Segmented polyurethanes with 4,4′-bis-(6-hydroxyhexoxy)biphenyl as chain extender. Part 2. Synthesis and properties of MDI-polyurethanes in comparison with 2,4-TDI-polyurethanes

Linear segmented polyurethanes based on poly(butylene adipate)s (PBA) of different molecular weight (M_n 2000, 1000, and 600), 4,4′-diphenylmethane diisocyanate (MDI) and the mesogenic diol 4,4′-bis-(6-hydroxyhexoxy)biphenyl (BHHBP) as well as the unsegmented polyurethane consisting of MDI/BHHBP units have been synthesized and characterized by elemental analysis, ¹³C-NMR and SEC. The thermal behavior and the morphology were studied by DSC, polarizing microscopy, and DMA. The properties of the MDI-polyurethanes were discussed in relation to the BHHBP chain extended 2,4-TDI-polyurethanes and common 1,4-butanediol chain-extended MDI products. MDI polyurethanes based on PBA (M_n 2000) exhibit a glass transition temperature T_g of about −40°C independent of the hard segment content up to ∼50% hard segments. At higher hard segment contents increasing T_gs were observed. Polyurethanes, based on the shorter polyester soft segments PBA (M_n 1000 or 600), reveal an increase in the glass transition temperatures with growing hard segment content. The thermal transitions caused by melting of the MDI/BHHBP hard segment domains are found at 50 K higher temperatures in comparison with the analogous TDI products with mesogenic BHHBP/TDI hard segments. Shortening of the PBA chain length causes a shift of the thermal transitions to lower temperatures. Polarizing microscopy experiments indicate that liquid crystalline behavior is influenced by both the content of mesogenic hard segments and the chain length of the polyester. © 1996 John Wiley & Sons, Inc.     

Development of high‐performance networked polymers consisting of isocyanurate structures based on selective cyclotrimerization of isocyanates

Selective and quantitative cyclotrimerization of p‐tolylisocyanate proceeded by using sodium p‐toluenesulfinate as a catalyst and 1,3‐dimethylimidazolidinone as a solvent. Exploitation of this system to the cyclotrimerization of methylene diphenyl 4,4′‐diisocyanate (MDI) permitted formation of the corresponding networked polymer, which was selectively consisted of isocyanurate moiety and thus exhibited excellent thermal stability. Utilization of phenyl isocyanate (PhNCO) as a comonomer with varying feed ratio [MDI]₀/[PhNCO]₀ allowed successful control of flexibility of the networked polymers, while retaining its high thermal stability. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Structure-property relationships in polycaprolactone-polyurethanes

The structure-property relationships of polycaprolactone-based segmented polyurethanes were studied using differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS), wide-angle x-ray diffraction (WAXD), dynamic mechanical, and stress-strain testing. The materials studied varied in hard-segment type [4,4′-diphenylmethane diisocyanate/butanediol (MDI/BD) or 4,4′-dicyclohexyl methane diisocyanate/butanediol (H₁₂MDI/BD)], soft-segment molecular weight (830 or 2000 MW polycaprolactone), hard-segment content (23–77% by weight), and thermal history. The materials with aromatic (MDI/BD) hard segments had semicrystalline hard-segment domains, while the materials with aliphatic (H₁₂MDI/BD) hard segment had mostly amorphous domains. Materials with the shorter polycaprolactone soft segment (830 MW) exhibited thermal and mechanical behavior which indicated a considerable degree of hard- and soft-segment compatibility. The materials which contained a 2000-MW polycaprolactone soft segment exhibited better-defined microphase separation. SAXS was used to characterize the microphase structure of each system. The effects of hard-segment content and soft-segment molecular weight were similar for the aromatic (MDI) and aliphatic (H₁₂MDI) hard-segment-based block copolymers. Changing the hard segment from aromatic to aliphatic gave materials with larger interfacial area and slightly higher tensile strength. A range of morphologies between isolated hard domains in a rubbery matrix and isolated rubbery domains in a hard matrix was observed.     

Synthesis and characterization of hyperbranched polyimides with good organosolubility and thermal properties based on a new triamine and conventional dianhydrides

A triamine monomer, 1,3,5‐tris(4‐aminophenoxy)benzene (TAPOB), was synthesized from phloroglucinol and 4‐chloronitrobenzene, and it was successfully polymerized into soluble hyperbranched polyimides (HB PIs) with commercially available dianhydrides: 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4′‐oxydiphthalic anhydride (ODPA), and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA). Different monomer addition methods and different monomer molar ratios resulted in HB PIs with amino or anhydride end groups. From ¹H NMR spectra, the degrees of branching of the amino‐terminated polymers were estimated to be 0.65, 0.62, and 0.67 for 6FDA–TAPOB, ODPA–TAPOB, and BTDA–TAPOB, respectively. All polymers showed good thermal properties with 10% weight‐loss temperatures (T₁₀'s) above 505 °C and glass‐transition temperatures (T_g's) of 208–282 °C for various dianhydrides. The anhydride‐terminated HB PIs showed lower T₁₀ and T_g values than their amino‐terminated counterparts. The chemical conversion of the terminal amino or anhydride groups of the 6FDA‐based polyimides into an aromatic imido structure improved their thermal stability, decreased their T_g, and improved their solubility. The HB PIs had moderate molecular weights with broad distributions. The 6FDA‐based HB PIs exhibited good solubility even in common low‐boiling‐point solvents such as chloroform, tetrahydrofuran, and acetone. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3804–3814, 2002     

Synthesis and characterization of urethane polymers containing 2,2′-biimidazole

A heterocyclic nitrogen-containing system having substituent primary diol function, i.e., 1,1′-dihydroxethyl-2,2′-biimidazole ( I ), has been prepared and used to synthesize a series of new polyurethanes based on aromatic diisocyanates (TDI, MDI). Variation of solution polymerization parameters permitted the isolation and infrared, NMR, molecular weight, and thermal characterization of polymeric materials. Isolated polymers exhibit a linear structure and have T_g (150–170°C) and thermal stability (205–250°C for 20% weight loss) properties comparable to other typical urethane polymers. Zn²⁺ complexation was indicated by shifts in the imidazole ringmode infrared vibrational bands at 917 and 1133 cm^?1 to higher frequencies.     

Amorphous copolyesters based on bibenzoic acids and neopentyl glycol

High T_g amorphous copolyester thermoplastics were synthesized by incorporating 4,4′‐bibenzoate (4,4′BB) and 3,4′‐bibenzoate moieties into the polyester backbone via melt polycondensation. The high levels of crystallinity typically associated with 4,4′BB containing polyesters were suppressed through copolymerization of ethylene glycol, 1,4‐cyclohexane dimethanol, and neopentyl glycol (NPG) diols. NPG was shown to be highly effective in suppressing crystallization and was used to produce amorphous compositions with T_g’s as high as 129 °C. Diol ratios were determined by ¹H NMR spectroscopy and molecular weights were assessed with inherent viscosity (η_inh). Thermogravimetric analysis showed single‐step weight losses in the range of 395 – 419 °C. Differential scanning calorimetry was used to determine melting points and glass transition temperatures over a wide range of copolyester compositions and identified amorphous compositions. Dynamic mechanical analysis confirmed T_g’s and was used to study β‐relaxations below the T_g. Rheological analysis revealed the effect of NPG structures on shear thinning and thermal stability. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 579–587     

Block copolyesters of poly(pentamethylene p,p′‐bibenzoate) and poly(tetramethylene adipate)

Hydroxy‐terminated poly(pentamethylene p,p′‐bibenzoate) oligomers with different molecular weights were prepared. The poly(pentamethylene p,p′‐bibenzoate) oligomers showed rather high crystallinity, and some of them exhibited a monotropic smectic phase. Block copolyesters with hard segments of poly(pentamethylene p,p′‐bibenzoate) and soft segments of poly(tetramethylene adipate) were prepared by coupling the poly(pentamethylene p,p′‐bibenzoate) oligomer and a poly(tetramethylene adipate)glycol with methylene‐4,4′‐diphenylene diisocyanate in solution. The block copolyesters were characterized by IR, ¹H NMR, differential scanning calorimetry, a polarized microscope, and X‐ray diffraction. The thermal transitions of the block copolyesters were dependent on the composition and the molecular weight of the poly(pentamethylene p,p′‐bibenzoate) oligomer used. The hard segments in the block copolyesters showed no liquid crystallinity and exhibited rather low crystallinity or were even amorphous. The molecular weight of the poly(pentamethylene p,p′‐bibenzoate) oligomer used influences the glass‐transition temperature and crystalline properties of the soft segments in the block copolyesters significantly. The effect on the glass‐transition temperature of the soft segments is described as the difference in miscibility between the hard and soft segments. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2626–2636, 2002     

Isomorphous replacement in nylon 6 by 4-aminomethylcyclohexanecarboxylic acid

It was desired to determine the effect of geometric configuration on the ability of 4-aminomethylcyclohexanecarboxylic acid (AMCC) to “isomorphously” replace ε-aminocaproic acid residues in nylon 6. However, we found that cis-AMCC isomerized to the more thermodynamically stable trans isomer during copolymerization with caprolactam (CL) and also during homopolymerization. A 20/80 cis/trans ratio of AMCC residues was found in the 50:50 copolyamides regardless of whether a high-cis (72/28) or high-trans (15/85) AMCC was used. Powder x-ray diagrams showed similar interplanar spacings for the copolyamides made from both high-cis and high-trans AMCC. The x-ray study also showed that the nylon 6 lattice can accommodate less than 30 mole-% AMCC residues before a new structure appears. DTA and TGA data of the CL:AMCC copolyamide showed that AMCC raised the melting point, T_g, T_c, and stability of nylon 6.     

Dynamic mechanical relaxation effects in some poly(arylene sulfones)

Poly-4,4′-oxydiphenylenesulfonyl and poly-4,4′-methylenediphenylenesulfonyl were synthesized by an electrophilic substitution polymerization of the arylene monosulfonyl chloride monomers. The glass-transition temperatures T_g of these polymers were determined by calorimetric and dynamic mechanical measurements, and the number-average molecular weights were determined by vapor-pressure osmometry. Both polymers were found to have the same T_g at equivalent molecular weight; the limiting value at high molecular weight is 238°C. Both polymers have two dynamic mechanical relaxation peaks at temperatures far below T_g. One is in the neighborhood of 0°C, and the other is at ?110°C. Plausible origins for these relaxations, and the absence of any near 0°C in poly(4,4′-isopropylidenediphenylene-co-4,4′-sulfonyldiphenylene dioxide), are discussed.     

Synthesis of block copolymer with polystyrene and nylon units

Bis-ε-aminocaproylaminocaproylhexamethylenediamine ( I ) was synthesized as an analog of 6-nylon pentamer diamine, and its incorporation into block copolymers was studied with the use of α,ω-dihydroxyl, α,ω-bisdimethylchlorosilyl, and α,ω-diepoxy polystyrene. In the course of the experiments, the stability and the reactivity of 4,4′-diphenylmethane diisocyanate and tetramethylene diisocyanate in aprotic dipolar solvents were examined by infrared spectroscopy. The only usable solvent, N-methylpyrrolidone, was found still inadequate for the synthesis involving I, diisocyanate, and α,ω-dihydroxyl polystyrene. A block copolymer having M _n = 18,000 was obtained by the reaction of I and α,ω-diepoxy polystyrene. All T_g values of the block copolymers were above 90°C, higher than for polystyrenes with corresponding molecular weight.     

Solid-state 13C nuclear magnetic resonance characterization of MDI-based polyurethanes

¹³C solid-state nuclear magnetic resonance (NMR) experiments on linear polyurethanes and poly(ether-urethane) block copolymers demonstrate that ¹³C spin-lattice relaxation experiments in the laboratory [T₁(C)] and rotating [T_1p(C)] frames provide the most information about domain morphology in these microphase-separated polymer systems. T₁(H) TCH, and T_1p(H) data are less useful in a 4,4′-methylene bis(p-phenyl isocyanate)-1,4-butanediol (MDI/BD) hard-segment material, the MDI bridging methylene and the MDI urethane carbonyl T₁(C and T_1p(C) times fall in characteristic ranges for crystalline, amorphous, interfacial, and dissolved species. BD methylene carbons have short T_1p(C) for crystalline and long T_1p(C) for amorphous hard-segment aggregates. The distinct T_1p(C) and T₁(C) fractins observed are attributed to the presence of several crystalline polymorphs. Both T₁(C) results and DSC endotherms indicate that the crystalline polymorphs present in the poly(ether-urethane) are less ordered than the types seen in the pure hard-segment material. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of 3-phenylethynyl endcapped matrix resins

The synthesis of 3-phenylethynylphenol, and its applicability as a high temperature cross-linking endcap for high T_g polyarylene ethers is described. It was synthesized in high yields and purity using the palladium catalyzed coupling reaction between the protected 3-bromo or iodo phenol and phenylacetylene. The yield of the reaction was found to be highly dependent on the structure of the halide used, the reaction temperature, and the concentration of phenylacetylene. The use of the protected phenol in the palladium catalyzed reaction was also extended to the high yield synthesis of 3-ethynylphenol and protected 4-ethynylphenols. The complete synthesis of 3-phenylethynylphenol, 3-ethynylphenol, and protected 4-ethynylphenol in high yields has been demonstrated and is discussed herein. Three new phenylethynyl functionalized arylene ether matrix resins have been synthesized in high yields and purity by reacting 3-phenylethynylphenol with 4,4′-dichlorodiphenyl sulfone, 4,4′-difluorobenzophenone, and bis(4-fluorophenyl)phenyl phosphine oxide, via nucleophilic poly(arylene ether) synthesis conditions. These low molecular weight materials undergo thermally induced chain extension/branching to yield an insoluble three-dimensional network at reaction temperatures of around 380°C. The low molecular weight arylene ethers endcapped with the phenylethynyl group demonstrate excellent flow characteristics and a wide processing window of about 250°C. Crosslinking of the 4,4′-bis(3-phenylethynyl phenoxy)diphenyl sulfone system for 30 min at 350°C in air afforded a T_g value of 265°C by differential scanning calorimetry measurements. Trace metal analysis for palladium and copper showed absence of these metals that would otherwise detract from the excellent thermal stability. The synthesis and characterization of these phenylethynyl endcapped arylene ether matrix resins is discussed. © 1995 John Wiley & Sons, Inc.     

Preparation of silicon containing polymers. II.. Effect of structure on the thermal stability of organosilicon aramids

Two silicon-containing acid dichlorides, bis(4-chlorocarbonylphenyl)dimethylsilane and bis(4-chlorocarbonylphenyl)diphenylsilane, were synthesized and reacted with 1,3-phenylene diamine, 1,4-phenylene diamine, 4,4′-diaminodiphenyl, 4,4′-diaminodiphenyl methane 4,4′-diaminodiphenyl ether, and 4,4′-diaminodiphenyl sulfone in the preparation of 12 structurally different high molecular weight aromatic polyamides. A low-temperature interfacial polycondensation technique was used. Most of the polyamides formed tough, transparent, flexible films and were characterized by solubility, solution viscosity, infrared spectroscopy (IR), and glass transition temperature (T_g). The thermal behavior of these aramids was studied by dynamic thermogravimetry. The effect of diamine and acid dichloride structure on the aramids properties is also discussed.     

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     

Fully imidized soluble polyimides based on a novel dianhydride: 2,2′-dichloro-4,4′,5,5′-benzophenone tetracarboxylic dianhydride

We have synthesized a novel dianhydride, 2,2′-dichloro-4,4′,5,5′-benzophenone tetracarboxylic dianhydride (DCBTDA). Polyimides were synthesized with DCBTDA or 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and several relatively rigid meta- and para- substituted mononuclear diamines. The BTDA based systems were insoluble in dipolar, aprotic solvents whereas the DCBTDA based polymers displayed enhanced solubility in these solvents. The thermal stability of these polyimides was excellent as measured by 5% weight loss decomposition. The T_g's of the polymers were all above 290°C.     

Thermal properties of poly-ε-caprolactam and copolyamides based on ε-caprolactam

The copolyamides consisting of ε-caprolactam and 6.1–24.5 wt.% of nylon salt prepared from adipic acid and 1-(2-aminoethyl) piperazine were synthesized. Physical and thermal characteristics of polyamide 6 and the copolyamides were compared. Nylon salt does not influence the polyreaction equilibrium so it is possible to prepare the copolyamides with high molecular weight and with the content of low-molecular compounds comparable with that of pure PA 6. Melting temperatures of the copolyamides are lower in comparison with PA 6 and decrease proportionally to the amount of the nylon salt. The thermal stability of the copolyamides is good and equal to that of PA 6. The melting enthalpies indicate that the process of crystallization of the copolyamides is influenced by the time of crystallization and the amount of comonomer present. Longer time of the crystallization assures higher degree of crystallization. The kinetics and the level of crystallization are positively influenced by the mobility of copolyamide segments mainly up to 10 wt.% of comonomer.     

Synthesis and characterization of aromatic polythiazole-amides from new aromatic diamines containing phenyl-pendant thiazole units

New aromatic diamines containing phenyl-pendant thiazole units were synthesized in three steps starting from p-nitrobenzyl phenyl ketone. Novel aromatic polyamides containing phenyl-pendant thiazole units were prepared by the low-temperature solution polyconden-sation of 1,4- (or 1.3-) bis[5-(p-aminophenyl)-4-phenyl-2-thiazolyl] benzene with various aromatic dicarboxylic acid chlorides in N,N-dimethylacetamide. High molecular weight polyamides having inherent viscosities of 0.5–3.0 dL/g were obtained quantitatively. The polythiazole-amides with m-phenylene, 4,4′-oxydiphenylene, and 4,4′-sulfonyldiphenylene units were soluble in N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and pyridine, and gave transparent flexible films by casting from the solutions. These organic solvent-soluble polyamides displayed prominent glass transition temperatures (T_g) between 257 and 325°C. On the other hand, the polythiazole-amides with p-phenylene and 4,4′-biphenylene units were insoluble in most organic solvents, and had no observed T_g. All the polythiazole-amides started to decompose at about 400°C with 10% weight loss being recorded at 450–525°C in air. © 1995 John Wiley & Sons, Inc.     

Structure analysis of polyether-based thermoplastic polyurethane elastomers by FTIR, 1H NMR and 13C NMR

One kind of unknown structure sequence and composition ratio of thermoplastic polyurethane elastomers were characterized by nuclear magnetic resonance spectroscopy, Fourier transformed infrared spectroscopy, and gel permeation chromatography (GPC). The results showed that the polyurethane (PU) was obtained from poly(tetramethylene glycol) (PTMG) as soft segment, 1,4-butanediol (BDO) as chain extender, and 4,4′-methylenediphenyl diisocyanate (MDI) as hard segment. Furthermore, the composition ratio of MDI:PTMG:BDO was 2.07:1.22:1.00. At last, the molecular weight of PU was determined by GPC, and the number average molecular weight (M_n) and weight average molecular weight (M_w) are 63,300 and 133,800?g?mol^?1, respectively.     

Thermal properties of PA 6 and PA 6 modified with copolyamides and layered silicates

This article focuses on the thermal properties of PA 6 and additives, i.e. ternary copolyamides, concentrates consisting of binary or ternary copolyamides + nanoadditive montmorillonite Bentonite 11958 or Cloisite 15A and PA 6 fibres modified with Bentonite, copolyamide and concentrate. The copolyamides are prepared from ε-caprolactam as a major comonomer and nylon salts AN2 from adipic acid + 1-(2-aminoethyl)piperazine and ADETA from adipic acid + diethylenetriamine. All copolyamides and concentrates exhibit lower melting temperatures T _m and lower melting enthalpies ΔH _m compared to neat PA 6. PA 6 fibres modified with 0.25–2.5 wt% MMT exhibit higher melting enthalpies in comparison with unmodified PA 6 fibres. PA 6 fibres modified with 10 wt% of ternary copolyamide containing 21.4 wt% of comonomers AN2 and ADETA have higher melting enthalpy as well. PA 6 fibres modified with 10 and 20 wt% of concentrate containing the same ternary copolyamide + 5 wt% of MMT have higher melting enthalpies and higher tensile strength in comparison with these characteristics of unmodified PA 6 fibres.     

Parameters affecting transition temperatures of poly(lactic acid‐co‐polydiols) copolymer‐based polyester urethanes and their shape memory behavior

A series of polyester urethanes (PEUs) comprising poly(lactic acid‐co‐polydiol) copolymers as a soft segment, 4,4′‐diphenylmethane diisocyanate (MDI) and 1,4‐butanediol (BDO) as a hard segment were systematically synthesized. Soft segments, which were block copolymers of L ‐lactide (LA) and polydiols such as poly(ethylene glycol) and poly(trimethylene ether glycol), were prepared via ring opening polymerization. Glass transition temperatures (T_g) of the obtained PEUs were found strongly dependent on properties of copolymer soft segments. By simply changing composition ratio, type and molecular weight of polydiols in the soft segment preparation step, T_g of PEU can be varied in the broad range of 0–57°C. The synthesized PEUs exhibited shape memory behavior at their transition temperatures. PEUs with hard segment ratio higher than 65 mole percent showed good shape recovery. These findings suggested that it is important to manipulate molecular structure of the copolymer soft segment for a desirable transition temperature and design optimal soft to hard segment ratio in PEU for good shape recovery. Copyright © 2011 John Wiley & Sons, Ltd.