A facile and green method for the production of novel and potentially biocompatible poly(amide-imide)/ZrO2–poly(vinyl alcohol) nanocomposites containing trimellitylimido-l-leucine linkages

We have reported the synthesis of nanocomposites (NCs) based on chiral poly(amide-imide) (PAI) and modified zirconium nanoparticles (ZrO₂ NPs) with poly(vinyl alcohol) (PVA). The optically active PAI was prepared under the green condition via the direct polycondensation of biocompatible trimellitylimido-l-leucine diacid and 4,4′-diaminediphenylsulfone in the presence of tetrabutylammonium bromide and triphenyl phosphite as the green solvent and the activating agents. NPs, due to a high surface to volume ratio, have a great tendency to agglomerate in the polymer matrix. So, at first, the surface of ZrO₂ NPs was modified with the PVA as the biodegradable and biocompatible polymer. Afterward, the modified NPs were added into the PAI matrix in the ethanol solution under ultrasonic irradiations. The obtained PAI/ZrO₂–PVA NCs (PZ–PNC)s were characterized by various techniques. The Fourier transform infrared proved the formation of PZ–PNCs. Field emission-scanning electron microscopy exhibited that ZrO₂ NPs had good dispersion in the PAI matrix, and transmission electron microscopy indicated that ZrO₂ NPs were coated by a nanometer-thick layer of PVA that was about 10 nm. X-ray diffraction analysis showed that the ZrO₂ NPs retained their crystalline structure after they were added in the PAI matrix. Thermogravimetric analysis illustrated that the prepared PZ–PNCs had a better thermal stability than the neat PAI.     

The utilization of poly(amide-imide)/SiO2 nanocomposite as nanofiller for strengthening of mechanical and thermal properties of poly(vinyl alcohol) nanocomposite films

The present investigation reports the preparation and characterization of the thermally stable poly(vinyl alcohol)/(poly(amide-imide)-SiO₂) nanocomposite (PVA/PAI-SiO₂ NC) films. For this reason, the surface of SiO₂ nanoparticles (NPs) was modified with N-trimellitylimido-l-methionine and subsequently, 5 wt.% of modified SiO₂ NPs were dispersed in the PAI matrix via sonochemical reaction. The resulting NC was studied by different techniques. Finally, the PAI-SiO₂ NC was employed as nanofiller and was incorporated into the PVA matrix for the enhancement of its mechanical and thermal properties. The synthesized NCs were studied by Fourier transform infrared and X-ray diffraction spectroscopy analysis. The surface topography and morphology of the NCs were studied by atomic force microscopy techniques, field emission scanning electron microscopy and transmission electron microscopy. The micrographs demonstrated that the nanofillers were homogeneously dispersed in the PVA matrix. The thermo gravimetric analysis curves indicated that the thermal decomposition of the PVA/PAI-SiO₂ NC films shifted toward higher temperature in comparison with the pure PVA. The effect of nanofiller on the mechanical properties of NC films was also explored.     

Production and characterization of nanocomposites based on poly(amide-imide) containing 4,4′-methylenebis(3-chloro-2,6-diethylaniline) using nano-TiO2 surface-coupled by 3-aminopropyltriethoxysilane

In this work, the poly(amide-imide) (PAI) was synthesized from the polymerization reaction of 4,4′-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) as a diacid with 4,4′-methylenebis(3-chloro-2,6-diethylaniline) under green condition using molten tetra-n-butylammonium bromide and triphenylphosphite. Ultrasonic technique was used for preparation of PAI/TiO₂ nanocomposites (PAI/TiO₂ NCs). For the improvement of TiO₂ nanoparticles (NPs) dispersion and enhancing interactions between NPs and polymeric matrix the surface of TiO₂ was successfully modified by silane coupling agent (3-aminopropyltriethoxysilane). The resulting NCs were characterized by FT-IR, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The TGA of the obtained NCs proves the enhancement in the thermal stability with an increase in the percentage of titania NPs. TEM and FE-SEM images showed that the NPs were uniformly dispersed in the polymer matrix. The shielding effect of nano TiO₂ under UV radiation was examined by UV–vis.     

Thermal properties and non‐isothermal crystallization behavior of biodegradable poly(p‐dioxanone)/poly(vinyl alcohol) blends

Blends of two biodegradable semicrystalline polymers, poly(p‐dioxanone) (PPDO) and poly(vinyl alcohol) (PVA) were prepared with different compositions. The thermal stability, phase morphology and thermal behavior of the blends were studied by using thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). From the TGA data, it can be seen that the addition of PVA improves the thermal stability of PPDO. DSC analysis showed that the glass transition temperature (T_g) and the melting temperature (T_m) of PPDO in the blends were nearly constant and equal to the values for neat PPDO, thus suggesting that PPDO and PVA are immiscible. It was found from the SEM images that the blends were phase‐separated, which was consistent with the DSC results. Additionally, non‐isothermal crystallization under controlled cooling rates was explored, and the Ozawa theory was employed to describe the non‐isothermal crystallization kinetics. Copyright © 2006 Society of Chemical Industry     

Novel chiral poly(amide-imide)/surface modified SiO2 nanocomposites based on N-trimellitylimido-l-methionine: Synthesis and a morphological study

In the present investigation, novel poly(amide-imide) (PAI)/SiO₂ nanocomposites (NCs) containing l-methionine moiety in the main chain were prepared via a simple and fast ultrasonic irradiation process. PAI was synthesized by direct poly condensation reaction of N-trimellitylimido-l-methionine with 4,4′-diamino diphenylether in molten tetra-n-butyl ammonium bromide/triphenyl phosphite as a green condensing agent. Due to the high surface energy and tendency for agglomeration, the surface of SiO₂ NPs was modified with chiral diacid. The obtained NCs were characterized by Fourier transform-infrared (FT-IR) spectroscopy, thermogravimetry analysis, X-ray powder diffraction, field emission-scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The FT-IR spectroscopy indicated that the chiral diacid as the coupling agent was attached on the surface of SiO₂ NPs. FE-SEM, and TEM images showed that SiO₂ NPs were dispersed rather homogeneously in the PAI matrix.     

Using Mg‐Al‐layered double hydroxide intercalated with chiral dicarboxylic acid for the reinforcement of isoleucine amino acid containing poly(amide‐imide)

A series of bionanocomposite (BNC) materials based on isoleucine containing poly(amide‐imide) (PAI) and modified MgAl‐layered double hydroxide (LDH) were prepared by solution intercalation method for the first time. An optically active PAI was synthesized by direct polycondensation reaction of N,N'‐(pyromellitoyl)‐bis‐isoleucine with 3,5‐diamino‐N‐(thiazol‐2‐yl)benzamide under green conditions. Organically modified LDH was prepared via ion exchange reaction of MgAl‐LDH in a solution of N,N'‐(pyromellitoyl)‐bis‐l‐ isoleucine in distilled water. X‐ray diffraction (XRD) results of modified LDH show an increase in interlayer distance as compared to the unmodified one. The obtained polymer and modified LDH were used to prepare chiral and high‐performance hybrid materials. Fourier transform infrared spectroscopy, XRD, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis (TGA) techniques were used to study the morphology and thermal properties of the obtained hybrid materials. TGA data indicated an increase in thermal stability of the BNCs as compared to the pure polymer. POLYM. COMPOS., 37:3288–3295, 2016. © 2015 Society of Plastics Engineers     

Preparation and characterization of reinforced poly(vinyl alcohol) films by a nanostructured,chiral, L-leucine based poly(amide-imide)/ZrO2 nanocomposite through a green method

In the present investigation, at first, the surface of ZrO₂ nanoparticles was modified with a bioactive and biocompatible diacid based on leucine amino acid as a coupling agent. The grafting of diacid on the surface of ZrO₂ was confirmed by Fourier transform infrared spectroscopy and thermogravimetric analysis. Then, the synthesis of poly(amide-imide)/ZrO₂ nanocomposite (PAI/ZrO₂ NC) was performed through ultrasonic technique. The obtained NCs demonstrated good thermal stability. Field emission scanning electron microscopy and transmission electron microscopy analysis showed that the average diameter of NP was around 15–20 nm. Finally, the resulting NC, was used as a nano-filler and was incorporated into the poly(vinyl alcohol) (PVA) in order to improve its mechanical and thermal properties. The PVA/PAI–ZrO₂ NC films were characterized by different techniques. The data indicated that the thermal and mechanical properties of the PVA/PAI–ZrO₂ NC were enhanced. It was attributed to the good dispersion of filler into the PVA matrix as a result of hydrogen bonding.     

Novel nanocomposites obtained by dispersion of LDH modified with N‐tetrabromophthaloyl‐glutamic in poly(amide‐imide) having N‐trimellitylimido‐l‐leucine and 4,4′‐diaminodiphenylether units

Layered double hydroxides (LDHs) have attracted much attention as nanofillers in polymer nanocomposites (NCs) due to their particular surface structural, positively charged layer and so on. In this study, a chiral diacid was synthesized by the reaction of tetrabromophthalic anhydride and glutamic acid. LDH was modified by co‐precipitation of aluminum nitrate, magnesium nitrate, and glutamic acid containing diacid. Chiral poly(amide‐imide) (PAI) was synthesized by direct polycondensation reaction of N‐trimellitylimido‐l ‐leucine and 4,4′‐diaminodiphenylether. Different NCs of the obtained modified LDHs and the chiral PAI were prepared in a short time using ultrasonic technique. The morphology and the structure of the obtained samples were characterized by Fourier transform infrared, thermogravimetric analysis (TGA), field emission scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction analysis. TGA of the NCs showed a special order in thermal stability in compression with the neat PAI owing to the uniform distribution of the nanofillers. POLYM. COMPOS., 37:1323–1329, 2016. © 2014 Society of Plastics Engineers     

Surface coating of α-Al2O3 nanoparticles with poly(vinyl alcohol) as biocompatible coupling agent for improving properties of bio-active poly(amide-imide) based nanocomposites having l-phenylalanine linkages

Nanocomposites (NCs) containing metal oxide nanoparticles (NPs) as fillers are used in a wide range of applications and in various fields. Poly(vinyl alcohol) (PVA) is an attractive polymer because of its many desirable applications and characteristics. In this investigation, at first, the surface of alumina (α-Al₂O₃) NPs was modified with PVA as a biocompatible modifier. Then, the optically active poly(amide-imide) (PAI) nanostructure was prepared by using molten tetrabutylammonium bromide as a molten ionic liquid and triphenyl phosphite as the condensing agent. Finally, the modified α-Al₂O₃ (α-Al₂O₃-PVA) NPs were incorporated into the PAI matrix for the preparation of PAI/Al₂O₃-PVA NCs (PAPNCs). To investigate effect and nature of coating on the surface of the α-Al₂O₃ NPs and preparation of PAPNCs, the samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The surface morphology examination demonstrated the monodispersed characteristics of α-Al₂O₃ NPs after surface modification with the PVA and incorporation into the PAI matrix.     

Crystallization of poly(ethylene oxide) embedded with surface‐modified SiO2 nanoparticles

The crystallization of poly(ethylene oxide) (PEO) in the presence of silica nanoparticles (SiO₂ NPs) was investigated in terms of heterogeneous nucleation of SiO₂ NPs using polarizing optical microscopy and differential scanning calorimetry. The content and surface functionality of SiO₂ NPs were considered as the main factors affecting crystallization, and the effect of annealing time and temperature was also examined. The SiO₂ NPs acted as heterogeneous nucleates during the crystallization process, thereby enhancing the nucleation density and limiting the spherulitic growth rate. A kinetics study of non‐isothermal crystallization showed that the crystallization rate of 5 wt% SiO₂/PEO nanocomposite was ca 2.1 times higher than that of neat PEO. In addition, among various surface‐functionalized SiO₂ nanoparticles, alkyl‐chain‐functionalized SiO₂ NPs were favorable for achieving a higher crystallization rate due to the enhanced compatibility between the SiO₂ NPs and PEO chains. © 2012 Society of Chemical Industry     

Preparation and characterization of novel optically active poly(amide‐imide)/α‐Fe2O3 nanocomposites containing l‐alanine moieties

An optically active poly(amide‐imide) (PAI) was synthesized from the polymerization reaction of N,N′‐(Pyromellitoyl)‐bis‐l ‐alanine diacid chloride with 2,5‐diaminotoluene. The obtained inorganic metal oxide nanocomposites composed of PAI/nanostructured hematite (α‐Fe₂O₃) were synthesized through ultrasonic irradiation. The resulting nanocomposites were characterized by Fourier transform infrared spectroscopy, powder X‐ray diffraction, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The TEM results indicated that the nanoparticles were dispersed homogeneously in PAI matrix on nanoscale. TGA confirmed that the heat stability of the nanocomposites was improved in the presence of α‐Fe₂O₃ nanoparticles. POLYM. COMPOS., 37:1805–1811, 2016. © 2014 Society of Plastics Engineers     

Synthesis and characterization of semi‐interpenetrating networks based on poly(dimethylsiloxane) and poly(vinyl alcohol)

Semi‐interpenetrating networks (Semi‐IPNs) with different compositions were prepared from poly(dimethylsiloxane) (PDMS), tetraethylorthosilicate (TEOS), and poly(vinyl alcohol) (PVA) by the sol‐gel process in this study. The characterization of the PDMS/PVA semi‐IPN was carried out using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and swelling measurements. The presence of PVA domains dispersed in the PDMS network disrupted the network and allowed PDMS to crystallize, as observed by the crystallization and melting peaks in the DSC analyses. Because of the presence of hydrophilic (? OH) and hydrophobic (Si? (CH₃)₂) domains, there was an appropriate hydrophylic/hydrophobic balance in the semi‐IPNs prepared, which led to a maximum equilibrium water content of ～ 14 wt % without a loss in the ability to swell less polar solvents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Efficient functionalization of multi‐walled carbon nanotubes with p‐aminophenol and their application in the fabrication of poly(amide‐imide)‐matrix composites

The ultrasonically assisted preparation and characterization of poly(amide‐imide) (PAI) composites containing functionalized multi‐walled carbon nanotubes (MWCNTs) are reported. To improve the dispersion in and compatibility with the polymer matrix, the MWCNTs were surface‐modified with p‐aminophenol (p‐AP) under microwave irradiation. The process is fast, one‐pot, easy and results in a high degree of functionalization as well as dispersibility in organic solvents. The p‐AP‐functionalized MWCNTs (MWCNTs‐AP) were analysed by means of field emission and transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction and thermogravimetric analysis (TGA). The results consistently confirm the formation of p‐AP functionalities on MWCNTs which are able to undergo additional reactions, while the structure of the MWCNTs remains relatively intact. MWCNTs‐AP/PAI hybrid films were prepared with various MWCNTs‐AP contents (5–15 wt%) using a solution‐casting technique. Microscopic observations show that the dispersion of the MWCNTs‐AP is improved as a result of the organic groups on the MWCNT surface and functional groups in the PAI structure. The properties of the obtained composites were characterized extensively using the aforementioned techniques. TGA results show that the hybrid films exhibit a good thermal stability. Tensile mechanical testing was performed for the prepared composites, the results of which indicate an increase in the elastic modulus and tensile strength with increasing MWCNTs‐AP content. © 2013 Society of Chemical Industry     

Effective methodology for the production of novel nanocomposite films based on poly(vinyl chloride) and zinc oxide nanoparticles modified with green poly(vinyl alcohol)

Ultrasonic irradiation and solution dispersion methods were used to organize transparent worthwhile poly(vinyl chloride) (PVC) nanocomposite (NC) films which contain different amounts of modified zinc oxide nanoparticles (NP)s. First, modification of ZnO NPs was accomplished by biocompatible poly(vinyl alcohol) (PVA) to increase NCs compatibility and dispersity in the PVC matrix. The investigation followed by the fabrication and characterization of PVC/ZnO‐PVA NCs which obtained via fast and facile ultrasonication irradiation. The measurements of X‐ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and field emission scanning electron microscopy were used for the characterization of properties, structure and morphology of the obtained NPs and their NCs. Furthermore, thermal and optical properties of the resulting NCs were also carried out by thermogravimetric analysis, ultraviolet‐visible transmission, and absorption spectra. Morphology results demonstrate well‐dispersed characteristics of ZnO‐PVA NPs incorporated in the PVC matrix which resulted from modification. Also, modified ZnO NPs enhanced mechanical properties of prepared NC films. Prepared NCs could be categorized as self‐extinguishing materials on the basis of the limiting oxygen index values. POLYM. COMPOS., 38:1800–1809, 2017. © 2015 Society of Plastics Engineers     

Thermal characteristics of interpenetrating polymer networks composed of poly(vinyl alcohol) and poly(N‐isopropylacrylamide)

Interpenetrating polymer networks (IPNs) composed of poly(vinyl alcohol) (PVA) and poly(N‐isopropylacrylamide) (PNIPAAm) were prepared by the sequential‐IPN method. The thermal characterization of the IPNs was investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Depression of the melting temperature (T_m) of the PVA segment in IPNs was observed with increasing PNIPAAm content using DSC. DEA was employed to ascertain the glass‐transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_g values, indicating the presence of phase separation in the IPNs. The thermal decomposition of IPNs was investigated using TGA and appeared at near 200°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 881–885, 2003     

Efficient preparation of hybrid nanocomposite coatings based on poly(vinyl alcohol) and silane coupling agent modified TiO2 nanoparticles

In the present investigation, at first, the surface of titanium dioxide (TiO₂) nanoparticles was modified with γ-aminopropyltriethoxy silane as a coupling agent. Then a new kind of poly(vinyl alcohol)/titanium dioxide (PVA/TiO₂) nanocomposites coating with different modified TiO₂ loading were prepared under ultrasonic irradiation process. Finally, these nanocomposites coating were used for fabrication of PVA/TiO₂ films via solution casting method. The resulting nanocomposites were fully characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), thermogravimetric analysis/derivative thermal gravimetric (TGA/DTG), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The TEM and SEM results indicated that the surface modified nanoparticles were dispersed homogeneously in PVA matrix on nanoscale and based on obtained results a possible mechanism was proposed for ultrasonic induced nanocomposite fabrication. TGA confirmed that the heat stability of the nanocomposite was improved. UV–vis spectroscopy was employed to evaluate the absorbance and transmittance behavior of the PVA/TiO₂ nanocomposite films in the wavelength range of 200–800 nm. The results showed that this type of films could be used as a coating to shield against UV light.     

In situ preparation of Au or Ag nanoparticles in the presence of hyperbranched poly(amidoamine)s with hydrophobic end‐groups as nanoreactors and reductants

Hyperbranched poly(amidoamine)s with methyl ester terminals (HPAMAM‐COOCH₃) were used as nanoreactors and reductants to prepare gold or silver nanoparticles (Au NPs or Ag NPs). HPAMAM‐COOCH₃ could bind AuCl₄ ⁻ (or Ag⁺) and then reduce AuCl₄ ⁻ (or Ag⁺) into Au NPs (or Ag NPs) through their internal amines, while the external methyl ester groups prevented the aggregation of polymers. The formation of Au NPs or Ag NPs was verified using transmission electron microscopy (TEM), ultraviolet‐visible spectroscopy (UV‐Vis), X‐Ray powder diffraction (XRD), Fourier‐transform infrared spectroscopy (FT‐IR), and thermogravimetric analysis (TGA), confirming the formation of Au NPs or Ag NPs with small particle size and low size distribution.POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Thermal properties and morphology of a poly(vinyl alcohol)/silica nanocomposite prepared with a self‐assembled monolayer technique

A poly(vinyl alcohol) (PVA)/silica (SiO₂) nanocomposite was prepared with a novel self‐assembled monolayer technique, and its morphology and thermal properties were studied with different material characterization instruments. The treated SiO₂ nanoparticles were dispersed in the PVA matrix homogeneously, and the thermal properties of the nanocomposite were markedly improved in comparison with those of pure PVA. Under the same isothermal heating conditions, the decomposition of the nanocomposite was delayed significantly in comparison with that of PVA. The thermal degradation of the nanocomposite was a two‐step reaction, including the degradation of the side chain and main chain. The products of side‐chain degradation were mainly carboxylic acid, whereas main‐chain degradation primarily produced carbon dioxide and low‐molecular‐weight conjugated polyene. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1436–1442, 2005     

Thermal characteristics of poly(vinyl alcohol) and poly(vinylpyrrolidone) IPNs

Interpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) (PVA) and 1‐vinyl‐2‐pyrrolidone (VP) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone (DMPAP) and methylene bisacrylicamide (MBAAm) as initiator and crosslinker, respectively. The thermal characterization of the IPNs was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). Depressions of the melting temperatures of PVA segments in IPNs were observed with increasing VP content via the DSC. The DEA was employed to ascertain the glass transition temperature (T_g) of IPNs. From the result of DEA, IPNs exhibited two T_gs indicating the presence of phase separation in the IPN. The thermal decomposition of IPNs was investigated using TGA and appeared at near 270°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1844–1847, 2002     

A novel method of hyperbranched poly(amide‐ester) modifying nano‐SiO2 and study of mechanical properties of PVC/nano‐SiO2 composites

A new method of surface chemical modification of nano‐SiO₂ was proposed in the paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano‐SiO₂ reacted with AB₂‐type monomer (N,N‐dihydroxyethyl‐3‐amino methyl propionate) by one‐step polycondensation. And the product's Fourier transform infrared graphs and transmission electron microscopy (TEM) images proved that hyperbranched poly(amine‐ester) (HPAE) was grafted from nano‐SiO₂ surface successfully. Moreover, polyvinyl chloride (PVC)/modified nano‐SiO₂ composites were made by melt‐blending. The composites' structures and mechanical properties were characterized by TEM, scanning electron microscopy, and electronic universal testing machine. The results showed that nano‐SiO₂ grafted by HPAE increased obviously in dispersion in PVC matrix, and mechanical properties of PVC were effectively improved. Additionally, it was found that mechanical properties of PVC/nano‐SiO₂ composites reached the best when weight percent of nano‐SiO₂ in PVC matrix was 1%. Compared with crude PVC, the tensile strength of HPAE grafted nano‐SiO₂/PVC composite increased by 24.68% and its break elongation, flexural strength, and impact strength increased by 15.73, 4.07, and 184.84%, respectively. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers