition, molecular weight of polytetrahydrofuran (PTHF) soft block, and type of polymeric activators (PACs) have been varied. Differential Scanning Calorimetry (DSC), Wide‐Angle X‐ray Diffraction (WAXD), Transmission Electron Microscopy (TEM), and Polarized Light Microscopy (PLM) experiments have revealed that in triblock copolymers only the nylon‐6 component crystallizes while PTHF segments are amorphous. The soft blocks do not alter the spherulitic crystalline structure of nylon‐6 and hard blocks crystallize in the α‐modification. The degree of crystallinity decreases with increasing PTHF concentration. The phase behavior has been investigated by Dynamic Mechanical Thermal Analysis (DMTA). Two different glass transition temperatures (T_g) for all samples have been observed. This indicates that nylon‐6 and PTHF segments are not molecularly miscible and the copolymers are microphase separated. The mechanical properties of the copolymers synthesized have been evaluated. Nylon‐6 copolymers with soft block concentrations up to 10 w/w %, exhibit improved notched impact strength in comparison to the nylon‐6 homopolymer, retaining relatively high hardness and tensile strength. All copolymers possess low water absorption and good thermal stability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1448–1456, 2002; DOI 10.1002/app.10448     

Multi-block copolymer dispersions through polyurethane macroiniferters

Summary Tetraphenylethane-based polyurethane macroiniferter has been used to prepare polyurethane-polymethacrylic acid multi-block copolymers. These block copolymers have been converted into corresponding anionomers by treating them with triethylamine. Dispersions have been prepared by adding water into dimethylformamide solutions of block copolymers and their anionomers. Particle size and viscosity of the dispersions have been determined. The films obtained from the dispersions have been characterized by mechanical and dynamic mechanical analyses. Received: 18 March 1998/Revised version: 13 April 1998/Accepted: 16 April 1998     

离子液体嵌段聚合物的应用研究进展

对聚合离子液体嵌段共聚物在电解质、CO2分离膜、聚偏氟乙烯(PVDF)膜改性剂等方面的最新应用研究进展进行综述。最后讨论了目前离子液体嵌段聚合物在发展中存在的问题,并展望了离子液体嵌段聚合物的发展前景。     

An NMR study on sequence distributions of block copolymers of poly(butylene terephthalate) and poly(tetramethylene glycol)

Summary The analytical methods to characterize the exact chemical composition and sequence distributions of block copolymers of poly(butylene terephthalate) and poly(tetramethylene glycol) (PBT/ PTMG) were reinvestigated by NMR spectroscopy. To obtain accurate information, the choice of the solvents, NMR experimental conditions, ¹H and ¹³C peak assignments and the methods of calculating various sequence parameters were closely examined. For phenol-d₆/tetrachloroethane(TCE) solutions of two copolymers having the hard segment (PBT) contents of 20 and 35wt.%, various sequence parameters were extracted from NMR spectra. In addition to that, we could accurately measure the actual number average molecular weight of PTMG segments within the copolymer by NMR. Measured average molecular weight of PTMG segments was used to calculate theoretical sequence distributions. The experimental and theoretical sequence parameters as well as chemical compositions were compared with each other. Received: 8 September 1998/Revised version: 31 March 1999/Accepted: 2 April 1999     

Block copolymers derived from azobiscyanopentanoic acid. XI. Properties of silicone–PMMA block copolymers prepared via polysiloxane(azobiscyanopentanamide)s

Mechanical, thermal, and surface properties of poly(dimethylsiloxane)–poly(methyl methacrylate) block copolymers (PDMS-b-PMMA) prepared by the use of polysiloxane(azobiscyanopentanamide)s were intensively investigated. The mechanical strength of block copolymers was found to decrease with an increase of siloxane contents. Dynamic mechanical analysis (DMA) of block copolymers having long siloxane chain length (SCL) and high siloxane content revealed the existence of two glass transitions attributable to microphase separation of two segments. Differential scanning calorimetry (DSC) also gave some evidence of microphase separation supporting the DMA results. It was observed that the incorporation of PDMS segments in block copolymers improved thermal stability of PMMA, as confirmed by thermogravimetric analysis. Surface analysis of the block copolymers films cast from several solutions indicated surface accumulation of PDMS segments, as revealed by water contact angle and ESCA measurements.     

Synthesis of Block Copolymers containing Chain‐Controlled Aramid and Fluoroethylene Segments

Summary: Novel block copolymers containing aromatic polyamide (aramid) and fluoroethylene segments were synthesized by a two‐step solution polycondensation. This synthetic method could control the chain‐length of aramid segments and these copolymers could have high structural regularity. The number‐average molecular weight ( ) of one of these polymers is over 2.0 × 10⁴. Incorporating fluoroethylene segments improves the solubility of the resulting polymer compared with conventional aramids.

The synthesis of the fluoroethylene‐aramid block copolymers.     

Rheo-optical Fourier transform near-infrared spectroscopy of polydimethylsiloxane/polycarbonate block copolymers

A series of polydimethylsiloxane (PDMS)/polycarbonate (PC) block copolymers with varying compositions were investigated by simultaneous mechanical and Fourier transform near-infrared (FTNIR) spectroscopic (rheo-optical) measurements to study segmental orientation during elongation-to-break and cyclic elongation–recovery procedures. Depending on the composition and the block lengths of the copolymers, different orientational and recovery phenomena were observed for the hard (PC) and soft (PDMS) segments. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1349–1357, 1998     

Synthesis of conducting polysiloxane — polypyrrole graft copolymers

Summary Polysiloxane-polypyrrole graft copolymers have been synthesized by a series of chemical reactions and subsequent electropolymerization. First, the hydrosilation of 4-vinyl aniline by dimethyl-methylhydrosiloxane copolymer gave the corresponding aminophenyl functional polydimethylsiloxane (PDMS-NH₂). The side chain pyrrole functionalized polysiloxanes were then prepared by the reaction of PDMS-NH₂ with glycidylpyrrole. Finally, the synthesis of graft copolymers of polysiloxane and pyrrole has been achieved electrochemically by using two different electrolytes, p-toluene sulfonic acid (PTSA) and tetrabutylammonium tetrafluoroborate (TBAFB). Characterization of these graft copolymers were performed by a combination of techniques consisting of scanning electron microscopy (SEM), thermal gravimetry (TGA), differential scanning calorimetry (DSC) analyses and FT-IR studies. The conductivities were measured by four-probe technique. Received: 19 September 2001/ Revised version: 4 December 2001/ Accepted: 2 December 2001     

Conduction mechanism in H‐type polysiloxane‐polypyrrole block copolymers

Conducting polymers of polysiloxane‐polypyrrole were synthesized by electropolymerization of the pyrrole monomer through pyrrole moieties in N‐pyrrole‐terminated polysiloxanes. Sodium paratoluene sulfonate was used as the electrolyte. Scanning electron microscopy (SEM) was used to determine the surface morphology of the films. The room‐temperature conductivity values of the films were found to be in the range of 1.9–4.4 × 10^?4 (Ω cm)^?1, depending on the supporting electrolyte concentration. The temperature dependence of the dc conductivities of the copolymers having different dopant concentrations was investigated within the temperature range of 100–320 K. The evaluated parameters showed that the electrical transport is dominated by variable range hopping. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 52–56, 2002     

聚醚酰胺嵌段共聚物的合成及表征

采用熔融缩聚法合成了聚酰胺(PA)6/聚四氢呋喃(PTEMG)嵌段共聚物,研究了PA6、PTEMG链段的相对分子质量、含量对嵌段共聚物热性能的影响,通过傅立叶变换红外光谱、核磁共振、差示扫描量热、热重测试等对产物进行分析.结果表明,嵌段共聚物以羧基封端,当PA6、PTEMG链段相对分子质量分别为2 000、1 000时,共聚物的分子序列长度最长,相对分子质量最大;PTEMG链段相对分子质量越小,共聚物的熔点越低;PTEMG链段相对分子质量相同时,随PA6链段相对分子质量的增加,熔点升高;嵌段共聚物中PA6组分的熔融温度范围随着PTEMG含量的增加而逐步变宽;共聚物具有较高的热分解活化能.     

Some effects of monomer sequence on the viscoelastic behavior of random copolymers of butadiene and styrene

The copolymerization of butadiene and styrene by lithium alkyls can be regulated to give either random or block copolymers. The block copolymers exhibit characteristic mechanical behavior which is attributable to their two-phase domain structure. In random copolymers free of long sequences of styrene there exists, nevertheless, the possibility of varying the sequence distribution by changing the manner in which composition varies along the polymer chain. Since copolymers of butadiene and styrene differing sufficiently in composition are likewise incompatible and will form multi-phase systems, it is likely that microheterogeneity can exist in certain “random” copolymers. Five copolymers of monomer ratio 70 : 30 butadiene/styrene, varying from a uniformly randomized sample, in which composition was very nearly independent of conversion, to a block polymer containing 22% block styrene chemical analysis, were prepared for the present investigation. Composition vs. conversion data indicated that all but the last polymer were free of long styrene sequences, with the composition distribution (along the chain) broadening systematically throughout the remainder of the series. The melt viscosity of the unvulcanized copolymers was distinctly affected by sequence distribution effects. Thus, the temperature coefficient of the apparent viscosity was independent of shear stress only for the uniformly randomized copolymer. In all others temperature superposition of the non-NEWTON ian flow curves was impossible, the discrepancies becoming larger the broader the composition distribution. The results can be explained qualitatively by association effects attributable to a domain structure similar to that found in block polymers. When these copolymers were cross-linked with dicumyl peroxide at 153 °C and the dynamic properties of the networks examined, no clear evidence of a domain structure was found except in the block polymer. Only the latter exhibited more than a single loss maximum. Temperature-frequency reduction of the dynamic measurements was successful with all but the block polymer. Whereas the parameters C₁ and C₂ in the WILLIAMS -LANDEL -FERRY equation appear to change systematically with the degree of randomness, there is evidence that this is attributable to a slight systematic drift toward higher vinyl unsaturation with increasing randomization of the monomer sequence. Relaxation spectra calculated for 25 °C were very nearly the same for all four random copolymers. When the polymers were cross-linked by gamma radiation at room temperature, the resulting networks did show properties indicative of a domain structure in the compositionally more heterogeneous copolymers. It is proposed that compatibility of chain segments of varying composition at the temperature of cross-linking leads to a suppression of the domain structure in the peroxide-cured rubbers, as segments of different composition are joined together. Independent evidence from stress-optical measurements supports this interpretation. The present investigation permits the conclusion that differences in sequence distribution of butadiene-styrene copolymers have, at best, only very minor effects on the visco-elastic properties of conventional vulcanizates, provided the polymers contain no long sequences of styrene units, i.e., polystyrene blocks detectable by classical methods. This is not true of the low shear melt viscosity, which senses relatively small differences in the composition and/or sequence distributions of the uncured rubbers.     

Preparation and identification of a soluble copolymer from pyrrole and o-toluidine

A series of copolymers were prepared by chemically oxidative polymerization of pyrrole (PY) and ortho-toluidine (OT) in HCl aqueous medium. The yield, intrinsic viscosity, and solubility of the copolymers were studied by changing the monomer molar ratio. The resulting PY/OT copolymers were identified by FTIR, ¹H–NMR, DSC, and WAXD techniques. The experimental results showed that the oxidative polymerization of pyrrole and o-toluidine is exothermic and the resulting polymers exhibit an enhanced solubility in most organic solvents compared with that of pyrrole homopolymer. The polymer obtained is a real and amorphous copolymer containing pyrrole and o-toluidine units. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 510–518, 2001     

LC multiblock copolymers containing polysulfone segments. II. Material properties

The synthesis of multiblock copolymers containing liquid crystalline, semi-aromatic polyester segments of poly(ethylene terephthalate-co-oxybenzoate), and polysulfone segments with different segment molecular weights was recently described. Such block copolymers should make it possible to combine properties of the base homopolymers, e.g., the high strength of liquid crystalline polymers (LCP) with the high thermostability of polysulfone (PSU). Investigations of melt rheology and relaxation behavior discussed here demonstrated that the properties of the block copolymers are intermediate between those of the homopolymers and can be tailored by using PSU and LCP segments of suitable molecular weight. The high melt viscosity of PSU is lowered by block copolymer formation, allowing good processability by injection molding. The material properties of the resulting samples are characterized by a combination of PSU thermostability and improved strength. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 619–630, 1997     

Properties of random and block copolymers of butadiene and styrene. I. Dynamic properties and glassy transition temperatures

The effect of monomer sequence on physical properties was investigated for butadienestyrene solution copolymers made by organolithium initiation. The polymers varied from random copolymers of uniform composition along the polymer chain to ideal block polymers of specific block sequence arrangement and included rubbers of intermediate degrees of randomness. Uniform composition random copolymers exhibit a single glass transition temperature and a very narrow dynamic loss peak corresponding to this transition. The glass transition can be predicted from the styrene content and the microstructure of the butadiene portion of the rubber. Random copolymers in which composition varies along the polymer chain, and to some extent between molecules, exhibit a single glass transition, but the dynamic loss peak is broadened. The extent of this broadening is shown to be compatible with the sequence distribution, polymer segments of various compositions losing mobility at different temperatures. This indicates a tendency for association between segments of different temperatures. This indicates a tendency for association between segments of different chains which are similar in composition. Block copolymers display two transitions, corresponding to T_g for each type of block. The position and width of the dynamic loss peaks are related to block length and compositional purity of the blocks.     

ABA-type block copolymers containing poly(dimethylsiloxane) and ketonic resins

Block copolymer containing segments of poly(dimethylsiloxane) (PDMS) and ketonic resins were synthesized. Dihydroxy-terminated PDMS were reacted with the isophorone diisocyanate (IPDI) to obtain the diisocyanate-terminated PDMSs (urethane). These urethanes were reacted with reactive hydroxyl groups in the cyclohexanone–formaldehyde, acetophenone–formaldehyde, and in situ melamine-modified cyclohexanone–formaldehyde resins. Formation of block copolymers was illustrated by several characterization methods, such as chemical and spectroscopic analysis and gel permeation chromatography. The solubilities of the block copolymers were determined, and their surface properties were investigated by contact angle measurements. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 643–648, 1998     

Copolyester studies. V. Preparation and characterization of tetramethylene terephthalate–poly(tetramethylene oxide) random block copolymers

Random block copolymers of tetramethylene terephthalate and polytetrahydrofuran (PTHF) were prepared by melt polycondensation. Five different molecular weights of PTHF were used in the polymerizations with up to 30% by weight incorporation. The copolymers so obtained were characterized in terms of their molecular weight by means of endgroup analysis and solution viscometry. Compositions were established by nuclear magnetic resonance spectroscopy. Thermal properties were studied by differential scanning calorimetry and dynamic mechanical methods. Melting and glass transition temperatures are discussed in terms of the structural differences, particularly the effect of polyether composition and block size on chain flexibility.     

Synthesis and characterization of N-phenylmaleimide-methylvinylisocyanate copolymers with polystyrene side chains

Summary N-Substitued maleimide-methylvinylisocyanate copolymers with high glass transition temperature (T_g) was prepared and reacted with 4-hydroxy TEMPO (4-hydroxy-2,2,6,6-tetramethyl piperidinoxy) to yield polymers possessing stable radical at the side chain. The resulting polymers behaved as polymeric counter radicals for the radical polymerization of styrene. Thus, stable free radical mediated polymerization at the side chain was achieved. The resulting graft copolymers were characterized by spectral and thermal analysis. Received: 6 October 1999/Revised version: 7 March 2000/Accepted: 7 March 2000     

Electropolymerization and electrochemical properties of (N-hydroxyalkyl)pyrrole/pyrrole copolymers

In this study, the N-hydroxyalkyl derivatives of pyrrole (Py), N-(2-hydroxyethyl)pyrrole (HE) and N-(3-hydroxypropyl)pyrrole (HP), were synthesized. The corresponding homopolymers, PHE and PHP, together with the copolymers of Py/HE and those of Py/HP were prepared by galvanostatic polymerization. These monomers and polymers were characterized by FTIR spectroscopy, elemental analysis, SEM and electrochemical techniques. The result of potential-time profiles showed that a higher potential was required for HE and HP than Py for the polymerization. This was ascribed to the steric hindrance of high concentration of the N-hydroxyalkyl groups. However, a similar potential was observed for the copolymerization of Py/HE and Py/HP systems as that of Py due to the reduction of the steric effect by lower content of the substituent. The SEM micrographs showed a rougher morphology for the films synthesized from the solutions with higher Py/derivatives ratio. The cyclic voltammograms indicated that all the copolymers were larger, while the homopolymers had smaller anodic/cathodic currents and specific charges than PPy. This implied that the existence of the proper amount of the N-hydroxyalkyl pendant groups enhanced the ionic mobility of the pyrrole polymers. The results of charge/discharge measurements showed that the copolymer PYHP82 has the highest discharge capacity among the pyrrole polymers prepared.