A water‐dispersible conducting nanocomposite from suspension polymerisation of thiophene in presence of N‐vinylcarbazole

The polymerisation of a mixture of thiophene and N‐vinylcarbazole was achieved in aqueous suspension in the presence of nanodimensional alumina and FeCl₃ as oxidant. The resultant composite was found to contain both polythiophene (PTP) and poly(N‐vinylcarbazole) (PNVC) components even after reflux in benzene, which would remove any PNVC homopolymer. The presence of the individual polymer components was endorsed by FTIR spectroscopic analyses. Thermogravimetric analyses showed that the overall stabilities of the composite and the corresponding homopolymers were in the order: PTP–Al₂O₃ > PTP > PTP–PNVC–Al₂O₃ > PNVC. Differential thermal analyses studies showed the manifestation of two different exotherms corresponding to the presence of two different polymeric constituents in the PTP–PNVC–Al₂O₃ composite. Differential scanning calorimetry studies revealed two glass‐transition temperatures (T_g) suggesting the presence of two polymeric moieties in the PTP–PNVC composite. Scanning electron micrographs of the PTP–Al₂O₃ and PTP–PNVC–Al₂O₃ composites showed distinctive morphological patterns. Transmission electron microscopic images of the composite revealed that the average particle size varied between 20 and 80 nm. DC conductivities of the composites were of the order of 10^?6 S cm^?1. Copyright © 2003 Society of Chemical Industry     

Conducting composites of poly(N‐vinylcarbazole), polypyrrole,and polyaniline with 13X‐zeolite

N‐vinylcarbazole (NVC) was polymerized by 13X zeolite alone in melt (65°C) or in toluene (110°C) and a poly(N‐vinylcarbazole) (PNVC)‐13X composite was isolated. Composites of polypyrrole (PPY) and polyaniline(PANI) with 13X zeolite were prepared via polymerization of the respective monomers in the presence of dispersion of 13X zeolite in water (CuCl₂ oxidant) and in CHCl₃ (FeCl₃ oxidant) at an ambient temperature. The composites were characterized by Fourier transform infrared analyses. Scanning electron microscopic analyses of various composites indicated the formation of lumpy aggregates of irregular sizes distinct from the morphology of unmodified 13X zeolite. X‐ray diffraction analysis revealed some typical differences between the various composites, depending upon the nature of the polymer incorporated. Thermogravimetric analyses revealed the stability order as: 13X‐zeolite > polymer‐13X‐zeolite > polymer. PNVC‐13X composite was essentially a nonconductor, while PPY‐13X and PANI‐13X composites showed direct current conductivity in the order of 10^?4 S/cm in either system. However, the conductivity of PNVC‐ 13X composite could be improved to 10^?5 and 10^?6 S/cm by loading PPY and PANI, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 913–921, 2006     

A conducting nanocomposite of acetylene black with preformed poly‐N‐vinylcarbazole crosslinked by anhydrous FeCl3

A conducting nanocomposite of crosslinked poly‐N‐vinylcarbazole (CLPNVC) with nanodimensional acetylene black (AB) was prepared by oxidative crosslinking of preformed PNVC through pendant carbazole moieties in presence of anhydrous FeCl₃ as an oxidant and AB suspension in CHCl₃ medium at 65°C. The incorporation of CLPNVC moieties in the CLPNVC‐AB composite was endorsed by Fourier transform infrared analysis. Scanning electron microscopic analysis showed formation of lumpy aggregates with average sizes in the 130–330 nm ranges. The thermal stability of the CLPNVC‐AB composite was appreciably higher than that of the PNVC‐AB composite. The direct current conductivities of the composites were significantly enhanced relative to that of the PNVC homopolymer (10^?12–10^?16 S/cm) and varied in the range of 10^?4–10^?2 S/cm depending on the amount of AB loading in the CLPNVC‐AB composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 819–824, 2006     

Study on superabsorbent composite. XX. Effects of cation‐exchanged montmorillonite on swelling properties of superabsorbent composite containing sodium humate

In this work, the effects of different cation‐exchanged montmorillonite on water absorbency of poly(acrylic acid‐co‐acrylamide)/montmorillonite/sodium humate (PAA‐AM/MMT/SH) superabsorbent composite were systematically investigated under the same preparation conditions. The superabsorbents doped with different cation‐exchanged montmorillonite were characterized by Fourier‐transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy technologies. Swelling behaviors of developing superabsorbent composite in various cationic saline solutions (NaCl, CaCl₂, and FeCl₃) were also investigated. The water absorbencies of superabsorbent composite with 20 wt% MMT and 30 wt% SH are 638, 723, 682, and 363 g g⁻¹ in distilled water for incorporating natural Na⁺‐MMT, Li⁺‐exchanged MMT, Ca²⁺‐exchanged MMT, and Al³⁺‐exchanged MMT, respectively. The results showed that the cation‐exchange process had some obvious influences on final water absorbency of superabsorbent composite. NaCl, CaCl₂, and FeCl₃ solutions did not alter the swelling characteristics of the superabsorbent materials at a concentration of less than 0.01 mM, however, a concentration of greater than 0.1 mM caused a collapse in the swelling curves. The excellent swelling‐reswelling‐swelling behavior and lower swelling rate testified that Al³⁺‐exchanged MMT can act as an assistant crosslinker in the polymeric network. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Water‐dispersible nanocomposites of polyaniline and montmorillonite

The polymerization of aniline (ANI) in aqueous medium in the presence of (NH₄)₂S₂O₈ and montmorillonite (MMT) resulted in the formation of a nanocomposite (PANI–MMT). The inclusion of PANI in the composite was confirmed by FTIR studies. The extent of PANI loading in the composite increased with ANI concentration at a fixed oxidant/MMT amount and with the oxidant amount at a fixed ANI and MMT weight, but decreased with an MMT amount at a fixed ANI and oxidant level. TGA revealed a higher stability for the PANI–MMT composite relative to PANI and confirmed a PANI loading of ca. 51% in the composite. The conductivity increased in all the cases. XRD analysis revealed no expansion of the d₀₀₁ spacing at 9.8 Å, implying no intercalation of PANI within the MMT layers. Scanning electron micrography studies revealed interesting morphological features for the composites. Transmission electron micrography analysis revealed distinctive features and confirmed the formation of PANI–MMT composite particles of diameters in the 300‐ to 400‐nm range. These composites could be obtained as stable colloids in the presence of poly (N‐vinyl pyrrolidone) under selective conditions. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2948–2956, 2000     

A conducting composite based on poly(N‐vinylcarbazole)–formalin resin and acetylene black

A poly(N‐vinylcarbazole) (PNVC)–formalin (FO) resin (PNVC‐FO) was prepared via copolycondensation between N‐vinylcarbazole (NVC) and FO in the presence of dry HCl gas in toluene medium at 110°C. A highly conducting composite of PNVC‐FO resin with nanodimensional acetylene black (AB) was prepared by carrying out the polycondensation reaction in presence of a suspension of acetylene black (AB) in toluene. The inclusion of PNVC in the PNVC‐FO‐AB composite was confirmed by FT‐IR analysis. Scanning electron microscopic analyses of PNVC‐FO resin and PNVC‐FO‐AB composite revealed formation of spherical particles and aggregates of irregular shapes respectively. Thermogravimetric analyses revealed the overall stability order as: AB > PNVC‐FO‐AB composite > PNVC‐FO resin > PNVC homopolymer. In sharp contrast to PNVC and PNVC‐FO resin, which were both nonconducting (10^?12 to 10^?16 S/cm), the conductivity of the composites reached values between 0.75 S/cm and 6.54 S/cm corresponding to AB loading of 28–49 wt % respectively. Temperature versus conductivity studies revealed an initial increase in conductivity upto 200°C and current–voltage characteristics of the PNVC‐FO‐AB composite showed a linear trend consistent with Ohmic behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3837–3843, 2007     

Preparation and evaluation of nanocomposites of polyfuran with Al2O3 and montmorillonite clay

High yield oxidative polymerization of furan was accomplished in CHCl₃ solvent at 0 °C. A nanocomposite of polyfuran (PF)–Al₂O₃ was prepared through polymerization of furan in a suspension of nanodimensional Al₂O₃ in CHCl₃ at 0 °C. High yield polymerization of furan was also achieved in montmorillonite clay (MMT) without any extraneous oxidant. The formation of PF was confirmed by FTIR and elemental analysis. Thermogravimetric analyses revealed the following trends in thermal stability: PF < PF–Al₂O₃ < Al₂O₃ and PF < PF–MMT < MMT. Scanning electron microscopy showed the average particles sizes to be ca 51 nm and ca 40 nm for PF–Al₂O₃ and PF–MMT composites, respectively. The occurrence of a peak at 19.84 Å in the X‐ray diffraction pattern of the PF–MMT composite was indicative of the intercalation of PF in MMT lamellae. Transmission electron microscopic analyses for the PF–MMT composite also showed incorporation of PF moieties in‐between the MMT layers. The dc conductivity values (S cm^?1) of PF–FeCl₃, PF–Al₂O₃–FeCl₃, PF–MMT and PF–MMT–FeCl₃ systems were in the order of 10^?6, 10^?7, 10^?8 and 10^?7, respectively, and the values were significantly enhanced compared to the dc conductivity value of PF homopolymers (10^?11). Copyright © 2004 Society of Chemical Industry     

A nanocomposite of poly(N‐vinylcarbazole) with nanodimensional alumina

A nanocomposite of poly(N‐vinylcarbazole) (PNVC) and Al₂O₃ was prepared by precipitation of a preformed PNVC in a tetrahydrofuran solution onto an aqueous suspension of nanodimensional Al₂O₃. Prolonged extraction of a PNVC–Al₂O₃ composite by benzene failed to extract the loaded PNVC from the Al₂O₃, as shown by Fourier transform infrared studies. Scanning electron microscopy analyses revealed distinct morphological features of the composite, and transmission electron microscopy analyses confirmed that the particle sizes were in the range of 120–240 nm. Thermogravimetric analyses demonstrated the enhanced stability of the nanocomposite relative to the base polymer. Direct current conductivity of the PNVC–Al₂O₃ composites was found to be about 0.14 × 10^?6 S/cm. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2233–2237, 2003     

Improving photoluminescence of poly(9‐vinylcarbazole)/4,7‐diphenyl‐1,10‐phenanthroline/tris‐(8‐hydroxyquinoline) aluminum fibers via coaxial electrospinning

Solutions of poly(9‐vinylcarbazole)/4,7‐diphenyl‐1,10‐phenanthroline (PVK/Bphen) and poly(9‐vinylcarbazole)/tris‐(8‐hydroxyquinoline) aluminum (PVK/Alq₃) were individually delivered either to the inner or the outer needle of a coaxial spinneret for electrospinning to prepare green luminescent PVK/Bphen/Alq₃ composite fibers. The influence of both flow rate and applied voltage on the photoluminescence of the composite fibers was evaluated. Scanning electron microscopy showed ribbon‐like fibers with uneven surfaces and thickness of about 5 µm. Raman spectroscopy and fluorescence microscopy revealed that Bphen was homogenously dispersed in the PVK fibers; Alq₃ was not. Photoluminescence shows strong evidence that there are marked conditions where emission of the co‐electrospun PVK/Bphen/Alq₃ fibers significantly improved as compared with those produced by simple electrospinning. It is suggested that the enhanced dispersion of the Alq₃ allowed a more efficient energy transfer from the PVK to the Alq₃. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44019.     

Enhanced surface morphology and transport property of poly(N‐vinylcarbazole)/gold nanocomposite Langmuir–Schaefer films

A composite of poly(N‐vinylcarbazole) (PVK) containing gold nanoparticles (GNPs) was synthesized via simple solid‐state in situ bulk polymerization of N‐vinylcarbazole in the presence of GNPs at a high temperature. Both PVK and PVK–GNP composites were characterized by Fourier transform infrared (FTIR) and UV–vis spectroscopy. The surface morphology of the composites was studied by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy, and transmission electron microscopy (TEM). Thermal stability was identified via thermogravimetric analysis. The composites were fabricated into films using the Langmuir–Schaefer process. The enhancement in the characteristics of room temperature I–V, pressure–area isotherms, and photoelectrochemical behaviors was observed in the composite films. Results suggest that a charge transfer process occurs across the hybrid at the interface of the PVK–GNP composites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Synthesis of methyl methacrylate and N‐aryl itaconimide block copolymers via atom‐transfer radical polymerization

The paper describes the synthesis of block copolymers of methyl methacrylate (MMA) and N‐aryl itaconimides using atom‐transfer radical polymerization (ATRP) via a poly(methyl methacrylate)–Cl/CuBr/bipyridine initiating system or a reverse ATRP AIBN/FeCl₃·6H₂O/PPh₃ initiating system. Poly(methyl methacrylate) (PMMA) macroinitiator, ie with a chlorine chain‐end (PMMA‐Cl), having a predetermined molecular weight (M_n = 1.27 × 10⁴ g mol^?1) and narrow polydispersity index (PDI = 1.29) was prepared using AIBN/FeCl₃·6H₂O/PPh₃, which was then used to polymerize N‐aryl itaconimides. Increase in molecular weight with little effect on polydispersity was observed on polymerization of N‐aryl itaconimides using the PMMA‐Cl/CuBr/Bpy initiating system. Only oligomeric blocks of N‐aryl itaconimides could be incorporated in the PMMA backbone. High molecular weight copolymer with a narrow PDI (1.43) could be prepared using tosyl chloride (TsCl) as an initiator and CuBr/bipyridine as catalyst when a mixture of MMA and N‐(p‐chlorophenyl) itaconimide in the molar ratio of 0.83:0.17 was used. Thermal characterization was performed using differential scanning calorimetry (DSC) and dynamic thermogravimetry. DSC traces of the block copolymers showed two shifts in base‐line in some of the block copolymers; the first transition corresponds to the glass transition temperature of PMMA and second transition corresponds to the glass transition temperature of poly(N‐aryl itaconimides). A copolymer obtained by taking a mixture of monomers ie MMA:N‐(p‐chlorophenyl) itaconimide in the molar ratio of 0.83:0.17 showed a single glass transition temperature. Copyright © 2005 Society of Chemical Industry     

Preparation and photoconducting property of C60Cln‐m‐bonded poly(N‐vinylcarbazole) with C60Cln/CuCl/Bpy catalyst system

C₆₀Cl_n‐m bonded poly(N‐vinylcarbazole) (C₆₀‐PVK) has been synthesized by C₆₀Cln (the average value of n is 20)/CuCl/ Bpy (2,2′‐bipyridine) catalyst system and its structure was analyzed by UV‐Vis and proton NMR. The polymerization mechanism was proposed proceeding via a atom transfer radical polymerization (ATRP). The block copolymer of poly N‐vinylcarbazole‐block‐polystyrene can also be compounded by adding styrene after N‐vinylcarbazole polymerized completely in this polymerization system. The photoconducting properties of C₆₀Cl_n‐m‐bonded poly(N‐vinylcarbazole) was better than poly(N‐vinylcarbazole) initiated by AIBN. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 606–609, 2003     

Microwave absorption of poly‐N‐vinylcarbazole–polyaniline composites

Poly‐N‐vinylcarbazole–polyaniline (PANI) composites were synthesized using different loading concentration of aniline (0.025–0.1 M) for their microwave absorption characteristics. The obtained composites were studied by Fourier transform infrared spectroscopy, thermogravimetric analysis technique, and atomic force microscope for their chemical structure, thermal stability, and the surface modifications, respectively. The conductivity increased much with the increase of aniline concentration in the composites. The composite sheets exhibited a strong microwave absorption in the microwave range of 1–10 GHz and achieved a maximum absorption value of 33 dB. The position of absorbing peak shows a mixed trend moving from lower to higher and again to lower with an increasing the concentration of aniline in the poly‐N‐vinylcarbazole–PANI. The new polymer composite exhibited an appreciable electromagnetic interference shielding efficiency compared with the previously reported PANI composites. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers     

Complex formation of montmorillonite clay with polymers. Part 2: The use of montmorillonite clay–vinyl monomer complex as a comonomer in the copolymerization reaction of styrene–acrylonitrile monomers

The bulk copolymerization of styrene–acrylonitrile monomers using styrene‐N⁺–montmorillonite complex as a comonomer in the polymerization was studied. The X‐ray diffraction (XRD) analysis showed that part of the styrene‐N⁺–montmorillonite complex remained non‐dispersed (immiscible) and the copolymer was excluded from the interlayer of the immiscible part of the clay. The successive chemical extraction process revealed that a reasonable amount of the styrene–acrylonitrile copolymer was directly attached to the styrene‐N⁺–montmorillonite complex and enveloped the clay. Highly exfoliated clay lamella and nanospheres (3–5 nm) were observed by transmission electron microscopy (TEM). The montmorillonite clay assume two different morphologies, immiscible and exfoliated, on the basis of the XRD and TEM data. A simple method of calculation of the ratio of the exfoliated/immiscible amounts of the clay indicated that the amount of the styrene‐N⁺–montmorillonite complex exfoliated into separate lamella was 40 % (w/w) of the amount of the clay samples containing 2 % of the (styrene‐N⁺–montmorillonite complex) clay. This amount of exfoliated clay decreases with the increase of the concentration of the clay. The presence of the styrene‐N⁺–montmorillonite clay in the copolymerization reaction had a minor effect on both the copolymer composition and the molecular weight. Modification of the clay with the derivatized styrene monomer can achieve a nanocomposite using a percentage no more than 4 % (w/w) of complex in the copolymer. Copyright © 2004 Society of Chemical Industry     

Synthesis and antimicrobial activity of the Schiff base from polyoxyalkylene‐montmorillonite nanocomposites and aldehydes

Vanillin (4‐hydroxy‐3‐methoxy benzaldehyde) and 5‐formylamino salicylic acid microbicides were reacted with polyoxyalkylene‐montmorillonite (D_230–2000‐MMT) nanocomposites. The microstructure of these Schiff base nanocomposites was characterized by TEM and XRD. D_230–2000‐MMT nanocomposites were prepared by an ion exchange process of sodium montmorillonite (Na‐MMT) and NH₃ ⁺ groups in polyoxyalkylene amine hydrochloride with three different molecular masses of D₂₃₀, D₄₀₀, and D₂₀₀₀. Wide‐angle X‐ray diffraction confirms the intercalation of the polymer between the silicate layers. Electrostatic interaction between the positively charged NH₃ ⁺ groups and the negatively charged surface of MMT was observed. The nanocomposites were tested for antimicrobial activity against the Gram‐negative bacteria (Escherichia coli NCIM 2065), Gram‐positive bacteria (Bacillus subtillus ATCC), and fungi (Candida albicans SC5314 and Cryptococcus neoformans). The D₂₀₀₀‐MMT/vanillin Schiff base nanocomposite strongly inhibited the growth of all microorganisms that can be used in different applications. The amount of loaded polymer and the structure of the nanocomposite play an important role in inhibiting the bacterial and fungal strains. It is found that the Schiff base nanocomposite affect the morphology, oxygen consumption, and the release of cytoplasmic constituents such as potassium (K⁺), sodium (Na⁺), and calcium (Ca²⁺) ions leading to death of the cells. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Linear low‐density polyethylene‐g‐poly(acrylic acid)/(organo‐montmorillonite) hydrogel composite as hydrogel electrolytes for zinc–carbon batteries

A hydrogel composite that has been prepared by using waste linear low‐density polyethylene, acrylic acid, and organo‐montmorillonite (LLDPE‐g‐PAA/OMMT) is used as a hydrogel electrolyte. An absorbency test was used to determine the percentage of ZnCl₂ solution absorbed by the hydrogel composite. The swelling behavior of the hydrogel composite in the ZnCl₂ solution was then studied. The highest absorbency was recorded when the concentration of ZnCl₂ solution was 3 M. The conductivity of ZnCl₂‐hydrogel composite electrolytes is dependent on the solution's concentration. A mixture of ZnCl₂ solution with hydrogel composite yields a good hydrogel composite electrolyte with a conductivity of 0.039 S cm^?1 at 3 M ZnCl₂. The hydrogel composite electrolyte was used to produce zinc‐carbon cells. The fabricated cell gives capacity of 7.8 mAh, has an internal resistance of 9.9 Ω, a maximum power density of 15.78 mWcm^?2, and a short‐circuit current density of 43.75 mAcm^?2 for ZnCl₂‐hydrogel composite electrolytes. J. VINYL ADDIT. TECHNOL., 22:279–284, 2016. © 2014 Society of Plastics Engineers     

Nanocomposites based on poly(butylene adipate‐co‐terephthalate) and montmorillonite

Nanocomposites based on biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) and layered silicates were prepared by the melt intercalation method. Nonmodified montmorillonite (MMT) and organo‐modified MMTs (DA‐M, ODA‐M, and LEA‐M) by the protonated ammonium cations of dodecylamine, octadecylamine, and N‐lauryldiethanolamine, respectively, were used as the layered silicates. The comparison of interlayer spacing between clay and PBAT composites with inorganic content 3 wt % measured by X‐ray diffraction (XRD) revealed the formation of intercalated nanocomposites in DA‐M and LEA‐M. In case of PBAT/ODA‐M (3 wt %), no clear peak related to interlayer spacing was observed. From morphological studies using transmission electron microscopy, the ODA‐M was found to be finely and homogeneously dispersed in the matrix polymer, indicating the formation of exfoliated nanocomposite. When ODA‐M content was increased, the XRD peak related to intercalated clay increased. Although the exfoliated ODA‐M (3 wt %) nanocomposite showed a lower tensile modulus than the intercalated DA‐M and LEA‐M (3 wt %) composites, the PBAT/ODA‐M composite with inorganic content 5 wt % showed the highest tensile modulus, strength, and elongation at break among the PBAT composites with inorganic content 5 wt %. Their tensile properties are discussed in relation to the degree of crystallinity of the injection molded samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 386–392, 2005     

One‐pot synthesis of a few nanocomposites with poly(N‐vinylcarbazole) and CdS,Ag, Pd50–Ag50, and Pt50–Ru50 nanoparticles with γ irradiation

The one‐pot synthesis of nanocomposites of a conductive poly(N‐vinylcarbazole) (PVK) with CdS, Ag, Pd₅₀–Ag₅₀, and Pt₅₀–Ru₅₀ nanoparticles was performed with γ irradiation in a tetrahydrofuran–water mixture (3/1 vol %). For comparison, the CdS, Ag, Pd₅₀–Ag₅₀, and Pt₅₀–Ru₅₀ nanoparticles were also prepared with γ irradiation with polyvinylpyrrolidone as a stabilizer. Ultraviolet–visible spectroscopy, transmission electron microscopy, X‐ray diffraction analysis, and photoluminescence spectroscopy were used for the characterization of CdS, Ag, Pd₅₀–Ag₅₀, and Pt₅₀–Ru₅₀ nanoparticles and nanocomposites of PVK with CdS, Ag, Pd₅₀–Ag₅₀, and Pt₅₀–Ru₅₀ nanoparticles. The absorption spectrum of the CdS‐nanoparticle‐based composite revealed a quantum confinement effect. The emission spectrum of the composite with CdS nanoparticles and PVK indicated the block effect of PVK for surface recombination. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1809–1815, 2006     

Effect of montmorillonite on the properties of thermosensitive poly(N‐isopropylacrylamide) composite hydrogels

Thermosensitive composite hydrogels containing various amounts of sodium montmorillonite (NaMM) and poly(N‐isopropylacrylamide) (pNIPAAm) were synthesized. Their equilibrium degree of swelling (DS) was measured in NaCl solutions of different ionic strength and at various temperatures. The DS decreased when increasing the clay content and no substantial shift in the phase transition temperature was noticed. The composite hydrogels investigated had a NaMM content ranging between 1.0 and 5.7 wt % (in 0.1M NaCl at 25°C). A considerable enhancement in the response to thermal stimuli was observed for NaMM contents >2–3 wt %. It is suggested that when the NaMM concentration approaches a critical value, the clay platelets can inhibit the formation of the hydrophobic skin layer that hinders shrinking in conventional pNIPAAm hydrogels. The effect of montmorillonite on the mechanical properties of the hydrogels was investigated by uniaxial compression tests, which showed that the modulus increases with the NaMM content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1964–1971, 2004     

Synthesis and characterization of water soluble poly(N‐acetyl)iminoethylene and poly(ethyleneimine) by ion‐exchanged clay montmorillonite

The cationic polymerization of 2‐méthyl‐2‐oxazoline was carried out at 0°C in acetonitrile using an acid‐exchanged montmorillonite as acid solid ecocatalyst (Maghnite‐H⁺). The effect of the amount of catalyst, solvent, and times of polymerization on yield and viscosity of polymer was studied. A typical reaction product (PMOX) was analyzed by infrared and nuclear magnetic resonance spectroscopy as well as by gel‐permeation chromatography and MALDI‐TOF MS. The polymers presented similar spectrometric results and narrow molecular weight distribution. The poly(N‐acetyl)iminoethylene was hydrolyzed in acid medium obtaining a linear poly(ethyleneimine). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3741–3750, 2006