Diacid Monomer Research Articles

ROS-responsive electrospun poly(amide thioketal) mats for wound dressing applications

Excessive levels of reactive oxygen species (ROS) are usually associated with the inflammatory response during the wound healing process. Therefore, strategies that can locally control the adverse effects of excessive formation of ROS may lead to improved healing times. In this work, ROS-responsive scavenging materials were developed using a degradable poly(amide thioketal) (PATK) polymer. This PATK polymer was prepared using a thioketal (TK) diacid monomer which gives the polymer the ability to be degraded by ROS. This PATK polymer was used to prepare electrospun mats by blending it with the biocompatible poly(ε-caprolactone) (PCL). The developed mats showed good degradability when exposed to an oxidative environment and can also be degraded by a photo-mediated mechanism. Cytotoxicity tests performed in vitro on a fibroblast cell line showed that the mats had no adverse effects on the cells, confirming the potential of these systems for biomedical applications. In addition, the antioxidant capacity of the membranes was also found to be good, which could be relevant for wound dressing applications.

Ether-type co-solvents of excellence for aqueous base-free Pt-catalyzed oxidation of concentrated 5-(hydroxymethyl)furfural to 2,5-furandicarboxylic acid

The biomass-derived 5-(hydroxymethyl)furfural (5-HMF) is readily converted in water to 2,5-furandicarboxyl acid (FDCA) that is well known as a renewable diacid monomer. However, the limited solubility of FDCA in water posed serious challenges to process development. Herein, the base-free Pt-catalyzed oxidation of 5-HMF was explored in aqueous binary solvent systems containing organic co-solvents such as dimethyl sulfoxide, N,N-dimethylformamide, gamma-valerolactone, dioxane, diethylene glycol dimethyl ether, and 1,2-dimethoxyethane (DME). The FDCA solubility and 5-HMF oxidation performance were investigated in co-solvent/H2O systems with different co-solvent fractions. When correlated with the solvatochromic parameters of co-solvents, the FDCA yield appeared to be in harmony with their polarizability and hydrogen bonding acceptance ability. Thus, infrared spectra were collected with three systems such as co-solvent/H2O, 5-HMF in co-solvent, and 5-HMF in co-solvent/H2O. The employed co-solvent was found to have different abilities to interact with the O–H and C=O moieties of 5-HMF via H-bonding and dipole-induced dipole attraction (related with the polarizability), respectively. Consequently, a high FDCA yield was achieved using three ether-type co-solvents in which these interactions are relatively weak. In a continuous-flow pattern for the base-free oxidation of 3 wt% 5-HMF solution, a FDCA yield of >98 % was achieved with 60 wt% DME/H2O under the optimized conditions.

Effect of CH2 run length on the crystallization kinetics of sustainable long-spaced aliphatic polyesters

We have studied the isothermal overall crystallization rates and linear growth rates of four symmetric long-spaced aliphatic polyesters (LSAPEs) with 12, 18, 32, or 48 carbons in both the diol and the diacid monomers. With increasing crystallization temperature (Tc) these LSAPEs display discrete rate minima in a number and depth that depend on the length of the methylene spacer between esters. Two rate minima are observed for PE-48,48 and for PE-32,32; one for PE-18,18 and none for PE-12,12. The rate minima are not associated with a change in the mechanism of nucleation and growth or with a change in crystal packing, but occur at Tc where the crystal thickness transitions from a non-integer to a quantized integer number of monomer units. We explain such rate minima based on the self-poisoning feature used earlier to explain similar findings in n-alkanes and other types of precision polyethylene-like systems. In LSAPEs, metastable non-integer crystals attach to the growth front of stable integer crystals retarding their growth until the non-integer segments thicken to complete the layer. Lack of rate minima in the shortest-spaced symmetric polyester is explained by a small difference in lamellar thickness between non-integer and integer layered crystals which favors the formation of integer crystals at any Tc.

Synthesis and Properties of Polyamide 6 Random Copolymers Containing an Aromatic Imide Structure.

In order to adjust the properties of polyamide 6 (PA6) and expand its application, a new strategy of introducing an aromatic imide structure into the PA6 chain through the random copolymerization method is reported. The diimide diacid monomer was first synthesized by the dehydration and cyclization of pyromellitic dianhydride and 6-aminocaproic acid before it reacted with 1,6-hexamethylene diamine to form poly(amide imide) (PAI) salt, and finally synthesized PA6/PAI random copolymers containing an aromatic imide structure by the random copolymerization of ε-caprolactam and PAI salt. The introduction of an aromatic imide structural unit into the PA6 chain could have a great influence on its properties. As the content of PAI increases, the crystallinity (Xc) and melting temperature (Tm) of the PA6/PAI random copolymer gradually decrease, but its glass transition temperature (Tg) increases obviously. When the PAI content is 20 wt%, the copolymer PA6/PAI-20 has the best comprehensive performance and not only has high thermal stabilities but also excellent mechanical properties (high strength, high modulus, and good toughness) and dielectric properties (low dielectric constant and dielectric loss). Moreover, these properties are significantly superior to those of PA6. Such high-performance PA6 random copolymers can provide great promise for the wider applications of PA6 materials.

Molecular design of soluble poly(amide-imide) with high char yield for flame retardant epoxy resin

Abstract In this study, a noncoplanar diimide diacid monomer (DIDA) was synthesized by direct condensation of trimellitic anhydride (TMA) with m-tolidine. The noncoplanar unit was incorporated into poly(amide-imide)s (PAIs) main chain by Yamazaki-Higashi phosphorylation of DIDA with various aromatic diamines. Encouragingly, all of the PAIs show good solubility in some common solvents such as N,N-Dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone (NMP), and m-cresol. In addition, the soluble PAIs show good optical transmittances of beyond 85 % at 500 nm due to the decreased crystallization ability. On the other hand, PAIs possess good mechanical properties with tensile strengths of 72–90 MPa and tensile moduli beyond 2 GPa. Meanwhile, the designed PAIs also exhibit excellent thermal properties: their glass transition temperatures (T g) range from 278 to 314 °C, initial decomposition temperatures (5 % weight loss temperatures, T 5wt%) are beyond 470 °C, coefficients of thermal expansion (CTE) are below 10 ppm/°C. The excellent mechanical and thermal properties are due to the strengthened hydrogen bonding interaction among the amide groups. Therefore, it is believed that incorporating noncoplanar unit and amide group into the polymer main chain at the same time can simultaneously improve processability, optical transparency, mechanical and thermal properties. Furthermore, it is worth noting that the char of PAI at 800 °C is as high as 72.5 %, which is one of the highest known values. When PAI was incorporated into epoxy resin, the blend passed UL94 V-0 rating due to the high charring capability of PAI.

Synthesis and properties of biodegradable aliphatic–aromatic polyesters derived from 4‐hydroxybenzaldehyde

AbstractA novel biphenyl monomer, diethyl 6,6′‐dimethoxy‐[1,1′‐bipheny]‐3,3′‐dicarboxylate (DDBD), was synthesized from 4‐hydroxybenzaldehyde, a phenolic compound derived from lignin. A series of polyesters were prepared by polycondensation of the biphenyl monomer with hydroquinone bis(2‐hydroxyethyl) ether and aliphatic diacids via a two‐step melt polycondensation method. It was shown that the properties of the polyesters can be tuned by varying the length and the structure of the spacer in the aliphatic diacid monomers. Structure–property relations for these materials were investigated by Fourier‐transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. GPC analysis showed that the weight‐average molecular weight (Mw) of the samples varied from 4.2–5.0 × 104 g/mol, while thermal analysis yielded Tg values of 51–120°C, and 5% decomposition temperatures (Td,5%) of 327–389°C. All the samples exhibited a high yield strength (56–87 MPa). After 30 weeks of degradation in soil, the copolyesters had mass losses of up to 4.4%, and an investigation of the ecotoxicity of the copolyesters with Eisenia fetida yielded a survival rate of over 80% after 14 days for the different copolyesters, suggesting low toxicity in the environment. Overall, these copolyesters have good properties and would be suitable to replace petroleum‐based commercial poly(ethylene terephthalate) packaging materials.

Sulfonated Polybenzimidazole as a PEM in a Microbial Fuel Cell: An Efficient Strategy for Green Energy Generation and Wastewater Cleaning

A microbial fuel cell (MFC) is a bioelectrochemical system that has a dual application: producing renewable energy and simultaneously purifying dirty water. However, low power density and high installation cost are the major limitations. To overcome these problems and to replace the highly expensive Nafion which is used as a proton exchange membrane (PEM) in MFCs, here, in this study, a high-molecular weight sulfonated oxybispolybenzimidazole (MSOPBI) membrane has been made from the newly synthesized sulfonated diacid monomer in a readily executable synthetic path and cost-effective manner, and finally, the MSOPBI membrane has been tested in a dual-chamber MFC. The newly synthesized MSOPBI membrane displayed less water uptake, moderate ion exchange capacity (IEC) and proton conductivity in the hydrated state, low dimensional swelling, and phase-separated morphology with enhanced mechanical strength due to the more compact and rigid structure of the membrane owing to the crosslinking between the sulfonic functional group and imidazole group. It demonstrated a higher MFC performance because of the various favorable factors including morphological features. The MFC operation in the presence of the MSOPBI membrane when compared with that with Nafion showed an open-circuit voltage (OCV) of 345 mV, a power density of 280 mW/m2, and a current density of 2.2 mA/m2 from the polarization curves with a relatively less voltage drop. Compared to Nafion, MSOPBI showed an increase in power density by 47%. Electrochemical analysis (OCV, cyclic voltammetry (CV), linear sweep voltammetry (LSV), Tafel curves) depicted the increased bioelectrochemical activity during the MFC operation in the presence of MSOPBI owing to its compositional and low-swelling characteristic functionality that impacted the decreased resistances and system losses toward enhanced power/energy output compared to that with the Nafion membrane. All these data together proved the effectiveness of the newly synthesized MSOPBI membrane for use in MFCs for the production of green energy and cleaning wastewater.

Approach for the Low Carbon Footprint of Biodegradable Plastic PBAT: Complete Recovery of Its Every Monomer via High-Efficiency Hydrolysis and Separation

Biodegradable plastics are considered one of the solutions to solve the environmental pollution caused by plastic waste. However, on easy-to-collect occasions, recovery of biodegradable plastics is a preferable option rather than biodegradation, since it can fully utilize carbon resources and reduce carbon emissions. Herein, efficient and eco-friendly recycling of widely used biodegradable plastic, polybutylene adipate terephthalate (PBAT), was demonstrated by alkaline hydrolysis in the solution of ethanol and H2O. The degradation ratio of PBAT was achieved above 99% at 80 °C for 50 min. Diacid salts were self-precipitated out from the reaction solution, followed by acidification to obtain diacid monomers. The reaction solution after filtrating away the diacid salts can be recycled several times without sacrificing the degradation ratio of PBAT, while 1,4-butanediol monomer can be further recovered by the two-step mild distillation at 80 °C. The carbon emission of the whole recycling process was evaluated, and it was only half of that of the biodegradation. The work provides new insight into the recycling of biodegradable plastics.

Structure and properties of a flame retardant ternary vitrimer regulated by cyclic and long-chain dicarboxylic acids

A vitrimer is a kind of polymer with a dynamic network that has received extensive attention. An epoxy monomer containing a phosphonate group (E) has been used to endow a vitrimer with flame retardancy. 1, 4-cyclohexanedicarboxylic acid (CA) was used as a diacid monomer. Dodecanedioic acid (DA) containing a long aliphatic chain was used as a third monomer to regulate the structure and properties of the vitrimer. The flame retardant properties were investigated using UL-94 vertical combustion, limiting oxygen index (LOI). The results showed that the E/1C/2D vitrimer containing CA/DA (mole ratio1:2) displays a UL-94 V-0 rating and a LOI value of 31%. Furthermore, the vitrimers possesse excellent recyclable and multiple shape memory performance. The E/1C/2D vitrimer may be structurally modified rapidly via transesterification reaction between an ester and neighboring β‑hydroxy groups at 170 °C. The recycling efficiency is nearly 100%. The tensile strength and modulus of E/1C/2D may be as high as 97 MPa and 2173 MPa, respectively. The tensile strength is not significantly decreased as a consequence of two reformation events. A simple method for the regulation of the flame retardancy and mechanical properties of vitrimers has been demonstrated.

Overcoming the low reactivity of biobased, secondary diols in polyester synthesis

Shifting away from fossil- to biobased feedstocks is an important step towards a more sustainable materials sector. Isosorbide is a rigid, glucose-derived secondary diol, which has been shown to impart favourable material properties, but its low reactivity has hampered its use in polyester synthesis. Here we report a simple, yet innovative, synthesis strategy to overcome the inherently low reactivity of secondary diols in polyester synthesis. It enables the synthesis of fully biobased polyesters from secondary diols, such as poly(isosorbide succinate), with very high molecular weights (Mn up to 42.8 kg/mol). The addition of an aryl alcohol to diol and diacid monomers was found to lead to the in-situ formation of reactive aryl esters during esterification, which facilitated chain growth during polycondensation to obtain high molecular weight polyesters. This synthesis method is broadly applicable for aliphatic polyesters based on isosorbide and isomannide and could be an important step towards the more general commercial adaption of fully biobased, rigid polyesters.

Synthesis and characterizations of high oil length alkyd resin with dehydrated castor oil and acrylic pimaric acid

Alkyd resin (AR) has been widely used for paint applications due to its good adhesion, flexibility and durability. They were polymerized from three different kinds of monomers: polyols, aromatic diacids and vegetable oils or fatty acids. In this work, acrylic pimaric acid (APA) was evaluated as an bio-based substitute for the aromatic diacid monomer including phthalic anhydride (PA) in the synthesis of high oil length (65 % oil by weight) alkyd resins (HOARs). APA was synthesized from the Diels-Alder reaction between rosin acid (RA) and acrylic acid (AA). The resins were characterized in terms of gloss, pencil hardness, impact strength, alkali resistance and thermal stability. APA can be incorporated when the polyesterification reaction is performed in two-stages, that is, it is only added with ethylene glycol (EG) in the first stage polyesterification reaction, because the reactivity of APA is weaker than that of PA. The structure of the prepared HOARs was investigated by FTIR and 1H NMR spectroscopy. The results show that HOAR having 9 % APA has good gloss, pencil hardness and impact strength and excellent alkaline resistance. The price is decreased by about 20 % compared to conventional AR and it can be widely used as a binder in the field of the protective paint.

Synthesis of Aliphatic Polyanhydrides with Controllable and Reproducible Molecular Weight.

Polyanhydrides have been synthesized for decades by melt-polycondensation of diacid monomers and 5 to >10 times mole excess acetic anhydride to diacid monomers to form polymers with a polydispersity ranging from 2.5 to 6 and low reproducibility. Hydrophobic segments in polyanhydrides are beneficial to hinder the characteristic hydrolytic cleavage of an anhydride bond that provides stable polyanhydrides at room temperature. The objective of this work is to synthesize aliphatic polyanhydrides with various hydrophobic segments, controllable and reproducible molecular weight, and low polydispersity that are essential for potential use as drug carriers. A series of polyanhydrides of suberic, azelaic, sebacic, and dodecanedioic acids with controlled molecular weight, reduced polydispersity, and standard deviation of molecular weights, have been synthesized. All synthesized polyanhydrides were thoroughly characterized by NMR, Fourier transform infrared spectroscopy, and gel permeation chromatography. Molecular weights of the synthesized polyanhydrides are highly controllable, depending on the degree of activation of the dicarboxylic acid monomers, i.e., the amount of acetic anhydride used during synthesis. Polyanhydrides have been synthesized in triplicate by melt-polycondensation, using various mole ratios of acetic anhydride to diacids. The standard deviation of the molecular weights of the polyanhydrides is minute when using 1 equivalent of acetic anhydride during the activation of dicarboxylic acids, whereas if excess acetic anhydride is used, the standard deviation is very high. The effect of safe and natural inorganic catalysts, Calcium oxide, Zinc oxide, and Calcium carbonate on polymerization is also studied. As-synthesized poly(sebacic acid) can offer convenience to use in controlled drug delivery applications. In vitro drug release study using Temozolamide (TMZ), a medication used to treat brain tumors such as glioblastoma and anaplastic astrocytoma, shows 14% TMZ release after the first hour and 70% release over one day from the poly(sebacic acid) wafers.

Synthesis and Characterization of Bio-Based Poly(amide imide)s Derived from 11-Aminoundecanoic Acid and 1,10-Diaminodecane

Three diimide diacid (DIDA) monomers possessing different rigid groups (phenyl, biphenyl and diphenyl ether group) between two imide rings were prepared through the dehydration cyclization reaction of 11-aminoundecanoic acid and aromatic dianhydride. These DIDA monomers were polymerized with 1,10-diaminodecane to produce bio-based poly(amide imide)s (PAIs) by the ecofriendly and low-cost two-step polymerization method. All the PAIs have high thermal stabilities, and their initial thermal decomposition temperatures are above 400 °C at 5% weight loss. When the rigid group between two imide rings is changed from phenyl to diphenyl ether group, the glass transition temperature of PAI shows a decreasing trend from 54.7 °C to 42.4 °C, the tensile strength also reduces from 62.4 MPa to 49.5 MPa, but elongation at break increases from 3.7% to 6.8%. Moreover, the PAI with phenyl group between two imide rings is a semicrystalline polymer, while the PAI with biphenyl or diphenyl ether group is an amorphous polymer. It is a viable way to regulate the properties of PAIs by changing the structure of rigid group between two imide rings. Such bio-based PAIs with high thermal stabilities, low glass transition temperatures and good mechanical strength will provide great promise for their wider applications.

Soluble and transparent poly(amide-imide)s with ultra-low coefficients of thermal expansion

Transparent and soluble poly(amide-imide)s (PAIs) with high dimensional stability were synthesized from the monomer consisting of a dibenzodioxin skeleton. The diimide-dicarboxylic acid monomers were synthesized from dibenzo-dioxin tricarboxylic acid anhydride and trimellitic anhydride with 2,2′-bis(trifluoromethyl)benzidine, and a series of PAIs were prepared from the polymerization of the diacid monomers with 2,2′-bis(trifluoromethyl)benzidine. All the polymers were soluble in polar organic solvents and can be solution-cast into nearly colorless and flexible freestanding films. The obtained PAI films possessed high T d5 value (469–481 °C in N 2 ) and high transparency (∼88% transmittance at 550 nm). Interestingly, PAIs prepared in this study exhibited high thermo-dimensional stability with low CTE values as low as 1.3 ppm/ ° C. • Soluble poly(amide-imide)s are synthesized from the rigid ladder-type monomer. • The freestanding polymer films show low CTE values around 2 ppm/ ° C. • The amorphous polymers having dibenzo-dioxin units have high optical transparency.

Synthesis and characterization of organosoluble thermally stable polyamides containing spacer methylene linkage and bulky tetraphenylfuran moiety

Thermally stable and organo-soluble polyamides synthesized by polycondensation reaction of diacid monomer, 2, 5-bis (4-carboxymethylene phenyl) 3, 4-diphenyl furan (BCMPDF) with various commercially available aromatic diamines such as 4,4′-Oxydianiline, 4,4′-methylenedianiline, 4,4'-sulphonyldianiline, 4,4'-Diaminobenzophenone and 4,4'-(hexafluoroisopropylidene)dianiline by using Yamazaki’s direct phosphorylation method. A 2, 5-bis (4-carboxymethylene phenyl) 3, 4-diphenyl furan (BCMPDF) as a new compound containing methylene linkage and bulky moiety of tetraphenylfuran was successfully prepared by a four step reaction. The resulted polymers show excellent thermal stability, good solubility in aprotic polar solvent and inherent viscosities between 0.50 and 0.58 dl/g. Wide angle X-ray diffraction of all these PAs show amorphous nature. Polyamides showed glass-transition temperatures in the range of 169–213 °C indicate that polymers are easily processable. Thermogravimetric analysis of the polyamides indicated a 10% weight loss (T10) in the temperature range of 449–510 °C and char yields at 900 °C under nitrogen atmosphere in the range of 49–58% depending on the diamine monomer used for the synthesis polyamides. The structure -property correlation among these polyamides were discussed. The limiting oxygen indexes of all polyamides are more than 37.1, thus such type polymers of can act as flame retardant materials. These polyamides will be useful for high performance applications.

Furfural-Based Modification of PET for UV-Blocking Copolymers with Decreased Oxygen Permeability

2,2′-Bifuran-5,5′-dicarboxylic acid (BFDCA), a highly promising biobased diacid monomer, was used to modify poly(ethylene terephthalate) (PET) to obtain copolyesters with increased biocarbon content and improved properties compared with PET. Antimony-catalyzed copolymerization of the bifuran and terephthalate 2-hydroxyethyl esters was used to afford the PETBF copolymers. When compared against PET, these random copolymers with 5, 10, or 15 mol % of the bifuran comonomer in the feed (relative to the total amount of the starting esters) showed a slightly elevated glass transition range, higher tensile moduli, enhanced oxygen gas barrier properties, and superior UV blocking while maintaining good transparency otherwise. Based on our results, PETBF copolyesters seem to have promise as materials with enhanced properties that are desirable in advanced packaging applications.

High‐Performance BioNylons from Itaconic and Amino Acids with Pepsin Degradability

AbstractThe use of renewable feedstock for polymers has led to poor thermomechanical properties with high production costs. Herein, the production of novel chiral dicarboxylic acids derived from renewable itaconic and amino acids (d‐ or l‐leucine) is reported. In this study, rigid chiral heterocyclic dicarboxylic acid monomers are obtained with high purity from itaconic acid‐derived dimethyl itaconate as a starting material. Chirally interactive polyamides are prepared via melt polycondensation of hexamethylenediamine with heterocyclic diacid monomers. Further studies are conducted on d‐ or l‐leucine‐derived polyamides with homochirality that are fully amorphous. In contrast, the crystallization degree of the composite of d‐leucine‐derived polymer chains with l‐leucine‐derived chains increases to 36%, presumably due to enhanced interaction between polymer chains with different chiralities. The chirally‐interacting composite shows a glass transition temperature, Tg, of approximately 117 °C and a melting temperature, Tm, of approximately 213 °C, which are higher than those of conventional polyamides such as polyamide 11 (Tg of approximately 57 °C). The composite also shows high Young's moduli, E, and mechanical strengths σ, ranging from 2.2–3.8 GPa and 86–108 MPa, respectively. In addition, the polyamides show degradability with a digestive enzyme, pepsin.

Synthesis and characterization of aliphatic aromatic polyamides containing pyridine and methylene spacer group in polymer backbone

Thermally stable and organo-soluble polyamides synthesized by polycondensation reaction of novel diacid monomer, 2,2'-[pyridine-2,6-diylbis(oxy-4,1-phenylene)]diacetic acid with various commercially available aromatic diamines such as Pyridine-2,6-diamine, 4-(4-aminophenylsulfonyl) benzenamine, 4-(4-aminobenzyl)benzenamine and 4-(4-aminophenoxy)benzenamine by using Yamazaki’s direct phosphorylation method. A 2,2'-[pyridine-2,6-diylbis(oxy-4,1-phenylene)]diacetic acid as a new compound containing methylene linkage and the heteroaromatic unit was successfully prepared by a displacement reaction. The resulted polymers show excellent thermal stability, good solubility in an aprotic polar solvent and inherent viscosities between 0.65 and 0.82 dL g−1. X-ray diffraction of all these polyamides shows amorphous nature. Polyamides showed glass-transition temperatures in the range of 193–199 °C indicates that polymers are easily processable. Thermogravimetric analysis of the polyamides indicated a 10% weight loss (T 10%) in the temperature range of 460–518 °C and char yields at 800 °C under nitrogen atmosphere in the range of 50–65% depending on the diamine monomer used for the synthesis polyamides. The structure-property correlation among these polyamides were discussed. The limiting oxygen indexes of all polyamides are more than 37.87, thus such type polymers of can act as flame retardant materials. These polyamides will be useful for high-performance applications.

The Thermal Properties and Degradability of Chiral Polyester-Imides Based on Several l/d-Amino Acids.

Eight kinds of chiral diacid monomers were prepared with amino acids with different side groups or configurations. Polyester-imides (PEIs) were synthesized from these diacid monomers and diphenol monomers through polycondensation reaction, and the performances and properties were compared with the chiral polyamide-imides (PAIs) previously synthesized by our work group. Their thermal properties were analyzed by thermo gravimetric analysis (TGA) and dynamic thermomechanical analysis (DMA), and it was found that the glass transition temperature (Tg) of PEI was mainly affected by the volume of side groups. Their degradability was studied through buffer degradation experiments, and the changes in their water contact angle, molecular weight, structure and appearance during the degradation process were characterized by contact angle tester, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). With degradation, the hydrophilicity of PEI was improved, and when amino acids with larger side groups or D configuration were introduced into the backbone of PEI, the degradability decreased.

Synthesis and Characterization of New Organosoluble and Thermally Stable Aromatic Polyamides Containing Flexible Ether, Ketone, and Methylene Linkages

AbstractA new aromatic diacid monomer, namely, 1,4‐phenylene‐bis‐[[4′‐(4″‐carboxy methylene) phenoxy phenyl] methanone] (PBCPPM) is successfully synthesized and characterized by physical constant, FT‐IR, NMR (1H and 13C) spectroscopy, and mass spectrometry. Synthesis of new series of polyamides with high thermal stability and improved solubility are performed by Yamazaki's direct phosphorylative polycondensation method from new PBCPPM with different aromatic diamines. The inherent viscosity of these polyamides is in the range 0.47–0.81 dL g−1. All these polyamides are amorphous or partly crystalline and reveal good solubility in polar aprotic solvents and exhibit glass transition temperatures between 201 and 232 °C. Initial decomposition temperatures are in the range 300–367 °C and T10 is in the range of 376–414 °C indicating good thermal stability of these polyamides. The present observations suggest that these polyamides can find potential applications as high performance polymers.