H NMR study of temperature-induced phase transitions in D2O solutions of poly(N-isopropylmethacrylamide)/poly(N-isopropylacrylamide) mixtures and random copolymers

¹H NMR spectroscopy was used to investigate temperature-induced phase transitions in D₂O solutions of poly(N-isopropylmethacrylamide) (PIPMAm)/poly(N-isopropylacrylamide) (PIPAAm) mixtures and P(IPMAm/IPAAm) random copolymers of various composition on molecular level. While two phase transitions were detected for PIPMAm/PIPAAm mixtures, only single phase transition was found for P(IPMAm/IPAAm) copolymers. The phase transition temperatures of PIPAAm component (appears at lower temperatures) are not affected by the presence of PIPMAm in the mixtures; on the other hand, the temperatures of the phase transition of PIPMAm component (appears at higher temperatures) are affected by the phase separation of the PIPAAm component and depend on concentration of the solution. For P(IPMAm/IPAAm) random copolymers, a departure from the linear dependence of the transition temperatures on the copolymer composition was found for a sample with 75 mol% of IPMAm monomeric units.     

Toward an understanding of thermoresponsive transition behavior of hydrophobically modified N-isopropylacrylamide copolymer solution

Poly(N-isopropylacrylamide-co-vinyl laurate)(PNIPAAm-co-VL) copolymers were prepared at various feed ratios via conventional radical random copolymerization. The formation, composition ratios and molecular weight of copolymers were examined. The thermoresponsive behaviors of PNIPAAm and PNIPAAm-co-VL solutions at low and high concentrations were intensively investigated by turbidity measurement, Micro-DSC, temperature-variable state fluorescence, ¹H NMR and dynamic light scattering (DLS). Several important results were obtained that (1) incorporation of PVL results in much lower and broader LCST regions of the copolymer solutions, and facilitates the formation of hydrophobic microdomains far below LCST, causing a pronounced aggregation in solutions (2) temperature-variable ¹H NMR spectra shows that during the phase transition, the ‘penetration’ of PNIPAAm into the hydrophobic core is a process accompanied with a transition of isopropyl from hydration to dehydration as well as a self-aggregation of hydrophobic chains at different temperature stages (3) according to the ¹H NMR spectra of polymer solutions obtained at varied temperatures, the microdomains from hydrophobic VL moieties have a different accessibility for isopropyl groups and the entire chains during phase transition (4) temperature-variable DLS demonstrates that the temperature-induced transition behavior of copolymers is supposedly divided into three stages: pre-LCST aggregation (<20 °C), coil-globule transition at LCST (20-25 °C) and post-LCST aggregation (>25 °C).     

Novel network polymer electrolytes containing fluorine and sulfonic acid lithium prepared by ultraviolet polymerization

Poly(vinyl alcohol) (PVAL) and vinyl acetate‐vinyl alcohol copolymers (VAVAL) were esterified with 3,5‐dinitrobenzoyl chloride using the cycled urea N,N′‐dimethylpropyleneurea (1,3‐dimethyl‐3,4,5,6‐tetrahydro‐2(1H)‐pyrimidinone) (DMPU) as the solvent. Vinyl alcohol‐vinyl‐3,5‐dinitrobenzoate copolymers (VALVDNB) and vinyl acetate‐vinyl‐3,5‐dinitrobenzoate copolymers (VAVDNB) were obtained. High degrees of esterification were obtained when PVAL was esterified (86%). The degree of transformation was determined by ¹H‐NMR as well as by chemical analysis, and the structure of the resulting polymers by means of IR spectroscopy and ¹H‐ and ¹³C‐NMR. The microstructure of PVA, PVAL, VAVAL copolymers and VALVDNB copolymers were determined from ¹H‐ and ¹³C‐NMR techniques. The sequence distributions for VAVAL copolymers prepared by base‐catalyzed transesterification of PVA were blocky, while the distributions were close to random for VALVDNB copolymers obtained by esterification of PVAL. Thermal properties were studied by DSC. The T_g values of VAVAL, VALVDNB, and VAVDNB copolymers as a function of copolymer compositions were determined. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Functional bioengineering copolymers. II. Synthesis and characterization of amphiphilic poly(N-isopropyl acrylamide-co-maleic anhydride) and its macrobranched derivatives

Radical-initiated copolymerization of N-isopropyl acrylamide (NIPA) with maleic anhydride (MA) and macromolecular reactions of synthesized poly(NIPA-co-MA) with polyethyleneglycol (PEG with a methoxy chain end and molecular weight of 2000 g mol⁻¹) and polyethyleneimine (PEI with molecular weight of 2000 g mol⁻¹) have been studied as a way to obtain new reactive amphiphilic water-soluble polymers potentially useful as carriers for gene delivery. Structure, composition and thermal behaviour of synthesized copolymers and their macrobranched architectures are determined by FTIR, ¹H and ¹³C NMR spectroscopy, elemental (N content) and chemical (acid number) analysis and differential scanning calorimetry, differential thermal and thermal gravimetric methods. It is shown that synthesized copolymers with given composition have low critical solution temperature (LCST) in the range of 30.2-46.4 °C at pH values of 4.0-7.4, which suggest the possibility of their biomedical applications.     

Effect of composition and stereoregularity on phase-transition behavior of aqueous N-ethylacrylamide/N-n-propylacrylamide copolymer solutions

Radical copolymerizations of N-ethylacrylamide and N-n-propylacrylamide (NNPAAm) at various ratios were carried out at −40 °C, in toluene in the presence of 3-methyl-3-pentanol, or in N-ethylacetamide. Syndiotactic-rich copolymers with racemo diad contents of 67.1–70.2%, and isotactic-rich copolymers with meso diad contents of 60.9–64.5% were prepared. Syndiotactic-rich copolymers with NNPAAm compositions of ≥92.9 mol% exhibited large hystereses in the phase-transition temperatures of their aqueous solutions. Isotactic-rich copolymers with NNPAAm compositions of 39.2–67.6 mol% exhibited large hystereses in the phase-transition temperatures of their aqueous solutions. Those of composition >67.6 mol% were insoluble in water. Stereosequence analysis suggested that isotactic sequences favored intramolecular hydrogen bonding between contiguous NNPAAm units, more than syndiotactic sequences. Enhanced intramolecular hydrogen bonding in isotactic sequences was responsible for the large hystereses and insolubility of isotactic-rich copolymers with high NNPAAm compositions.     

Poly(arylene ether sulfone) multi-block copolymers bearing perfluoroalkylsulfonic acid groups

Poly(arylene ether sulfone) (PAES) multi-block copolymers bearing perfluoroalkylsulfonic acid moieties were prepared from hydrophilic and hydrophobic prepolymers. The latter were synthesized by reaction of N,N-diisopropylethylammonium 2,2-bis(p-hydroxyphenyl)pentafluoropropanesulfonate (HPPS) with bis-(4-fluorophenyl) sulfone (FPS), and biphenol (BP) with FPS, respectively. Prepolymers and multi-block copolymers were prepared at 180 °C in N,N-dimethylacetamide in the presence of K₂CO₃. The prepolymers were reacted overnight; the multi-block copolymers were reacted only 80 min to minimize transetherification. Prepolymers and multi-block copolymers were characterized using ¹H and ¹³C NMR. ¹⁹F NMR provided molecular weight of hydrophilic prepolymers bearing aryl fluoride end groups. GPC was used to characterize the multi-block copolymers. Copolymer block lengths were determined by quantifying ¹³C NMR peak areas of quaternary carbon atoms adjacent to sulfur in FPS moieties. Hydrophilic and hydrophobic block lengths were in the range 9.4-23.4 and 4.4-11.8 repeating units, respectively. AFM showed phase separation for all block lengths. Conductivity at 80 °C and 100% relative humidity ranged from 6.2 to 34.3 mS/cm, with the best value obtained for hydrophilic/hydrophobic block lengths of 13.3/6.0.     

Synthesis and characterization of novel random copolyesters from trans-4-hydroxy-l-proline and functional cyclic esters

The melt polycondensation reaction of trans-4-hydroxy-N-benzyloxycarbonyl-l-proline (N-CBz-Hpr) and functional cyclic esters containing protected functional groups (carboxyl, and amino) at a wide range of molar fractions in the feed produced new degradable poly(N-CBz-Hpr-co-functional-ε-CL)s with stannous 2-ethylhexanoate (Sn(Oct)₂) as a catalyst. The optimal reaction conditions for the synthesis of the copolymers were obtained with 1.5 wt% Sn(Oct)₂ at 140 °C for 24 h. The copolymers obtained were characterized by Fourier transform infrared spectroscopy (FT-IR), ¹H NMR, differential scanning calorimetry, gel permeation chromatography, and Ubbelohde viscometry. The copolymers synthesized exhibited oligomeric molecular weights (3000-5000 g mol⁻¹) with modestly narrow molecular weight distributions (1.11-1.37). The values of the glass-transition temperature (T_g) of the copolymers depend on the compositions, and the molar fractions of cyclic lactone. For the poly(N-CBz-Hpr-co-4-EtC-ε-CL) system, with a decrease in 4-EtC-ε-CL contents from 79 to 3 mol%, the T_g increased from −34 to 67 °C In vitro degradation of these copolymers was evaluated from weight-loss measurements.     

Effects of chemical composition and stereoregularity on phase-transition behaviors of aqueous solutions of copolymers composed of N-isopropylacrylamide and N-n-propylacrylamide

Radical copolymerizations of N-isopropylacrylamide (NIPAAm) and N-n-propylacrylamide (NNPAAm) in various ratios were carried out in toluene at −40 °C in the presence of 3-methyl-3-pentanol to prepare syndiotactic copolymers with racemo dyad contents of ca. 70%. It was revealed that copolymers containing more than 92.5 mol% NNPAAm units exhibited large phase-transition hysteresis of their aqueous solutions. Sequence analysis suggested that intramolecular hydrogen-bonding of contiguous NNPAAm units in syndiotactic stereosequences in the dehydrated state were responsible for induction of the large hysteresis.     

Drug diffusion in hydrophobically modified N,N-dimethylacrylamide hydrogels

The use of hydrophobically modified hydrogels for drug release was investigated. Copolymers of N,N-dimethylacrylamide and 2-(N-ethyl-perfluorooctanesulfonamido) ethyl acrylate (FOSA) were prepared by free-radical polymerization. The drug release rates, dynamic swelling behavior, and pH sensitivities of copolymers ranging in composition from 0 to 30 mol% FOSA were studied. Pheniramine maleate, an ocular antihistamine, was used as the model drug substance. Hydrogels of DMA produced with increasing amounts of FOSA had a decreased equilibrium media content and exhibited a slower drug release rate. Early-time, late-time and Etters approximation drug diffusion coefficients ranged from 0.4×10⁻³ to 12.3×10⁻³ mm²/min. The diffusion of the drug model was less sensitive to pH of the buffered media over the range of pH 4-8, but increasing the media pH slowed the permeability slightly by decreasing the swellability of the hydrogel. The power law exponent (n≈0.5) and the swelling interface number (Sw?1) suggested that the drug release mechanism from these hydrogels was Fickian and not swelling controlled. These novel thermoprocessible hydrogels have potential to be used as controlled ocular drug delivery devices (e.g. contact lenses or ocular inserts).     

H NMR and C NMR investigations of sequence distribution and tacticity in poly(vinyl alcohol-co-vinyl levulinate)

The microstructure of poly(vinyl alcohol-co-vinyl levulinate) (VOH-VLA copolymer) was studied by ¹H NMR and ¹³C NMR techniques. The sequence distributions could be obtained from the six methine triads observed in the 500-MHz ¹H NMR spectra of the copolymers: the three methylene dyads and the three carbonyl triads observed in 125.6-MHz ¹³C NMR spectra of the copolymers. The reaction activity order of different tacticity hydroxyl in PVA was found to be rr > mr > mm by investigating VOH-centered methine tacticity triads. The vinyl levulinate content (VLC), the number-average sequence length, dyad-triad relation and triad-triad relation (R) were calculated from methine triads, methylene dyads and carbonyl triads in ¹H NMR and ¹³C NMR spectra successfully, and they were in good agreement with each other. The consistency of the dyad-triad and triad-triad relations shows that head to head or tail to tail fragments are hardly present in VOH-VLA copolymer.     

Thermo-, and pH dual-responsive poly(N-vinylimidazole): Preparation,characterization and its switchable catalytic activity

A monomer, 2-(isobutyramido)-3-methylbutyl methacrylate (IMMA) was synthesized through a two-step reaction. When a few of IMMA (less than 4 mol%) was copolymerized with N-vinylimidazole (VIm) under free radical polymerization condition, water-soluble P(VIm-co-IMMA) copolymers were obtained. Their structural information was verified and interpreted from ¹H NMR, FTIR and GPC. Kinetic analyses from ¹H NMR demonstrated that one-batch addition of IMMA into the polymerization system led to an inhomogeneous distribution of IMMA units in the copolymers, whereas homogeneous distribution of IMMA units in the copolymers could be obtained through the portion-wise addition of IMMA monomer. The thermal properties of such copolymers were measured by DSC. Compared with PVIm homopolymer, the few IMMA units in the P(VIm-co-IMMA) copolymer had little influence on the T_g values. The obtained P(VIm-co-IMMA) copolymers were thermoresponsive in water, and their phase transition temperatures could be efficiently raised through reducing the IMMA content in the copolymers, raising the addition times of IMMA monomers or lowering the pH of media. Dynamic light scattering analysis showed that unlike the traditional thermoresponsive linear polymers, obvious size shrinkage around the phase transition temperature could not be observed in such P(VIm-co-IMMA) copolymers. Such copolymers could be used as smart organocatalysts in the hydrolysis of p-nitrophenyl acetate. Below the phase transition temperature the reaction rate followed the Arrhenius law, but above the phase transition temperature the reaction rate increased much slower than the prediction from the Arrhenius law. Moreover, the catalytic transition temperature could be tuned through utilizing the P(VIm-co-IMMA) copolymers with different phase transition temperature. The mechanism was discussed accordingly.     

Synthesis, reactivity, and pH-responsive assembly of new double hydrophilic block copolymers of carboxymethyldextran and poly(ethylene glycol)

Double hydrophilic block copolymers (DHBC) were prepared by end-to-end coupling of two biocompatible water-soluble homopolymers: the polysaccharide dextran (M_w 8300 or 14,700 g mol⁻¹) and ω-amino poly(ethylene glycol) (PEG-NH₂, M_w 3000 or 7000 g mol⁻¹). The synthesis involved, first, specific oxidation of the dextran terminal aldehyde group and, second, covalent linkage of PEG-NH₂ via a lactone aminolysis reaction. The diblock copolymers dextran-PEG (DEX-PEG) were converted in high yield into the corresponding carboxymethyldextran-PEG (CMD-PEG) derivatives with control over the degree of substitution, from 30 to 85 mol% CH₂COOH groups per glucopyranosyl unit. Further modifications of a CMD-PEG block copolymer led to N-(2-aminoethyl)carbamidomethyldextran-PEG yielding a pair of oppositely-charged DHBC of identical charge density, chain length, and neutral block/charged block content. The properties of CMD-PEG in aqueous solutions were studied by static and dynamic light scattering as a function of solution pH, providing evidence of the pH-sensitive assembly of the copolymers driven by inter- and intra-chain hydrogen-bond formation.     

Formation of soluble hyperbranched polymer through the initiator-fragment incorporation radical copolymerization of ethylene glycol dimethacrylate with N-methylmethacrylamide

The copolymerization of ethylene glycol dimethacrylate (EGDMA) as a divinyl monomer with N-methylmethacrylamide (NMMAm) as a water-soluble monomer was carried out at 70 and 80 °C in N,N-dimethylformamide (DMF) using dimethyl 2,2′-azobisisobutyrate (MAIB) of high concentrations as initiator. When the concentrations of EGDMA, NMMAm and MAIB were 0.15, 0.50 and 0.35 mol/l, the copolymerization proceeded homogeneously with no gelation at 80 °C to give soluble copolymer in a yield of 50%. EGDMA was polymerized more rapidly than NMMAm as shown by Fourier-transform near infrared spectroscopy. The copolymer formed for 8 h consisted of 20 mol% of EGDMA unit, 47 mol% of NMMA unit and 33 mol% of methoxycarbonylpropyl group unit as MAIB-fragment. The copolymer formed at 80 °C for 30 min showed an upper critical solution temperature (34 °C on cooling) in methanol. The intrinsic viscosity of the copolymer formed for 2 h was very low (0.11 dl/g) at 30 °C in DMF despite high weight-average molecular weight [3.1×l0⁶ by multi-angle laser light scattering (MALLS)]. The copolymer exhibited a very low second virial coefficient (4.2×l0⁻⁶) as determined at 25 °C in DMF by MALLS. The individual copolymer molecules were observed as nanoparticles of 7-20 nm diameter by a transmission electron microscope. These results show that the resulting copolymers are of hyperbranched structure.     

Self-association and microenvironment of random amphiphilic copolymers of sodium N-acryloyl-l-valinate and N-dodecylacrylamide in aqueous solution

The present paper reports on the syntheses and association behavior of two random copolymers of sodium N-acryloyl-l-valinate and N-dodecylacrylamide in buffered (pH 8.0) aqueous solution containing 0.1 M NaCl. Surface tension and viscosity results showed pronounced amphiphilic nature of the copolymers in aqueous solution at pH 8.0. Steady-state fluorescence studies using pyrene and N-phenyl-1-naphthylamine as probe molecules suggested microdomain formation through interpolymer association above a critical concentration called ‘critical aggregation concentration’ (CAC) as low as ca. 10⁻³ g L⁻¹. The local polarity of the hydrophobic domain formed in aqueous solution was estimated from steady-state fluorescence spectra of pyrene. The microviscosity of the domains was evaluated using 1,6-diphenyl-1,3,5-hexatriene as a fluorescent probe using steady-sate fluorescence depolarization and time-resolved fluorescence method. Dynamic light scattering technique was performed over a wide range of concentration to determine hydrodynamic size of the aggregates. It was observed that both copolymers retain rather open conformation in dilute solutions having polymer concentrations less than CAC. However, with increase in concentration the intermolecular association becomes favorable towards the formation of more compact aggregates. The transmission electron microscopic images of both copolymers at a concentration above CAC revealed spherical aggregates of uniform diameter (∼50 nm).     

Synthesis and aqueous solution characterization of amphiphilic diblock copolymers containing carbazole

A series of near-monodisperse diblock copolymers of 2-(N-carbazolyl)ethyl methacrylate and 2-(dimethylamino)ethyl methacrylate (DMAEMA) of relatively low molecular weights (2600-24,000 g mol⁻¹) were synthesized by group transfer polymerization using tetrahydrofuran (THF) as a solvent. The molecular weight distributions and compositions of all the copolymers were obtained using gel permeation chromatography (GPC) in THF and proton nuclear magnetic resonance (¹H NMR) spectroscopy, respectively. Differential scanning calorimetry and thermal gravimetric analysis provided low glass transition temperatures (T_gs) of about 60 °C and decomposition temperatures between 320 and 450 °C for the copolymers, respectively. The three copolymers with the highest DMAEMA content were water-soluble below pH 7. Aqueous GPC at pH 3 showed that the water-soluble block copolymers formed micelles with apparent number average molecular weights above 100,000 g mol⁻¹.     

Synthesis of poly[dimethylsiloxane-block-oligo(ethylene glycol) methyl ether methacrylate]: an amphiphilic copolymer with a comb-like block

AB amphiphilic comb-like block copolymers of poly(oligo[ethylene glycol] methyl ether methacrylate) and polydimethylsiloxane were synthesised with a methodology based on atom transfer radical polymerization (ATRP). The anionic ring opening polymerisation of hexamethylcyclotrisiloxane followed by reaction with 3-(chlorodimethylsilyl) propyl 2-bromo-2-methylpropanoate propyldimethylchlorosilane gave suitable macroinitiators for the ATRP of oligo[ethylene glycol] methyl ether methacrylate. The latter synthetic procedure was optimised by performing a number of syntheses varying the reaction solvent, catalytic complex and the temperature used. Copolymers with relatively high polydispersity indices (M_w/M_n>1.3) could be synthesised at room temperature by employing a Cu(I)Br:N,N,N′,N′,N″-pentamethyldiethylenetriamine complex in n-propanol with Cu(II)Br. The optimum reaction conditions employed a Cu(I)Cl:N-(n-propyl)-2-pyridyl(methanimine) complex with an n-propanol/water mixture or toluene as solvent at 90 °C. This gave block copolymers of the desired molecular weights and polydispersity indices of less than 1.1. The block copolymers were characterised with ¹H NMR and ¹³C NMR spectroscopy and size exclusion chromatography.     

Micellization and phase transition behavior of thermosensitive poly(N-isopropylacrylamide)-poly(?-caprolactone)-poly(N-isopropylacrylamide) triblock copolymers

Thermosensitive triblock copolymers with two hydrophilic poly(N-isopropylacrylamide) blocks flanking a central hydrophobic poly(?-caprolactone) block were synthesized by atom transfer radical polymerization. Core-shell micellization of the triblock copolymers was inferred from the ¹H NMR spectra derived in two different solvent environments (CDCl₃ and D₂O). The micellar characteristics of these amphiphilic triblock copolymers were studied by pyrene fluorescence techniques, dynamic light scattering and transmission electron microscopy. The critical micelle concentrations of the triblock copolymers were in the range of 4-16 mg/L and the partition coefficients were in the range of 3.10 × 10⁴ to 2.46 × 10⁵. The mean diameters of the micelles, measured by light scattering, were between 90 and 120 nm. The temperature sensitivity of the triblock copolymers was demonstrated by the phase transition of a 250 mg/L aqueous polymer solution at the lower critical solution temperature (LCST). The enthalpy of the phase transition was determined by differential scanning calorimetry. PM3 quantum mechanical calculation method was used to understand the intermolecular interactions between the copolymer and the water molecules. A modular approach was used to simulate the phase transition observed at the LCST.     

Cocrystallization behavior of poly(hexamethylene terephthalate-co-hexamethylene 2,6-naphthalate) random copolymers

A series of poly(hexamethylene terephthalate-co-hexamethylene 2,6-naphthalate) (P(HT-co-HN)) random copolymers were synthesized by melt polycondensation and characterized using ¹H NMR spectroscopy and viscometry. Their cocrystallization behavior was investigated using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) method. Even though the P(HT-co-HN) copolymers synthesized are statistically random copolymers, they show a clear melting and a crystallization peak in DSC thermograms over the entire range of copolymer composition and have a minimum melting temperature in the plot of melting temperature versus copolymer composition. WAXD patterns of all the copolymer samples show sharp diffraction peaks and are largely divided into two groups, i.e. PHT type and PHN type crystals. In addition, WAXD patterns of the PHN type crystals are subdivided into two types of PHN α and PHN β according to the copolymer composition. These facts indicate that the P(HT-co-HN) copolymers show isodimorphic cocrystallization. The composition at which the crystal transition between PHT type and PHN type occurs is equivalent to the eutectic composition (22 mol% HN content) for the melting temperature. When the defect free energies were calculated by using the equilibrium inclusion model proposed by Wendling and Suter, the defect free energies in the case of incorporation of HT units in the PHN α and β crystals were higher than the case of incorporation of HN units in the PHT crystal lattice.     

Electrostatic self-assembly of thermally responsive zwitterionic poly(N-isopropylacrylamide) and poly(ethylene oxide) modified with ionic groups

The electrostatic self-assembly of thermally responsive copolymers of N-isopropylacrylamide (NIPAM) containing up to 10 mol% of the sulfobetaine monomer 3-[N-(3-methacrylamidopropyl)-N,N-dimethyl]ammoniopropane sulfonate) (SPP) and poly(ethylene oxide) modified with terminal cationic or anionic groups (IMPEO) was studied in methanol and aqueous solutions by static light scattering, turbidimetry, viscometry, and rheological measurements. The formation of graft-like complexes at stoichiometric dipole-ion ratio and their self-association was detected in the dilute and semidilute regime at temperatures below and above the lower critical solution temperature (LCST). The ability of the graft-like complexes to associate below the LCST depended on the sulfobetaine content of the copolymers, the functionality of IMPEO, and the polymer concentration. The effect of the IMPEO terminal group on the solution behavior of the graft-like complexes was less pronounced. With increasing temperature their semidilute aqueous solutions form gels, stable over a wide temperature range.     

Effect of the alkyl group on the synthesis and the electrochemical properties of N-alkyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquids

The effect of the alkyl side group on the synthesis and the electrochemical properties of N-alkyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR_1ATFSI) ionic liquids (ILs) is reported. The investigation was focused on the PYR_1ATFSI ionic liquid family because of the interesting electrochemical properties of the members with propyl and butyl side chains. Side alkyl groups (A = C_nH_2n+1 with n ranging from 1 to 10) of different length and structure were used for the synthesis of PYR_1ATFSI materials. NMR and DSC have shown that the ionic liquids were correctly synthesized with the exception of the compounds with tertiary side chains. Most of the materials exhibited a conductivity higher than 10⁻³ S cm⁻¹ already at 12 °C. In the molten state a moderate conductivity decrease was observed with increasing the length and the branching of the side chain (C₂H_2n+1) group according with the change of viscosity of the ionic liquids. Most of the PYR_1ATFSI samples exhibited an electrochemical stability window exceeding 5 V.