Synthesis and characterization of poly(ester-sulfone)s

Aliphatic and aromatic-aliphatic poly(ester-sulfone)s were synthesized by the transesterifications of diphenyl adipate and diphenyl phthalates (ortho, meta, para) with two sulfonecontaining diols, 1,3-bis (3-hydroxypropylsulfonyl) propane (Diol-333) and 1,4-bis(3-hydroxypropylsulfonyl) butane (Diol-343). Based on DSC and WAXD studies, the aliphatic homopoly(ester-sulfone)s are semicrystalline at room temperature and liquid crystalline at elevated temperature, while their copolymers with alkanediols are liquid crystalline. The liquid crystalline phase formation in aliphatic poly(ester-sulfone)s is attributed to the strong dipole-dipole interactions between sulfone groups. The aromatic-aliphatic poly(estersulfone)s from diphenyl phthalate (ortho) and isophthalate (meta) are amorphous. They are soluble in trifluoroacetic acid and m-cresol at room temperature, and DMF, DMAC, and DMSO at elevated temperature. The aromatic-aliphatic poly(ester-sulfone)s from diphenyl terephthalate are semicrystalline and are soluble only in trifluoroacetic acid. For a given diol, the glass transition temperatures of aromatic-aliphatic poly(ester-sulfone)s increase from phthalate to isophthalate to terephthalate. This is because the flexibility of the benzene ring in the polymer backbone decreases from ortho to meta to para substitution. As a comparison, polyesters without sulfone groups were synthesized from two alkanediols, 1,9-nonanediol and 1,10-decanediol, and the diphenyl esters. The poly(ester-sulfone)s have glass transition temperatures 60–80°C higher than the corresponding polyesters without sulfone groups, due to the strong dipolar interactions between sulfone groups. © 1994 John Wiley & Sons, Inc.     

Sulfone-Containing polymers as high barrier materials

Three types of sulfone-containing polymers, poly(carbonate-sulfone)s, poly(ester-sulfone)s, and poly(urethane-sulfone)s, were characterized as high barrier materials. They were made by condensing sulfone-containing diol, 1,3-bis(3-hydroxypropylsulfonyl)propane (Diol-333), or 1,4-bis(3-hydroxypropylsulfonyl)butane (Diol-343), with diphenyl carbonate, diphenyl esters, and diisocyanates, respectively. The incorporation of polar sulfone groups into polymer backbones increases the glass transition temperature of polymers in all cases; however, the increment is different with different functional linkages. The increments in polycarbonates and polyesters are higher than that in polyurethanes. This is because the interactions between carbonate or ester groups are much weaker than the interactions between sulfone groups, whereas the hydrogen bonding between urethane groups is comparable with the polar interaction between sulfone groups. The polymers were coated on 50-μm-thick Kapton films by solution casting and their permeabilities toward carbon dioxide were measured at 25°C using the ASTM D1434 volumetric method. The sulfone-containing polymers have carbon dioxide permeability coefficients at least 50 times smaller than the corresponding polymers without sulfone groups. The carbon dioxide barrier properties of sulfone-containing polymers are comparable with ethylene/vinyl alcohol copolymers (EVAL), which are commercial high barrier polymers. An isomer effect on polymer permeability was observed in the aromatic-aliphatic poly(ester-sulfone) series. The permeability coefficients of the aromatic-aliphatic poly(ester-sulfone)s decrease from terephthalate to isophthalate to phthalate, corresponding to the increase of chain flexibility above the T_g. These results support the hypothesis that high chain flexibility in the rubbery state and a glass transition temperature above room temperature are two key factors that promote low permeability. © 1994 John Wiley & Sons, Inc.     

The influence of hard‐segments on two‐phase structure and shape memory properties of PCL‐based segmented polyurethanes

Poly(ε‐caprolactone)‐based segmented polyurethanes (PCLUs) were prepared from poly(ε‐caprolactone) diol, diisocyanates (DI), and 1,4‐butanediol. The DIs used were 4,4′‐diphenylmethane diisocyanate (MDI), 2,4‐toluenediisocyanate (TDI), isophorone diisocyanate (IPDI), and hexamethylene diisocyanate (HDI). Differential scanning calorimetry, small‐angle X‐ray scattering, and dynamic mechanical analysis were employed to characterize the two‐phase structures of all PCLUs. It was found that HDI‐ and MDI‐based PCLUs had higher degree of microphase separation than did IPDI‐ and TDI‐based PCLUs, which was primarily due to the crystallization of HDI‐ and MDI‐based hard‐segments. As a result, the HDI‐based PCLU exhibited the highest recovery force up to 6 MPa and slowest stress relaxation with increasing temperature. Besides, it was found that the partial damage in hard‐segment domains during the sample deformation was responsible for the incomplete shape‐recovery of PCLUs after the first deformation, but the damage did not develop during the subsequent deformation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 557–570, 2007     

Dipole–dipole interaction directed liquid crystalline polymers. I. Aliphatic poly(carbonate-sulfone)s based on 1,3-bis(3-hydroxypropylsulfonyl)propane

Aliphatic poly(carbonate-sulfone) homo- and copolymers were prepared from 1,3-bis(3-hydroxypropylsulfonyl)propane (Diol-333) and various alkanediols. The copolymers are random in nature since they were prepared by melt copolymerization. Both the homopolymer and the copolymers exhibited multiple reproducible first-order transitions during differential scanning calorimetry (DSC) heating scans, but most of them exhibited only single exotherm during cooling scans. Typical schlieren textures were observed when these polymers were cooled from their isotropic melts. The copolymers have wide-angle x-ray diffraction (WAXD) patterns almost identical to that of the homopolymer except in the low-angle spacing, indicating their packing in the crystalline domain in similar. DSC, cross-polarized optical microscopy, and WAXD revealed that these polymers were smectic liquid crystalline at room temperature. Since aliphatic poly(carbonate-sulfone)s are flexible linear polymers with no rigid rod components, the liquid crystalline phase formation is probably directed by the dipole–dipole interactions between sulfone groups in adjacent chains. © 1994 John Wiley & Sons, Inc.     

Synthesis and dielectric analysis of aliphatic poly(carbonate-sulfone)s based on 1,4-bis(3-hydroxypropylsulfonyl) butane

High molecular weight aliphatic poly(carbonate-sulfone) homopolymer (PC-343) and random copolymer (PC-343-10) were synthesized from 1,4-bis(3-hydroxypropylsulfonyl)butane (Diol-343) and a 1/1 molar mixture of Diol-343 and 1,10-decanediol, respectively. As a comparison, an aliphatic polycarbonate homopolymer (PC-10) was prepared from 1,10-decanediol. While PC-10 exhibited a single melting peak during its DSC heating scan, both PC-343 and PC-343-10 exhibited multiple reproducible first-order transitions during DSC heating scans. Both PC-343 and PC-343-10 showed broad reflections in their WAXD diagrams; the crystalline order of PC-343 is higher than that of PC-343-10. Based on the DSC and WAXD results and our discovery on the liquid crystalline behavior of aliphatic poly(carbonate-sulfone)s from 1,3-bis(hydroxypropylsulfonyl)propane, we suggest PC-343 and PC-343-10 are liquid crystalline and the liquid crystalline phase formation is directed by the dipole–dipole interactions between sulfone groups. Films were obtained from these polymers by compression molding and dielectric analyses were conducted on them. One glass transition related dielectric relaxation was observed in PC-343-10. One glass transition related dielectric relaxation and one sub-glass transition related dielectric relaxation were observed in PC-343. The glass transition temperature increases with the increase of sulfone content in the polymers. A dramatic rise in dielectric constant with temperature was observed in PC-343 and PC-343-10 at low frequencies, which is probably due to the sulfone dipole interaction with the electrical field. © 1994 John Wiley & Sons, Inc.     

Sugar‐based hydrophilic polyurethanes and polyureas

Novel linear homogeneous polyurethanes and polyureas with enhanced hydrophilic character have been successfully prepared from sugar‐based monomers having their hydroxyl groups free or partially protected. By the reaction of primary hydroxyl groups of xylitol with dimethyl hexamethylene dicarbamate (HMDC) or di‐tert‐butyl‐4,4′‐diphenyl methyl dicarbamate (MDC), two new linear semicrystalline polyurethanes [PU(X‐HMDC) and PU(X‐MDC)] have been prepared. Likewise, by the reaction of xylitol with the analogous diisocyanates hexamethylene diisocyanate (HMDI) or 4,4′‐methylenebis(phenyl isocyanate) (MDI), similar polyurethanes [PU(X‐HMDI) and PU(X‐MDI)] were obtained. However, these latter polyurethanes present some degree of crosslinking because of the higher reactivity of the diisocyanate comonomers. Linear hydrophilic polyureas having free hydroxyl groups joined to the main chain have also been prepared by the reaction of the same diisocyanates (HMDI and MDI) with 1,6‐diamino‐1,6‐dideoxy‐D ‐mannitol and 1,6‐diamino‐1,6‐dideoxy‐3:4‐O‐isopropylidene‐D ‐mannitol. As far as we are aware, this kind of polyhydroxylated polyurea has not been previously described in the literature. The new polymers were characterized by standard methods (elemental analyses, gel permeation chromatography, IR, and NMR). The polyurethanes were hydrolytically degradable under physiological conditions, in contrast with less‐hydrophilic linear polyurethanes previously described. The thermal properties of the novel polymers were investigated by thermogravimetric analysis and differential scanning calorimetry. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Studies on calcium‐containing poly(urethane ether)s

The calcium salt of mono(hydroxyethoxyethyl)phthalate [Ca(HEEP)₂] was synthesized by the reaction of diethylene glycol, phthalic anhydride, and calcium acetate. Calcium‐containing poly(urethane ether)s (PUEs) were synthesized by the reaction of hexamethylene diisocyanate (HMDI) or tolylene 2,4‐diisocyanate (TDI) with a mixture of Ca(HEEP)₂ and poly(ethylene glycol) (PEG₃₀₀ or PEG₄₀₀) with di‐n‐butyltin dilaurate as a catalyst. A series of calcium‐containing PUEs of different compositions were synthesized with Ca(HEEP)₂/PEG₃₀₀ (or PEG₄₀₀)/diisocyanate (HMDI or TDI) molar ratios of 2:2:4, 3:1:4, and 1:3:4 so that the coating properties of the PUEs could be studied. Blank PUEs without calcium‐containing ionic diols were also prepared by the reaction of PEG₃₀₀ or PEG₄₀₀ with HMDI or TDI. The PUEs were well characterized by Fourier transform infrared, ¹H and ¹³C NMR, solid‐state cross‐polarity/magic‐angle‐spinning ¹³C NMR, viscosity, solubility, and X‐ray diffraction studies. The thermal properties of the polymers were also studied with thermogravimetric analysis and differential scanning calorimetry. The PUEs were applied as top coats on acrylic‐coated leather, and their physicomechanical properties were also studied. The coating properties of PUEs, such as the tensile strength, elongation at break, tear strength, water vapor permeability, flexing endurance, cold crack resistance, abrasion resistance, color fastness, and adhesive strength, were better than the standard values. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2865–2878, 2003     

Preparation and properties of imide‐containing elastic polymers from elastic polyureas and pyromellitic dianhydride

A new approach to obtain imide‐containing elastic polymers (IEPs) via elastic and high‐molecular‐weight polyureas, which were prepared from α‐(4‐aminobenzoyl)‐ω‐[(4‐aminobenzoyl)oxy]‐poly(oxytetramethylene) and the conventional diisocyanates such as tolylene‐2,4‐diisocyanate(2,4‐TDI), tolylene‐2,6‐diisocyanate(2,6‐TDI), and 4,4′‐diphenylmethanediisocyanate (MDI), was investigated. IEP solutions were prepared in high yield by the reaction of the polyureas with pyromellitic dianhydride in N‐methyl‐2‐pyrrolidone (NMP) at 165°C for 3.7–5.2 h. IEPs were obtained by the thermal treatment at 200°C for 4 h in vacuo after NMP was evaporated from the resulting IEP solutions. We assumed a mechanism of the reaction via N‐acylurea from the identification of imide linkage and amid acid group in IEP solutions. NMR and FTIR analyses confirmed that IEPs were segmented polymers composed of imide hard segment and poly(tetramethylene oxide) (PTMO) soft segment. The dynamic mechanical and thermal analyses indicated that the IEPs prepared from 2,6‐TDI and MDI showed a glass‐transition temperature (T_g ) at about −60°C, corresponding to T_g of PTMO segment, and suggested that microphase‐separation between the imide segment and the PTMO segment occured in them. TGA studies indicated the 10% weight‐loss temperatures (T₁₀) under air for IEPs were in the temperature range of 343–374°C. IEPs prepared from 2,6‐TDI and MDI showed excellent tensile properties and good solvent resistance. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 715–723, 2000     

Synthesis and characterization of new poly(amide–imide)s from 1,4-bis(4-trimellitimidophenoxy)-2-tert-butylbenzene with various diamines

New poly(amide–imide)s were prepared from a diimide–dicarboxylic acid, 1,4-bis(4-trimellitimidophenoxy)-2-tert-butylbenzene ( BTTB ), with various diamines by the direct polycondensation in N-methyl-2-pyrrolidinone (NMP) using triphenyl phosphite and pyridine as condensing agents. The new diimide–dicarboxylic acid BTTB containing an ether linkage and tert-butyl substituent was synthesized by the condensation reaction of 1,4-bis(4-aminophenoxy)-2-tert-butylbenzene with trimellitic anhydride. All the polymers were obtained in quantitative yields with inherent viscosities of 0.62–1.06 dL g⁻¹. The polymers were amorphous, and most of them were readily soluble in aprotic polar solvents such as NMP, N,N-dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF), as well as in less polar solvents such as dimethyl sulfoxide (DMSO), m-cresol, pyridine, and γ-butyrolactone, and also even in tetrahydrofuran. The glass transition temperatures of the polymers were determined by DSC method, and they were in the range of 238–279°C. These polymers were stable up to 408–449°C in air and 451–483°C in nitrogen and lose 10% weight in the range of 479–525°C in air and 480–528°C in nitrogen atmosphere. The polymer films had a tensile strength range of 71–115 MPa, an elongation at break range of 4–14%, and a tensile modulus range of 2.3–3.1 GPa. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2301–2307, 1998     

Synthesis and characterization of some halogen-containing poly(esterurethane)s

A series of halogen-containing poly (esterurethane)s was synthesized from the prepolymers, i.e., hydroxy-terminated polyesters containing chlorine and fluorine and the diisocyanates such as toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI). Polyesterification of halogenated phthalic anhydride with an excess of diols such as ethylene glycol, 1,2-propanediol, and 1,4-butanediol in the presence of trifluoroacetic anhydride (TFAA) was carried out to prepare prepolymers. The prepolymers and the poly (esterurethane)s were characterized by infrared (IR), ¹H nuclear magnetic resonance (NMR), viscosity, end-group analysis, solubility and thermal analysis namely thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Kinetics of thermal degradation was also studied. Resistance of the polymers to alkaline agents and combustion was also tested.     

New rigid-rod poly(benzoxazole-imide)s containing chloro-substituted p-phenylene units in the main chain

A series of new poly(o-hydroxy amide-imide)s with high molecular weights were synthesized by low-temperature solution polycondensation from a preformed imide ring and chloro- or dichloro-substituted p-phenylene-containing diacid chlorides of 2,5-bis(trimellitimido)chlorobenzene or 1,4-bis(trimellitimido)-2,5-dichlorobenzene and three bis(o-amino phenol)s. All the poly(o-hydroxy amide-imide)s were readily soluble in a variety of organic solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide. Transparent and flexible films of these polymers were cast from their solutions. The cast films had tensile strengths ranging from 88 to 102 MPa and elongations at break of 8–12%. Subsequent thermal cyclodehydration of the poly(o-hydroxy amide-imide)s afforded novel poly(benzoxazole-imide)s. The poly(benzoxazole-imide)s exhibited glass-transition temperatures in the range of 310–338 °C and were stable up to 500 °C in nitrogen, with 10% weight-loss temperatures recorded between 550 and 570 °C in nitrogen. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4151–4158, 1999     

Synthesis and properties of segmented main‐chain liquid‐crystalline polyurethanes with a high aspect ratio mesogenic diol as a chain extender

Main‐chain liquid‐crystalline polyurethanes were synthesized based on a high aspect ratio mesogenic diol (4‐{[4‐(6‐hydroxyhexyloxy)‐phenylimino]‐methyl}‐benzoic acid 4‐{[4‐(6‐hydroxyhexyloxy)‐phenylimino]‐methyl}‐phenyl ester) as a chain extender; polycaprolactone (PCL) diol soft segments of different number‐average molecular weights (530, 1250, or 2000); and different diisocyanates, including 1,4‐hexamethylene diisocyanate (HMDI), 4,4′‐methylene bis(cyclohexyl isocyanate) (H₁₂MDI), and 4,4′‐methylene bis(phenyl isocyanate) (MDI). The structure of the polymers was confirmed with Fourier transform infrared spectroscopy, and differential scanning calorimetry and polarizing microscopy measurements were carried out to examine the liquid‐crystalline and thermal properties of the polyurethanes, respectively. The mesogenic diol was partially replaced with 20–50 mol % PCL. A 20 mol % mesogen content was sufficient to impart a liquid crystalline property to all the polymers. The partial replacement of the mesogenic diol with PCL of various molecular weights, as well as the various diisocyanates, influenced the phase transitions and the occurrence of mesophase textures. Characteristic liquid‐crystalline textures were observed when a sufficient content of the mesogenic diol was present. Depending on the flexible spacer length and the mesogenic content, grained and threadlike textures were obtained for the HMDI and H₁₂MDI series polymers, whereas the polyurethanes prepared from MDI showed only grained textures for all the compositions. The polymers formed brittle films and could not be subjected to tensile tests. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1527–1538, 2002     

侧链含分散红类染料基团的聚(氨酯-酰亚胺)的合成与表征

采用两步法合成了4种侧链含偶氮染料发色团分散红-19的新型聚(氨酯-酰亚胺)(PUI):先合成含染料发色团的二异氰酸酯,再进一步和二酐单体缩合生成PUI.用红外光谱、紫外-可见光谱、DSC和TGA等手段对合成的PUI进行表征.所有PUI在～490nm处都有一强吸收峰.PUI可溶于强极性非质子溶剂,如NMP,DMAc,DMF,DMSO和1,4-丁内酯,有些甚至在常用的低沸点溶剂如THF中也可溶解.PUI的特性粘数在0.16～0.31dL/g范围内.其玻璃化转变温度(Tg)在171～211℃范围内,明显高于侧链型非线性光学聚氨酯(PU).以刚性相对较大的六氟异丙叉基二(3,4-邻苯二甲酸酐)(6FDA)和甲苯-2,4-二异氰酸酯(TDI)为单体的PUI具有比以二苯醚-3,3′,4,4′-四甲酸二酐(OPDA)和4,4′-二异氰酸酯二苯甲烷(MDI)为单体的PUI更高的T_g.PUI的TGA曲线上有两个明显的失重台阶,起始热分解温度大约在300℃左右.     

Amine-quinone polyurethanes. I. Preparation of polyurethane block copolymers containing 2,5–bis(N-2-hydroxyethyl-N-methylamino)-1,4–benzoquinone diol monomer

The amine-quinone monomer, 2,5–bis(N-2-hydroxyethyl-N-methylamino)-1,4-benzoqui-none (AQM-1), was prepared by the multiple-step condensation of 2-(N-methylam-ino)ethanol with benzoquinone in the presence of oxygen. This crystalline monomer was used to prepare a series of amine-quinone polyurethanes by condensation polymerization, either in the melt or in solution (THF or DMF), with a diisocyanate (MDI, TDI, or IPDI) and an oligomeric diol [poly(caprolactone) or poly(1,2-butylene glycol)]. The amine-quinone functional group was stable under the polymerization conditions, and was incorporated into the main chain, giving red-brown polyurethanes that had molecular weights in the range of 11,000–90,000 and were soluble in THF, MEK, DMF, and DMSO. The thermal properties were consistent with a two-phase morphology with an amorphous soft segment, containing the oligomeric diol, and a microcrystalline hard segment, containing AQM-1. The polymers having a low hard segment content (<50%) were rubbery (soft segment T_g <?25°C); polymers having a high hard segment content (>50%) were thermoplastic (hard segment T_g>150°C). © 1995 John Wiley & Sons, Inc.     

A Reductive homo-coupling polymerization of aromatic diisocyanates promoted by samarium iodide

The selective reductive homo-coupling polymerization of aromatic diisocyanates via one-electron transfer promoted by samarium iodide in the presence of hexamethylphosphoramide (HMPA) produced the corresponding poly(oxamide)s ( 1 ) nearly quantitatively. The ob-tained polymers were insoluble in common organic solvents. The alkylation of 1 with methyl iodide or allyl bromide in the presence of potassium tert-butoxide provided the highly soluble alkylated polymer in good yields. In either case, the alkylation was almost complete, and both N-and O-alkylation proceeded. The ratio of N-and O-methylation was found to be 64 : 36 by ¹H-NMR spectrum, and that of N- and O-allylation was 3 : 1 from ¹³C-NMR analysis. The present polymerization system could be applied to a variety of diisocyanates, including diphenylmethanediisocyanate (MDI), tolylene 2,6-diisocyanate (TDI), 2,6-naphthyl diisocyanate (NDI) and o-tolidine diisocyanate (TODI). The molecular weights of the polymers were estimated by GPC and found to be 2000–9000. The TGA measurement of the corresponding polymers showed T_d10 at 248–320°C. © 1995 John Wiley & Sons, Inc.     

Diisocyanate route as a convenient method for the preparation of novel optically active poly(amide-imide)s based on N-trimellitylimido-S-valine

A new class of optically active poly(amide-imide)s based on an α-amino acid was synthesized via direct polycondensation reaction of different diisocyanates with a chiral diacid monomer. The step-growth polymerization reactions of N-trimellitylimido-S-valine (TISV) (1) with 4,4′-methylene-bis(4-phenylisocyanate) (MDI) (2) was performed under microwave irradiation, as well as solution polymerization under graduate heating and reflux conditions. The optimized polymerization conditions for each method were performed with tolylene-2,4-diisocyanate (TDI) (3), hexamethylene diisocyanate (HDI) (4), and isophorone diisocyanate (IPDI) (5) to produce optically active poly(amide-imide)s via diisocyanate route. The resulting polymers have inherent viscosities in the range of 0.02-1.10 dL/g. Decomposition temperatures for 5% weight loss (T₅) occurred above 300 °C (by TGA) in nitrogen atmospheres. These polymers are optically active, thermally stable and soluble in amide-type solvents. Some structural characterization and physical properties of this new optically active poly(amide-imide)s are reported.     

Liquid crystalline properties of unsegmented and segmented polyurethanes synthesised from high aspect ratio mesogenic diols

A series of novel tetrad high aspect ratio mesogenic diol monomers 4-{[4-(n-hydroxyalkoxy)-phenylimino]-methyl}-benzoic acid 4-{[4-(n-hydroxyalkoxy)-phenylimino]-methyl}-phenyl ester were prepared with varying alkoxy spacer length (n=2,4,6,8,10) by reacting 4-formylbenzoic acid 4-formylphenyl ester and 4-(n-hydroxyalkoxy) anilines. Two series of thermotropic main chain liquid crystalline unsegmented polyurethanes (PUs) were obtained by the polyaddition of the mesogenic diols with hexamethylene diisocyanate (HMDI) and methylene bis(cyclohexylisocyanate) (H₁₂MDI) in dimethylformamide respectively. The effect of the incorporation of a third component namely polyol on the liquid crystalline properties of the polyurethanes was also studied. Linear segmented PUs were synthesised by a two-step block copolymerisation method. The PUs synthesised were based on six spacer mesogenic diol chain extender, soft segments poly(tetramethylene oxide)glycol (PTMG) (M_n= 650,1000,2000) and polycaprolactone diol (PCL) (M_n=530,1250,2000) of varying molecular weights and different diisocyanates including HMDI, H₁₂MDI and methylene bis(phenylene isocyanate) (MDI). Structural elucidation was carried out by elemental analysis, fourier transform infra red (FT-IR), nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectroscopy. Inherent viscosity of the unsegmented polymers measured in methanesulphonic acid at 26°C was in the range of 0.13 - 0.65 dL/g while the molecular weights and molecular weight distribution of the segmented polyruethanes was determined using gel permeation chromatography (GPC). Mesomorphic properties were studied by differential scanning calorimetry (DSC) and hot stage polarising optical microscopy and the thermal stability was determined by thermogravimetric(TG)analysis. The monomeric diols and the polyurethanes exhibited nematic texture and good mesophase stability. It was observed that the partial replacement of the mesogenic diol by the polyol of varying molecular weights influenced the phase transitions and the occurrence of mesophase textures. The phase transition temperatures of the investigated polyurethanes showed dependence on the chain length of the soft segment and on the content of the mesogen moiety. A higher content of mesogenic moiety was needed to obtain liquid crystalline property when the soft segment length was increased as observed in the case of PTMG. Grained and threaded textures were observed depending on the molecular weight of the soft segment, the mesogen content and the diisocyanate. The stress-strain analyses showed that the polymers bused on high molecular weight PTMG soft segment have elastomeric property while the PCL based PUs displayed no elastomeric property.     

Annealing effects on the thermal properties of liquid crystalline polyurethanes

This work is a continuation of our earlier investigations of liquid crystalline polyurethanes prepared from 4,4′-bis(2-hydroxyethoxy) biphenyl (BHBP), 2,4-tolylene diisocyanate (TDI), and poly (oxytetramethylene) diols (PTMO). The annealing effects on the thermal properties of the investigation polyurethanes are presented for three samples with the same BHBP content, different flexible spacer length, and different molecular weight of the polyurethanes. The annealed polyurethanes were investigated by means of DSC, and polarizing microscopy. The results of the thermal analysis show that the temperatures of phase transitions depend on the annealing temperature and time. These dependences are different for different molecular weights. © 1994 John Wiley & Sons, Inc.     

Polyurethane cationomers. I. Structure-property relationships

Polyether polyurethane cationomers are prepared using poly (tetramethylene oxide) of molecular weight 2000 as soft segments, N-methyl-diethanolamine as chain extender, glycolic acid as quaternization agent, methyl ethyl ketone as solvent, and three different diisocyanates. The three diisocyanates are 4,4′-diphenylenemethylene diisocyanate (MDI), hexamethylene diisocyanate (HDI), and toluene diisocyanate (TDI). Properties of the films cast from solutions of the three series of ionomers are studied by infrared spectroscopy, dynamic mechanical analysis, thermogravimetric analysis, differential scanning calorimetry, wide angle x-ray diffraction, and tensile elongation testing. In the un-ionized and ionized systems, the hard segments exhibit disordered and ordered arrangements, respectively. Ionization disrupts the order and produces increased cohesion in the hard domains, which have opposing effects on the tensile elongation properties. In the MDI and TDI systems, cohesion is predominant, leading to an increased tensile strength and modulus and decreased elongation at break. But in the HDI system, the disruption of the order is predominant, leading to decreased tensile strength and only insignificant reduction in the elongation at break. In the TDI system, the tensile strength is rather low, which is attributed to the poor order in the hard domains resulting from the high content of the asymmetric 2,4-isomer of the urethane.     

New poly (amide-imide) syntheses. IX. Preparation and properties of poly(amide-imide)s derived from 2,7-bis (4-aminophenoxy) naphthalene and various bis (trimellitimide)s

Eleven bis(phenoxy) naphthalene-containing poly(amide-imide)s IIIa–k were synthesized by the direct polycondensation of 2,7-bis (4-aminophenoxy) naphthalene (DAPON) with various aromatic bis (trimellitimide)s IIa–k in N-methyl-2-pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Poly (amide-imide)s IIIa–k having inherent viscosities of 0.70–1.12 dL/g were obtained in quantitative yields. The polymers containing p-phenylene or bis(phenoxy) benzene units exhibited crystalline x-ray diffraction patterns. Most of the polymers were readily soluble in various solvents such as NMP, N, N-dimethylacetamide, dimethyl sulfoxide, m-cresol, o-chlorophenol, and pyridine, and gave transparent, and flexible films cast from DMAc solutions. Cast films showed obvious yield points in the stress-strain curves and had strength at break up to 87 MPa, elongation to break up to 11%, and initial modulus up to 2.10 GPa. These poly(amide-imide)s had glass transition temperatures in the range of 255–321°C, and the 10% weight loss temperatures were recorded in the range of 529–586°C in nitrogen. The properties of poly(amideimide)s IIIa–k were compared with those of the corresponding isomeric poly (amide-imide)s III′ prepared from 2,7-bis(4-trimellitimidophenoxy) naphthalene and aromatic diamines. © 1994 John Wiley & Sons, Inc.