Alternating poly(ester amide)s of glycolic acid and ω‐amino acids: Crystalline morphology and main crystallographic data

The unit cell parameters of two alternating poly(ester amide)s constituted by glycolic acid and ω‐amino acid units have been determined by interpretation of X‐ray and electron diffraction patterns. Orthorhombic unit cells containing two chain segments with a nonplanar conformation have been derived. The electron diffraction patterns were rather different from those characteristic of aliphatic polyamides and polyesters with a zig–zag conformation. Chain‐folded lamellar crystals have been obtained by isothermal crystallization of dilute diol or glycerine solutions and the crystalline habit has been studied by means of real space electron microscopy. Polyethylene decoration techniques have been applied to evaluate the regularity of the folding surfaces. Diffraction and morphologic data suggest that hydrogen bonds between amide groups were established along a single direction, which coincides with the preferential crystal growth direction. Spherulites prepared from both evaporation of formic acid solutions and melt crystallization have been also studied. Diffraction data indicate that hydrogen bonds are aligned along the spherulite radius. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 815–825, 2007     

Crystallization and crystal structure of poly(ester amide)s derived from L‐tartaric acid

The crystal structure and crystallization behavior of a series of poly(ester amide)s derived from L ‐tartaric acid, 1,6‐hexanediamine, and 6‐amino‐1‐hexanol were examined. The study included aregic polymers containing 5, 10, and 20% of ester groups in addition to the syndioregic polymer containing equal amounts of amide and ester groups. X‐ray diffraction data revealed that all the aregic poly(ester amide)s adopt the same crystal structure as the parent polyamide made of L ‐tartaric acid, and 1,6‐hexanediamine. In this structure, chains are slightly compressed and arranged as in the α‐form of nylon 66. Solid‐state nuclear magnetic resonance (NMR) revealed that ester groups are excluded from the crystal phase except for the case of the syndioregic polymer. Isothermal crystallization kinetics was analyzed according to the Avrami theory. Crystallization rates were found to decrease regularly with increasing contents in ester groups and with increasing crystallization temperature. Avrami exponent values close to 2 were found whereas spherulitic morphologies were observed by optical microscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 116–125, 2007     

Structural data on the packing of poly(ester amide)s derived from glycine,hexanediol, and odd‐numbered dicarboxylic acids

The crystalline structure of a series of Poly(ester amide)s derived from glycine, hexanediol, and odd‐numbered dicarboxylic acids has been studied using transmission electron microscopy and X‐ray diffraction. Polymers crystallize in an orthorhombic lattice with parameters a = 4.80 Å, b = 22.68 Å, and c in the 45–55 Å interval, depending on the number of methylenes of the chemical repeat unit. The structure of the glutaric derivative can be interpreted as a singular packing of six hydrogen‐bonded sheets. Amide and ester interactions between neighboring layers favor two different sheet arrangements that give rise to the observed superstructure. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2521–2533, 1999     

Poly(ester amide)s derived from glycine,even‐numbered diols,and dicarboxylic acids: Considerations on the packing

A new sequential poly(ester amide) derived from 1,12‐dodecanediol, sebacic acid, and glycine was synthesized and characterized. Its crystalline structure was studied with transmission electron microscopy and X‐ray diffraction. The results were compared with results for a related polymer, derived from glycine, 1,6‐hexanediol, and succinic acid, that produced a lower methylene/carbonyl ratio. The crystalline structures of both polymers corresponded to a periodic arrangement of two layers of hydrogen‐bonded molecular chains, whose polymethylene sequences mimicked the packing of polyethylene and the majority of polyesters. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1036–1045, 2001     

Poly(ester amide)s derived from L‐tartaric acid and amino alcohols. II. Aregic polymers

A series of aregic poly(ester amide)s (a‐PEAT6) with ester/amide ratios (a : b) varying from 1 : 19 to 1 : 2 were prepared with L ‐tartaric acid, 6‐aminohexanol, and 1,6 hexanediamine as the starting materials. Polycondensation in a solution of the diamine with mixtures of pentachlorophenyl‐activated di‐O‐methyl‐L ‐tartaric and 6‐aminohexyl‐di‐O‐methyl‐L ‐tartaric acids led to a‐PEAT6(a : b), with the a : b ratio determined by the composition of the feed. The newly synthesized poly(ester amide)s were characterized by elemental analysis, size exclusion chromatography, and IR and NMR spectroscopy. They had number‐average molecular weights between 25,000 and 45,000 and were highly crystalline, showing melting temperatures ranging from 100 to 230 °C and glass‐transition temperatures oscillating between 50 and 100 °C. The thermal degradation of a‐PEAT6(a : b) began above 200 °C and concluded with a final weight loss between 60 and 90% of the initial mass. The process evolved with the formation of cyclic tartarimide units and extensive main‐chain scissions. The degradation mechanism is discussed in relation to the chemical composition and microstructure of the polymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2687–2696, 2000     

Synthesis and properties of novel aromatic poly(ester amide)s derived from 1,5-bis(4-aminobenzoyloxy)naphthalene and aromatic dicarboxylic acids

A new naphthalene ring-containing bis(ester amine), 1,5-bis(4-aminobenzoyloxy)naphthalene (2), was synthesized from the condensation of 1,5-dihydroxynaphthalene with 4-nitrobenzoyl chloride followed by catalytic hydrogenation. A series of naphthalene-containing poly(ester amide)s having inherent viscosities of 0.34-0.82 dl/g were prepared by the direct phosphorylation polyamidation from bis(ester amine) 2 with various aromatic dicarboxylic acids. The poly(ester amide)s derived from terephthalic acid, 4,4′-biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-oxydibenzoic acid were semicrystalline and showed less solubility. The other polymers were amorphous and readily soluble in polar organic solvents and gave flexible and tough films via solution casting. Except for four examples, the poly(ester amide)s displayed discernible glass transitions between 190 and 227 °C by differential scanning calorimetry. These poly(ester amide)s did not show significant decomposition below 400 °C in nitrogen or air.     

Synthesis of poly(glycolic acid‐alt‐12‐aminododecanoic acid): The thermal polymerization kinetics of sodium N‐chloroacetyl‐12‐aminododecanoate

A new regular poly(ester amide) consisting of glycolic acid and 12‐aminododecanoic acid was synthesized by a thermal polycondensation method involving the formation of a metal halide salt. Polymerization could start in liquefied or solid phases, depending on the reaction temperature. The polymerization kinetics were investigated by isothermal and nonisothermal isoconversional methods. The reaction model was selected with both Coats–Redfern and isokinetic relationships. The activation energy was higher when the reaction took place mainly in the solid state. A compensation effect was found between the frequency factor and the activation energy. The thermal properties of the new polymer were studied as well as the isothermal crystallization from the melt state. Melt‐grown spherulites were studied by means of polarizing optical microscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1199–1213, 2006     

Synthesis and hydrolytic degradation of stereoregular aromatic poly(ester amide)s derived from D‐xylose

Stereoregular poly(ester amide)s (PEAs) were prepared by the polycondensation method using naturally occurring D ‐xylose and aromatic diacids as the starting materials. The polymers were characterized by elemental analysis, GPC, IR, and ¹H‐ and ¹³C NMR spectroscopies. Thermal and X‐ray diffraction studies revealed them to be mainly amorphous. The polymers are hydrophilic and their degradation studies were carried out at 37 and 80 °C in buffered salt solution at pH 8. The degradation study was monitored by mass loss, GPC, IR, and NMR spectroscopies. The hydrolytic degradation of these PEAs occurred rapidly by hydrolysis of the ester functions to a final compound, which maintained the amide functions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

New poly(ester amide)s from alkyl 2‐(carboethoxyhydroxymethyl)acrylates

The synthesis of alkyl 2‐(carboethoxyhydroxymethyl)acrylates via the Bayllis‐Hillmann reaction pathway is described. These compounds are found to be poor monomers when involved in free radical polymerizations but present an extremely high reactivity upon Michael addition with primary amines leading to a simple, mild and efficient route to the preparation of new multifunctional heterocycles and polymers with potential applications in biodegradable coatings. Real‐time NMR spectroscopy permitted monitoring the extent of the reaction sequence and determining the conversion profile of reactants and Michael adduct intermediate. Poly(ester amide)s derived from diamine and hexane bis‐2‐(carboethoxyhydroxymethyl)acrylate were synthesized at room temperature by means of a very efficient Michael addition/cyclization polymerization. These polymers display excellent adhesion to metal, glass, and paper substrates and interesting hydrolytic susceptibility. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3182–3192, 2008     

Synthesis and characterization of a family of biodegradable poly(ester amide)s derived from glycine

A series of aliphatic poly(ester amide)s derived from 1,6-hexanediol, glycine, and diacids with a variable number of methylenes (from 2 to 8) have been synthesized and characterized. Infrared spectroscopy shows that the studied polymers present a unique kind of hydrogen bond that is established between their amide groups. Thermal properties as melting, glass transition, and decomposition temperatures are reported. The data indicate that all the polymers are highly crystalline. Thus, different kinds of spherulites (positive and/or negative) were obtained depending on the preparation conditions and on the polymer samples. Moreover, all the polymers crystallized from dilute diol solutions as ribbonlike crystals where a regular folding habit and a single hydrogen bond direction could be deduced. A test of enzymatic hydrolysis was employed to assess the potential biodegradability of these polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1271–1282, 1998     

Synthesis and characterization of functionalized water soluble cationic poly(ester amide)s

A new family of positively charged, water soluble and functional amino acid‐based poly(ester amide)s ( Arg‐AG PEA ) consisting of four building blocks (L ‐Arginine, DL ‐2‐Allylglycine, oligoethylene glycol, and aliphatic diacid) were synthesized by the solution copolycondensation. Functional pendant carbon–carbon double bonds located in the DL ‐2‐allylglycine unit were incorporated into these Arg‐AG PEAs, and the double bond contents could be adjusted by tuning the feed ratio of L ‐arginine to DL ‐2‐allylglycine monomers. Chemical structures of this new functional Arg‐AG PEA family were confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectra. The thermal property of these polymers was investigated; increasing the methylene chain in both the amino acid and diacid segments resulted in a reduction in the polymer glass‐transition temperature. All these cationic Arg‐AG PEAs had good solubility in water and polar organic solvents. The cytotoxity of Arg‐AG PEAs was evaluated by 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay. These preliminary MTT results indicated that Arg‐AG PEAs were nontoxic to bovine aortic endothelial cells (BAECs). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3758–3766, 2010     

Amino acid‐based bioanalogous polymers. Synthesis,and study of regular poly(ester amide)s based on bis(α‐amino acid) α,ω‐alkylene diesters,and aliphatic dicarboxylic acids

The purpose of this research was to synthesize new regular poly(ester amide)s (PEAs) consisting of nontoxic building blocks like hydrophobic α‐amino acids, α,ω‐diols, and aliphatic dicarboxylic acids, and to examine the effects of the structure of these building block components on some physico‐chemical and biochemical properties of the polymers. PEAs were prepared by solution polycondensation of di‐p‐toluenesulfonic acid salts of bis‐(α‐amino acid) α,ω‐alkylene diesters and di‐p‐nitrophenyl esters of diacids. Optimal conditions of this reaction have been studied. High molecular weight PEAs (M_w = 24,000–167,000) with narrow polydispersity (M_w/M_n = 1.20–1.81) were prepared under the optimal reaction conditions and exhibited excellent film‐forming properties. PEAs obtained are mostly amorphous materials with T_g from 11 to 59°C. α‐Chymotrypsin catalyzed in vitro hydrolysis of these new PEA substrates was studied to assess the effect of the building blocks of these new polymers on their biodegradation properties. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 391–407, 1999     

New amino acid based biodegradable poly(ester amide)s via bis-azlactone chemistry

Abstract

Three new classes of the amino acid based biodegradable (AABB) polymers were synthesized via step growth polymerization of bis-azlactones and amino acid based diamine-diesters with activated fatty diester and alkylenediamine: a) poly(ester amide)s (PEAs) were obtained by polymerization of bis-azlactones with diamine-diesters, b) hydrophobically modified co-poly(ester amide)s (co-PEAs) were synthesized by copolymerization of activated fatty diacid diester and bis-azlactones with diamine-diesters, and c) poly(ester amide-co-amide)s (PEA-co-PAs) were obtained by copolymerization of alkylene diamine and diamine-diesters with bis-azlactones. The new poly(ester amide)s showed relatively low-molecular-weights (M_w within 2,800–19,600?Da, GPC in DMF), whereas the new co-poly(ester amide)s and poly(ester amide-co-amide)s exhibited high-molecular-weights (M_w within 40–100?kDa) leading to good mechanical properties. Incorporation of the bis-azlactone fragments into the poly(ester amide)s backbone increased hydrophobicity and thermal stability, whereas incorporation of diamine-diester units into the backbone of the bis-azlactone based polyamides rendered them biodegradable. Synthesized AABB polymers are potential candidates for constructing resorbable surgical and pharmaceutical devices.     

Soluble, thermally stable poly(ester amide)s derived from terephthalic acid bis(carboxydiphenyl methyl)ester and different diamines

Terephthalic acid bis(carboxydiphenyl methyl)ester (TBE) as a new monomer for the preparation of polyamides was synthesized through the nucleophilic substitution reaction of benzilic acid with terephthaloyl chloride. This diester-diacid (TBE) was characterized using conventional spectroscopic methods. Polycondensation reactions of TBE with different aromatic and semi-aromatic diamines via Yamazaki method resulted different poly(ester amide)s. All the polymers were characterized and their physical and thermal properties were studied.     

Fluorinated polyamides and poly(amide imide)s based on 1,4‐bis(4‐amino‐2‐trifluromethylphenoxy)benzene,aromatic dicarboxylic acids,and various monotrimellitimides and bistrimellitimides: Syntheses and properties

A CF₃‐containing diamine, 1,4‐bis(4‐amino‐2‐trifluromethylphenoxy) benzene ( I ), was prepared from hydroquinone and 2‐chloro‐5‐nitrobenzotrifluoride. Imide‐containing diacids ( V _a–h and VI _a,b ) were prepared through the condensation reaction of amino acids, aromatic diamines, and trimellitic anhydride. Then, a series of soluble fluorinated polyamides ( VII _a–h ) and poly(amide imide)s ( VIII _a–h and X _a,b ) were synthesized from I with various aromatic diacids ( II _a–h ) and imide‐containing diacids ( V _a–h and VI _a,b ) via direct polycondensation with triphenyl phosphate and pyridine. The polyamides and poly(amide imide)s had inherent viscosities of 1.00–1.70 and 0.79–1.34 dL/g, respectively. All the synthesized polymers showed excellent solubility in amide‐type solvents such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, and N‐dimethylformamide and afforded transparent and tough films via solvent casting. Polymer films of VII _a–h , VIII _a–h , and X _a,b had tensile strengths of 91–113 MPa, elongations to break of 8–40%, and initial moduli of 2.1–2.8 GPa. The glass‐transition temperatures of the polyamides and poly(amide imide)s were 254–276 and 255–292 °C, respectively, and the imide‐containing poly(amide imide)s had better thermal stability than the polyamides. The polyamides showed higher transparency and were much lighter in color than the poly(amide imide)s, and their cutoff wave numbers were below 400 nm. In comparison with isomeric IX _{c – h} , poly(amide imide)s VIII _c–h exhibited less coloring and showed lower yellowness indices. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3116–3129, 2004     

Synthesis of star‐shaped poly(D,L‐lactic acid‐alt‐glycolic acid)‐b‐poly(L‐lactic acid) with the poly(D,L‐lactic acid‐alt‐glycolic acid) macroinitiator and stannous octoate catalyst

Two types of three‐arm and four‐arm, star‐shaped poly(D,L ‐lactic acid‐alt‐glycolic acid)‐b‐poly(L ‐lactic acid) (D,L ‐PLGA50‐b‐PLLA) were successfully synthesized via the sequential ring‐opening polymerization of D,L ‐3‐methylglycolide (MG) and L ‐lactide (L ‐LA) with a multifunctional initiator, such as trimethylolpropane and pentaerythritol, and stannous octoate (SnOct₂) as a catalyst. Star‐shaped, hydroxy‐terminated poly(D,L ‐lactic acid‐alt‐glycolic acid) (D,L ‐PLGA50) obtained from the polymerization of MG was used as a macroinitiator to initiate the block polymerization of L ‐LA with the SnOct₂ catalyst in bulk at 130 °C. For the polymerization of L ‐LA with the three‐arm, star‐shaped D,L ‐PLGA50 macroinitiator (number‐average molecular weight = 6800) and the SnOct₂ catalyst, the molecular weight of the resulting D,L ‐PLGA50‐b‐PLLA polymer linearly increased from 12,600 to 27,400 with the increasing molar ratio (1:1 to 3:1) of L ‐LA to MG, and the molecular weight distribution was rather narrow (weight‐average molecular weight/number‐average molecular weight = 1.09–1.15). The ¹H NMR spectrum of the D,L ‐PLGA50‐b‐PLLA block copolymer showed that the molecular weight and unit composition of the block copolymer were controlled by the molar ratio of L ‐LA to the macroinitiator. The ¹³C NMR spectrum of the block copolymer clearly showed its diblock structures, that is, D,L ‐PLGA50 as the first block and poly(L ‐lactic acid) as the second block. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 409–415, 2002     

聚酯-酰胺的水解降解行为

研究了各种条件下聚酯-酰胺的水解降解行为及其与结构之间的关系。结果表明：酯键含量越高,质量损失就越快。聚合物的降解受酸、碱催化。根据SEM观察提出了可能发生的降解机理：表面腐蚀、非晶区腐蚀、晶区破坏到全部降解。     

LC polyimides. XXXVI. Poly(ester imide)s derived from N,N′‐Bis(4‐hydroxyphenyl)biphenyl‐3,3′,4,4′‐tetracarboxylic diimide and aliphatic dicarboxylic acids

A new mesogenic monomer was prepared from biphenyl‐3,3′,4,4′‐tetracarboxylic dianhydride and 4‐aminophenol followed by the acylation of OH groups with propionic anhydride. This diphenol propionate was polycondensed by transesterification with decane‐1,10‐dicarboxylic acid, dodecane‐1,12‐dicarboxylic acid, and eicosane‐1,20‐dicarboxylic acid or with equimolar mixtures of two dicarboxylic acids. The resulting poly(ester imide)s were characterized by elemental analyses, ¹H NMR spectra, inherent viscosities, DSC measurements, optical microscopy, and X‐ray measurements with synchrotron radiation at variable temperatures. An enantiotropic smectic A phase in the molten state and a crystalline smectic E (or H) phase in the solid state were found in all cases. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3019–3027, 2000     

Synthesis and investigation of the effect of nematic phases on the glass‐transition behavior of novel cycloaliphatic liquid‐crystalline poly(ester amide)s

We designed and developed novel cycloaliphatic liquid‐crystalline (LC) poly(ester amide)s to investigate the effects of nematic LC phases and hydrogen‐bonding interactions on the glass‐transition behavior. Three series of poly(ester amide)s based on commercially important poly(1,4‐cyclohexanedimethylene terephthalate) were synthesized with two new cycloaliphatic diamines {3,8‐bis(aminomethyl)‐tricyclo [5.2.1.0.(2,6)]decane (tricyclic) and 1,3‐cyclohexane bismethylene amine (monocyclic)} and a linear counterpart (1,6‐hexamethylene diamine). The compositions of the ester/amide units in the copolymers were varied up to 50% by the adjustment of the amounts of the diol and diamine in the feed. The structures of the polymers were confirmed with NMR and Fourier transform infrared, and their inherent viscosities were measured at 30 °C with an Ubbelohde viscometer. Thermal analysis revealed that the poly(ester amide)s having less than 25 mol % amide linkages were thermotropic and LC, and threadlike nematic phases were observed under a polarizing microscope. The introduction of nematic, LC phases drastically affected the glass‐transition temperatures of the copolymers, and a plot of the composition versus the glass‐transition temperature passed through a maximum for lower amide incorporation, regardless of the structural differences of the amide units (cyclic or linear). This nonlinear Flory–Fox trend was correlated to the cooperative effect of the strong alignment of polymer chains in the nematic phases and intermolecular packing induced by the hydrogen bonding in the poly(ester amide)s. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5557–5571, 2006     

Synthesis and characterization of poly(aryl amide imide)s derived from diphenyltrimellitic anhydride

The synthesis and characterization of a series of novel poly(aryl amide imide)s based on diphenyltrimellitic anhydride are described. The poly(aryl amide imide)s, having inherent viscosities of 0.39–1.43 dL/g in N-methyl-2-pyrrolidinone at 30°C, were prepared by polymerization with aromatic diamines in N,N-dimethylacetamide and subsequent chemical imidization. All the polymers were amorphous, readily soluble in aprotic polar solvents such as DMAC, NMP, dimethylsulfoxide, N,N-dimethylformamide, and m-cresol, and could be cast to form flexible and tough films. The glass transition temperatures were in the range of 284–366°C, and the temperatures for 5% weight loss in nitrogen were above 468°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4541–4545, 1999