Novel method for preparation of poly(benzoxazinone‐imide)

A novel method was developed to prepare poly(benzoxazinone‐imide) by the dealcoholization of poly(amide‐imide), having pendent ethoxycarbonyl groups, which was prepared from poly(amide acid). The poly(amide acid) was prepared from the reaction of pyromellitic dianhydride and 4,4′‐diamino‐6‐ethoxycarbonyl benzanilide. The curing behavior of the poly(amide acid) was monitored by DSC, which indicated the presence of two broad endotherms, one with maximum at 153 °C due to imide‐ring formation and the other with maximum at 359 °C due to benzoxazinone‐ring formation. The poly(amide acid) was thermally treated at 300 °C/1 h to get poly(amide‐imide) with pendent ester groups, then at 350 °C/2 h to convert into poly(benzoxazinone‐imide) by dealcoholization. Viscoelastic measurements of the poly(amide‐imide) showed that the storage modulus dropped at about 280 °C with glass‐transition temperature (T_g ) at about 340 °C. The storage modulus of poly(benzoxazinone‐imide), however, was almost constant up to 400 °C and no T_g was detected below 400 °C. Also, the tensile modulus and tensile strength of the poly(benzoxazinone‐imide) was much higher than that of the poly(amide‐imide). The 5% decomposition of poly(benzoxazinone‐imide) film was at 535 °C, which reflects its excellent thermal stability. Also, poly(benzoxazinone‐imide) showed more hydrolytic stability against alkali in comparison to polyimides. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1647–1655, 2000     

Effect of multiple H‐bonding on the properties of polyimides containing the rigid rod groups

To investigate the influence of hydrogen bonding on the properties of polyimides (PIs) containing rigid rod‐like groups, five symmetrical diamines containing benzimidazole, benzoxazole, and hydroxy group were synthesized, and then a series of PIs were prepared. Results showed that hydroxyl‐containing poly(benzoxazole imide)s possess higher glass transition temperature (T_g) and dimensional stabilities than their corresponding poly(benzoxazole imide)s. Moreover, the corresponding poly(benzimidazole imide)s presented the best performances, such as the highest T_g, the highest char yield and the highest dimensional stabilities. The influence of hydrogen bonding of benzimidazole on the properties of PIs was stronger than that of hydroxyl groups. Hydroxyl‐containing poly(benzoxazole imide)s were formed in crosslinking structures after heat treatment at 400 °C. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 570–581     

Novel heterocyclic poly(pyridine‐imide)s with unsymmetric carbazole substituent and noncoplanar structure: High thermal,mechanical and optical transparency,electrochemical, and electrochromic properties

A diamine containing heterocyclic pyridine and unsymmetrical carbazole substituents, 4‐(9‐ethyl‐3‐carbazole)‐2,6‐bis(4‐aminophenyl)pyridine ( CBAPP ), was prepared for use in the synthesis of poly(pyridine‐imide)s PI‐1–8 by direct polycondensation with dianhydrides in N,N‐dimethylacetamide (DMAc). The poly(pyridine‐imide)s derived from the diamine are highly soluble in solvents such as N‐Methyl‐2‐pyrrolidone (NMP) and DMAc at room temperature. Noncoplanar polyimide (PI‐1) showed excellent solubility, high transparency, and high‐performance mechanical properties. These polymers had relatively high glass transition temperatures and exhibited good thermal stability in both nitrogen (T_d10 > 470 °C) and air (T_d10 > 450 °C). The PI‐3～5 cannot form flexible and tough films due to the unsymmetrical carbazole moiety, rigid structure, and polar–polar interaction. However, through copolymerization technique these polymers (PI‐6～8) could be enhanced through the solubility, mechanical, and thermal properties. The optical properties included a strong orange fluorescence (540 nm) after protonation with acid. When the HCl concentration was increased, a new absorption band at approximately 350 nm appeared, and the intensity of the fluorescent peak at 380 nm observed in the neutral polymer solution decreased, along with the appearance of the new fluorescent peak at 540 nm. The poly(pyridine‐imide)s presented here showed only slight fluorescence quenching in the presence of methanol. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 405–412     

Thiol–ene polymerizations using imide‐based monomers

New diene and dithiol monomers, based on aromatic imides such as benzophenone‐3,3′,4,4′‐tetracarboxylic diimide were synthesized and used in thiol‐ene polymerizations which yield poly(imide‐co‐thioether)s. These linear polymers exhibit limited solubility in various organic solvents. The molecular weights of the polymers were found to decrease with increasing imide content. The glass transition temperature (T_g) of these polymers is dependent on imide content, with T_g values ranging from ?55 °C (with no imide) up to 13 °C (with 70% imide). These thermal property improvements are due to the H‐bonding and rigidity of the aromatic imide moieties. Thermal degradation, as studied by thermogravimetric analysis, was not significantly different to the nonimide containing thiol‐ene polymers made using trimethyloylpropane diallyl ether and 3,5‐dioxa‐1,8‐dithiooctane. It is expected that such monomers may lead to increased glass transition temperatures in other thiol‐ene polymer systems as these normally exhibit low glass transition temperatures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4637–4642     

Thermo‐/moisture‐responsive shape‐memory effect of poly(2‐ethyl‐2‐oxazoline) networks

In this work, poly(2‐ethyl‐2‐oxazoline) (PEtOx) is crosslinked to realize a moisture‐ and thermo‐responsive shape‐memory polymer. The obtained PEtOx networks exhibit excellent shape‐memory properties with storable strains of up to 650% and recovery values of 100% over at least 10 shape‐memory cycles. The trigger temperature (T_trig) of 68 °C of a PEtOx network at a relative humidity (RH) of 0% decreases with increasing moisture and equals room temperature at an RH of 40%. Thus, programmed PEtOx networks trigger sensitively on a certain temperature/moisture combination and, further, can be programmed as well as triggered at room temperature exclusively by varying humidity. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1053–1061     

Fluorene based donor‐acceptor polymer electrets for nonvolatile organic transistor memory device applications

Fluorene based donor‐acceptor polyimides, including poly[bis‐(4‐aminophenyl)fluorene‐hexanediamide] [PA(BAP F‐AC)], poly[bis‐(4‐aminophenyl)fluorene‐hexafluoroisopropylidenediphthalimide] [PI(BAPF‐6FDA)], poly[bis‐(4‐aminophenyl)fluorene‐oxydiphthalimide] [PI(BAPF‐ODPA)], and poly[bis‐(4‐aminophenyl)fluorene‐1,2,4,5‐cyclohexanetetracarboxylic diimide] [PI(BAPF‐HPMDA)], as charge storage layer (electret) are employed for nonvolatile memory device applications. The polyimides are consisted of electron‐donating fluorene diamine moiety (BAPF) and neutral (AC and HPMDA) or electron‐accepting (6FDA and ODPA) moieties, respectively. The memory characteristics of these devices can be tuned from the EORM (erase once and read many times) behavior [PA(BAPF‐AC)], semi‐flash [PI(BAPF‐ODPA)], [PI(BAPF‐HPMDA)], to a flash type memory [PI(BAPF‐6FDA)]. The PI(BAPF‐6FDA) devices show the largest memory window of 77 V and a long retention time over 10⁴ s with a high I_on/I_off current ratio of 10⁸. This is attributed to the largest torsion angle of PI(BAPF‐6FDA) stabilizing charge transfer (CT) complexes. The write‐read‐erase‐read cycles were stably operated over 100 cycles. This work provides a new insight into the relationship between the CT effect and the nonvolatile memory behavior. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 602–614     

Actuation design for high‐performance shape memory polyurethanes

A series of shape memory polyurethanes were synthesized from poly(tetramethylene glycol), 4,4‐methylene diphenyl diisocyanate, and 1,3‐butanediol. The prepolymers with different molecular weights (M_c) were capped with 2‐hydroxyl ethylacrylate or 3‐aminopropyltriethoxysilane (APTES) and crosslinked by UV curing or a sol–gel reaction. Variations of the crosslinker functionality (f), subchain density (N), and hard segment content (HSC) produced systematic variations of the glass transition temperature (6–45 °C), accompanied by changes in the mechanical, dynamic mechanical and shape memory properties. More than 95% of shape fixity and 98% of shape recovery up to the fourth cycles were obtained with APTES crosslinked 3000M_c with 30% of HSC. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1473–1479     

Polycyclic arene‐based D–A polyimide electrets for high‐performance n‐type organic field effect transistor memory devices

We report the memory characteristics of n‐type N,N′‐bis(2‐phenylethyl)‐perylene‐3,4:9,10‐tetracarboxylic diimide‐based organic field‐effect transistors (OFET) using a series of donor–acceptor (D–A) polyimide electrets of poly[4,4′‐diamino‐4″‐methyltriphenylamine‐hexafluoroisopropylidenediphthal imide] ( PI(AMTPA‐6FDA) ), poly[N,N‐bis‐(4‐aminophenyl)‐aminonaphthalene‐hexafluoroisopropylidenediphthalimide] ( PI(APAN‐6FDA) ), and poly[N,N‐bis‐(4‐aminophenyl)‐aminopyrene‐hexafluoroisopropylidenediphthalimide] ( PI(APAP‐6FDA) ). Among the polymer electrets, the OFET memory device based on PI(APAP‐6FDA) exhibits the largest memory window of 40.63 V and the best charge retention ability (maintained for over 10⁴ s with the ON/OFF current ratio about 10³) due to introducing polycyclic arene functionality of pyrene into the electron donating moiety. With the excellent carrier delocalization, pyrene successfully enhanced the charge storage ability and sustained the CT complex. Besides, PI(APAP‐6FDA)‐based OFET memory also performed well in the write‐read‐erase‐read tests for over 100 cycles. Our finding may provide a new approach for the preparation of high performance nonvolatile OFET memories with electrets of D–A polyimide systems. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 139–147     

New poly(amide–imide)s syntheses. XXIII. Synthesis and properties of poly(amide–imide)s derived from 4,4′‐[1,4‐phenylenebis(isopropylidene‐1,4‐phenyleneoxy)]dianiline and various bis(trimellitimide)s

A series of poly(amide–imide)s III_a–m containing flexible isopropylidene and ether groups in the backbone were synthesized by the direct polycondensation of 4,4′‐[1,4‐phenylenebis(isopropylidene‐1,4‐phenyleneoxy)]dianiline (PIDA) with various bis(trimellitimide)s II_a–m in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. The resulting poly(amide–imide)s had inherent viscosities in the range of 0.80–1.36 dL/g. Except for those from the bis(trimellitimide)s of p‐phenylenediamine and benzidine, all the polymers could be cast from DMAc into transparent and tough films. They exhibited excellent solubility in polar solvents. The 10% weight loss temperatures of the polymers in air and in nitrogen were all above 495°C, and their T_g values were in the range of 201–252°C. Some properties of poly(amide–imide)s III were compared with those of the corresponding poly(amide–imide)s V prepared from the bis(trimellitimide) of diamine PIDA and various aromatic diamines. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 69–76, 1999     

Effect of comonomer on thermal/mechanical and shape memory property of L‐lactide‐based shape‐memory copolymers

In this study, three kinds of L ‐lactide‐based copolymers, poly(lactide‐co‐glycolide) (PLGA), poly(lactide‐co‐p‐dioxanone) (PLDON) and poly(lactide‐co‐caprolactone) (PLC), were synthesized by the copolymerization of L ‐lactide (L) with glycolide (G), or p‐dioxanone (DON) or ε‐caprolactone (CL), respectively. The copolymers were easily soluble in common organic solvents. The compositions of the copolymers were determined by ¹H‐NMR. Thermal/mechanical and shape‐memory properties of the copolymers with different comonomers were compared. Moreover, the effect of the chain flexibility of the comonomers on thermal/mechanical and shape‐memory properties of the copolymers were investigated. The copolymers with appropriate lactyl content showed good shape‐memory properties where both the shape fixity rate (R_f)and the shape recovery rate (R_r) could exceed 95%. It was found that the comonomers with different flexible molecular chain have different effects on their thermal/mechanical and shape‐memory properties. Among them, PLGA has the highest mechanical strength and recovery rate while PLC copolymer has high recovery rate when the lactyl content exceeded 85% and the lowest transition temperature (T_trans). Copyright © 2007 John Wiley & Sons, Ltd.     

Partially bio‐based poly(amide imide)s by polycondensation of aromatic diacylhydrazides based on lignin‐derived phenolic acids and aromatic dianhydrides: Synthesis,characterization, and computational studies

Two new bio‐based diacylhydrazide monomers, namely, 4,4′‐(propane‐1,3‐diylbis(oxy))bis(3‐methoxybenzohydrazide) and 4,4′‐(propane‐1,3‐diylbis(oxy))bis(3,5‐dimethoxybenzohydrazide) were synthesized starting from lignin‐derived phenolic acids, namely, vanillic acid and syringic acid. A series of poly(amide imide)s was synthesized by polycondensation of these diacylhydrazide monomers with commercially available aromatic dianhydrides. Poly(amide imide)s showed inherent viscosity in the range 0.44–0.56 dL g^?1 and exhibited good solubility in organic solvents. Poly(amide imide)s could be cast into transparent, flexible, and tough films from their N ,N‐dimethylacetamide solutions. Poly(amide imide)s showed 10% weight loss in the temperature range 340–364 °C indicating their good thermal stability. Glass transition temperature (T _g) of poly(amide imides)s were measured by DSC and DMA which were in the range 201–223 °C and 214–248 °C, respectively. The T _g values of poly(amide imide)s were dependent on the number methoxy substituents on aromatic rings of diacylhydrazide monomers. Molecular dynamics simulation studies revealed that chain rigidity is the dominant factor for observed trends in T _g. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3636–3645     

Biodegradable shape‐memory polymer—polylactide‐co‐poly(glycolide‐co‐caprolactone) multiblock copolymer

In this study, biodegradable shape‐memory polymers—polylactide‐co‐poly(glycolide‐co‐caprolactone) multiblock (PLAGC) copolymers—were synthesized by the coupling reaction of both macrodiols of polylactide (PLLA‐diol) and poly(glycolide‐co‐caprolactone) (PGC‐diol) in the presence of 1,6‐hexanediisocyanate as coupling agent. The copolymers formed were found to be thermoplastic and easily soluble in common solvents. The compositions of the copolymers were determined by ¹H‐NMR and the influences of segment lengths and contents of both macrodiols on the properties of the PLAGC copolymers were investigated. It was found that the copolymers had adjustable mechanical properties which depended on contents and segment lengths of both macrodiols. The copolymers showed such good shape‐memory properties that the strain fixity rate (R_f) and the strain recovery rate (R_r) exceed 90%. By means of adjusting the compositions of the copolymers, PLAGC copolymers with transition temperatures around 45°C could be obtained. The degradation rate determination showed that the PLAGC copolymers have fast degradation rates, the mechanical strengths of the PLAGC copolymers would be completely lost within 1–2 months depending on molecular weights and contents of the both segments of PLLA and PGC. Copyright © 2005 John Wiley & Sons, Ltd.     

Facile synthesis of high‐performance poly(pyrrolone imide)s from an unsymmetric phosphinated triamine

High‐performance and flexible poly(pyrrolone imide)s (PPyIs) were firstly prepared by the reaction of dianhydrides with an unsymmetric phosphinated triamine, 1‐(3,4‐diaminophenyl)‐1‐(4‐aminophenyl)‐1‐(6‐oxido‐6H ‐dibenz <c,e> <1,2> oxaphosphorin‐6‐yl)ethane (1), which was prepared by a facile, one‐pot procedure from the reaction DOPO, 4‐aminoacetophenone in excess o‐phenylenediamine in the presence of p‐toluenesulfonic acid. Thermal properties of the resulting PPyIs were evaluated and compared with those of phosphinated polyimides with a similar structure. All of the prepared PPyIs films are tough and creasable. They display higher T_g (374–412 °C), lower coefficient of thermal expansion (34–46 ppm/°C), and better thermal stability (T_d 5 wt %: 456–477 °C, 800 °C char yield: 59–63%) than analogous phosphinated polyimides. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2709–2715     

Preparation and properties of new poly(amide‐imide)s based on 1,4‐bis(4‐trimellitimidophenoxy)naphthalene and aromatic diamines

A diimide dicarboxylic acid, 1,4‐bis(4‐trimellitimidophenoxy)naphthalene (1,4‐BTMPN), was prepared by condensation of 1,4‐bis(4‐aminophenoxy)naphthalene and trimellitic anhydride at a 1 : 2 molar ratio. A series of novel poly(amide‐imide)s (IIa–k) with inherent viscosities of 0.72 to 1.59 dL/g were prepared by triphenyl phosphite‐activated polycondensation from the diimide‐diacid 1,4‐BTMPN with various aromatic diamines (Ia–k) in a medium consisting of N‐methyl‐2‐pyrrolidinone (NMP), pyridine, and calcium chloride. The poly(amide‐imide)s showed good solubility in NMP, N,N‐dimethylacetamide, and N,N‐dimethylformamide. The thermal properties of the obtained poly(amide‐imide)s were examined with differential scanning calorimetry and thermogravimetry analysis. The synthesized poly(amide‐imide)s possessed glass‐transition temperatures in the range of 215 to 263°C. The poly(amide‐imide)s exhibited excellent thermal stabilities and had 10% weight losses at temperatures in the range of 538 to 569°C under a nitrogen atmosphere. A comparative study of some corresponding poly(amide‐imide)s also is presented. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1–8, 2000     

Synthesis and characterization of photocrosslinked poly(ε‐caprolactone)s showing shape‐memory properties

Poly(ε‐caprolactone) (PCL) with a pendent coumarin group was prepared by solution polycondensation from 7‐(3,5‐dicarboxyphenyl) carbonylmethoxycoumarin dichloride and α, ω‐dihydroxy terminated poly(ε‐caprolactone) with molecular weights of 1250, 3000, and 10,000 g/mol. These photosensitive polymers underwent a rapid reversible photocrosslinking upon exposure to irradiation with alternating wavelengths (>280/254 nm) without a photoinitiator. The thermal and mechanical properties of the photocrosslinked films were examined by means of differential scanning calorimetry and stress–strain measurements. The crosslinked films exhibited elastic properties above the melting temperature of the PCL segment along with significant decrease in the ultimate tensile strength and Young's modulus. Shape‐memory properties such as strain fixity ratio (R_f) and strain recovery ratio (R_r) were determined by means of a cyclic thermomechanical tensile experiments under varying maximum strains (ε_m = 100, 300, and 500%). The crosslinked ICM/PCL‐3000 and ‐10,000 films exhibited the excellent shape‐memory properties in which both R_f and R_r values were 88–100% for tensile strain of 100–500%; after the deformation, the films recovered their permanent shapes instantaneously. In vitro degradation was performed in a phosphate buffer saline (pH 7.2) at 37 °C with or without the presence of Pseudomonas cepacia lipase. The presence of the pendent coumarin group and the crosslinking of the polymers pronouncedly decreased the degradation rate. The crosslinked biodegradable PCL showing a good shape‐memory property is promising as a new material for biomedical applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2422–2433, 2009     

Synthesis,structure, and properties of polyimide and polyurethane‐urea‐imide copolymers

Several, novel polyimide–polyurethane‐urea‐imide (PI‐PUI) copolymers with different polyimide (PI) contents were prepared by an in situ interpenetrating reaction between polyurethane‐urea‐imide (PUI) precursor and poly(amide acid). Changing the ratio of the PUI precursor and poly(amide acid) resulted in a change of the properties of the PI‐PUI copolymers from plastic to elastomer. Fourier transform infrared spectra revealed the characteristic absorption bands of PI‐PUI copolymers; differential scanning calorimetry (DSC) analyses revealed that the glass‐transition temperature of the soft‐segment‐rich phase decreased as the PI content increased in PI‐PUIs, meaning that the soft segments (i.e., PEG) were more incompatible and had better crystallizability with a high‐PI‐segment content in PI‐PUI. Wide‐angle X‐ray diffraction curves exhibited more ordered structure within the disordered PI‐PUI copolymer's state with an increasing PI content, which further agreed with the DSC results. Scanning electron micrographs clearly showed that the molecular chains in PI‐PUI with a high‐PI‐content packed, ordered lamellar structure. Thermogravimetric curves indicated that the heat resistance of PI‐PUI was better than pure PUI. The introduction of the PI component into PUI by an in situ interpenetrating reaction method is an effective way to improve the thermal stability and solvent resistance of PUI. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 216–225, 2004     

Hierarchically organized micellization of thermoresponsive rod‐coil copolymers based on poly[oligo(ethylene glycol) methacrylate] and poly(ε‐caprolactone)

A series of amphiphilic triblock copolymers, poly[oligo(ethylene glycol) methacrylate]_x‐block‐poly(ε‐caprolactone)‐block‐poly[oligo(ethylene glycol) methacrylate]_x, POEGMA_Co(x), were synthesized. Formation of hydrophobic domains as cores of the micelles was studied by fluorescence spectroscopy. The critical micelle concentrations in aqueous solution were found to be in the range of circa 10^?6 M. A novel methodology by modulated temperature differential scanning calorimetry was developed to determine critical micelle temperature. A significant concentration dependence of cmt was found. Dynamic light scattering measurements showed a bidispersed size distribution. The micelles showed reversible dispersion/aggregation in response to temperature cycles with lower critical solution temperature between 75 and 85 °C. The interplay of the two hydrophobic and one thermoresponsive macromolecular chains offers the chance to more complex morphologies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and characterization of soluble polyimides derived from 2′,5′‐bis(3,4‐dicarboxyphenoxy)‐p‐terphenyl dianhydride

A novel bis(ether anhydride) monomer, 2′,5′‐bis(3,4‐dicarboxyphenoxy)‐p‐terphenyl dianhydride, was synthesized from the nitro displacement of 4‐nitrophthalonitrile by the phenoxide ion of 2′,5′‐dihydroxy‐p‐terphenyl, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and cyclodehydration of the resulting bis(ether diacid). A series of new poly(ether imide)s bearing laterally attached p‐terphenyl groups were prepared from the bis(ether anhydride) with various aromatic diamines via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s followed by thermal or chemical imidization to the poly(ether imide)s. The inherent viscosities of the poly(amic acid) precursors were in the range of 0.62–1.26 dL/g. Most of the poly(ether imide)s obtained from both routes were soluble in polar organic solvents, such as N,N‐dimethylacetamide. All the poly(ether imide)s could afford transparent, flexible, and strong films with high tensile strengths. The glass‐transition temperatures of these poly(ether imide)s were recorded as between 214 and 276 °C by DSC. The softening temperatures of all the poly(ether imide) films stayed in the 207–265 °C range according to thermomechanical analysis. For all the polymers significant decomposition did not occur below 500 °C in nitrogen or air atmosphere. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1008–1017, 2004     

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     

Influence of programming strain rates on the shape‐memory performance of semicrystalline multiblock copolymers

Multiblock copolymers named PCL‐PIBMD consisting of crystallizable poly(ε‐caprolactone) segments and crystallizable poly[oligo(3S‐iso‐butylmorpholine‐2,5‐dione)] segments coupled by trimethyl hexamethylene diisocyanate provide a versatile molecular architecture for achieving shape‐memory effects (SMEs) in polymers. The mechanical properties as well as the SME performance of PCL‐PIBMD can be tailored by the variation of physical parameters during programming such as deformation strain or applied temperature protocols. In this study, we explored the influence of applying different strain rates during programming on the resulting nanostructure of PCL‐PIBMD. Programming was conducted at 50 °C by elongation to ε_m = 50% with strain rates of 1 or 10 or 50 mm min^?1. The nanostructural changes were visualized by atomic force microscopy (AFM) measurements and investigated by in situ wide and small angle X‐ray scattering experiments. With increasing the strain rate, a higher degree of orientation was observed in the amorphous domains. Simultaneously the strain‐induced formation of new PIBMD crystals as well as the fragmentation of existing large PIBMD crystals occurred. The observed differences in shape fixity ratio and recovery stress of samples deformed with various strain rates can be attributed to their different nanostructures. The achieved findings can be relevant parameters for programming the shape‐memory polymers with designed recovery forces. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1935–1943