Structure formation and characterization of EVAL membranes with cosolvent of isopropanol and water

Microporous poly (ethylene-co-vinyl alcohol) (EVAL) membranes can be prepared by the solution casting method in combination of thermally induced phase separation (TIPS) with solvent evaporation. A cosolvent of isopropanol and water (3:2 w/w) is used to prepare the casting solution. EVAL membranes of different bulk or true densities, porosity, flexibility, crystallinity, and structure can be obtained by adjusting the casting temperature. A pseudo-binary temperature-concentration phase diagram of the EVAL-cosolvent system has been proposed, based on the information obtained from SEM, DSC, and light transmittance studies, to account for the membrane formation mechanism. The dense membranes were obtained when the casting temperature was higher than the upper critical solution temperature (UCST) of the system, but they might contain some nonSEM-observable micropores if the casting temperature was below the glass transition temperature (T_g) of EVAL. The porous and the least crystalline membranes with a honeycomb-like morphology were obtained through liquid-liquid demixing and vitrification at a casting temperature between the UCST and the dynamic crystallization temperature (T_c). Highly porous and crystalline membranes were obtained when they were prepared at temperatures near T_c. In this case, the particulate membranes were resulted from solid-liquid demixing mainly via TIPS, and membranes with leafy morphology were created through liquid-liquid demixing and then followed with immediately crystallization.     

Formation of poly‐vinyl‐alcohol structures by supercritical CO2

Poly‐vinyl‐alcohol (PVA) porous structures have been prepared using a supercritical phase inversion process in which supercritical carbon dioxide (SC‐CO₂) acts as the nonsolvent. First, we tested the versatility of the SC‐CO₂ phase inversion process, forming PVA/dimethylsulfoxide (DMSO) solutions with polymer concentrations ranging from 1 to 35% (w/w) and changing the process parameters. We worked at temperatures from 35 to 55°C and pressures from 100 to 200 bar obtaining different membranes morphologies: dense films, membranes with coexisting morphologies, and microparticles. However, we did not produce symmetric or asymmetric porous membranes. To obtain this result, we used casting solutions formed by adding acetone to DMSO with the aim of modifying the affinity between SC‐CO₂ and the liquid solvent. In this series of experiments, we obtained asymmetric membranes with skin layer thicknesses lower than 10 μm. The results obtained in this work have been explained considering that the membranes formation mechanism is related to the kinetics of the process; i.e. the affinity between the solvent (mixture of solvents) and SC‐CO₂. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Pore morphology control and hydrophilicity of polyacrylonitrile ultrafiltration membranes

The effects of different solvents (dimethyl formamide: DMF and dimethylsulfoxide: DMSO) on the solubility of polyacrylonitrile (PAN) were investigated by the phase diagrams of H₂O/DMF/PAN and H₂O/DMSO/PAN ternary systems through cloud‐point titration method at low polymer concentration. The influences of polymer concentrations and temperatures on the morphologies of PAN ultrafiltration membranes were elucidated. The morphologies of fabricated UF membranes were characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM), and the basic performance of ultrafiltration including pure water flux and rejection of BSA were explored. At 25°C, the pure water flux of ultrafiltration membranes at the lower PAN content (16 wt % PAN in 84 wt % DMSO) reached 213.8 L/m/bar and the rejection of BSA was 100%. Interestingly, the water flux of UF membranes dramatically decreased to 20.6 L/m/bar (20 wt %) and 2.9 L/m/bar (24 wt %) when increasing PAN concentrations in DMSO. On the other hand, the hydrophilicity of membranes can be enhanced by increasing coagulation temperatures and polymer concentrations which were characterized by static contact angle, fitting well with the variation tendency of roughness. Although there are many works concerning on the effects of phase inversion conditions on the performance of PAN UF membranes, to our best knowledge, there is seldom works focusing on investigating the membrane hydrophilicity trend by adjusting phase inversion conditions. To disclose the reason of the enhanced hydrophilicity, the water and glycol contact angles of various membranes were measured and the surface tensions were presented. The results illustrated that the enhanced hydrophilicity of PAN UF membranes fabricated at higher temperatures or higher polymer concentrations was due to the higher polarity on membrane surface. Since the vast majority of ultrafiltration membranes in labs and in industrial scale have been fabricated by immersion phase inversion method, this work can provide a guidance to obtain hydrophilic PAN UF membranes by adjusting the process of phase inversion. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41991.     

Binary blends based on poly(N‐isopropylacrylamide): Miscibility studies with PVA,PVP, and PAA

Blends of poly(vinyl alcohol) (PVA), poly(acrylic acid), (PAA), and poly(vinyl pyrrolidone) (PVP), with poly(N‐isopropylacrylamide) (PNIPAM), were prepared by casting from aqueous solutions. Mechanical properties of PNIPAM/PVA blends were analyzed by stress–strain tests. Differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were employed to analyze the miscibility between the polymeric pairs. The results revealed that PNIPAM is not miscible with PVA and PVP in the whole range of composition. On the other hand, PNIPAM interacts strongly with PAA forming interpolymer complex due to the formation of cooperative hydrogen bonds. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 743–748, 2004     

An approach to the development of cellulose acetate ultrafiltration membranes

The film-casting solution consisted of a mixture of cellulose acetate, acetone, and aqueous magnesium perchlorate [Mg(ClO₄)₂:H₂O = 1:8.5], designated as polymer P, solvent S, and nonsolvent N, respectively. Using the composition P:S:N = 17: 69.2: 13.8 as reference, films were obtained from 19 different casting solutions in which the weight ratios S/P, N/S, and N/P were varied in different directions. The casting solution temperature was 0°C, and solvent evaporation period during film formation was minimum in most cases. The effects of variations of casting solution temperature and solvent evaporation period were also briefly studied. Reverse osmosis experiments with resulting membranes were carried out at 100 psig using 200 ppm NaCl–H₂O as the feed solution. Decrease in S/P, increase in N/S, and increase in N/P in the casting solution, decrease in temperature of the casting solution, and increase in solvent evaporation period tend to increase the size of pores on the surface of resulting membranes in the ascast condition. Increase in S/P in the casting solution, and increase in the temperature of the casting solution tend to increase the effective number of pores on the membrane surface. These results offer definitive physicochemical criteria in terms on solution structure–evaporation rate concept for developing useful cellulose acetate ultrafiltration membranes.     

Effects of cononsolvency on preferential adsorption phenomenon in poly(N‐isopropylacrylamide) ternary solutions

In this work, the effect of cononsolvency on the phase transition and preferential adsorption phenomenon behaviors of poly(N‐isopropylacrylamide)/methanol/water ternary solutions was studied. In this cononsolvent system, the , , and χ₁₂ values show a nonlinear behavior and the minimum values of and , while the maximum value of χ₁₂ at ϕ₂ is around 0.7. These facts indicated that one water molecule could directly bond with one methanol molecule to form the H₂O MeOH complex. The H₂O MeOH complex structure was found to remarkably affect the phase transition of poly(N‐isopropylacrylamide) (PNIPAM) in ternary solution. However, at the composition of mixed cononsolvent, ϕ₂ < 0.2, the PNIPAM molecules may preferentially adsorbed pure water molecules; therefore, the LCST decreases slightly with composition of mixed cosolvent and this may be because of the small amount of H₂O MeOH complexes in the mixed cononsolvent. While, at ϕ₂ > 0.7, the PNIPAM molecules may preferentially adsorbed pure methanol molecules. PNIPAM ternary solutions were transparent and no transition occurred in this region. This indicates that the PNIPAM coils exhibited a much‐extended conformation in solutions. In contrast, at 0.2 < ϕ₂ < 0.4 and 0.4 < ϕ₂ < 0.7, PNIPAM molecules preferentially adsorbed water and methanol molecules, respectively, and also adsorbed large amount of H₂O MeOH complexes. In these regions, the clathrate‐like structure around the side chain of PNIPAM molecule became more defected with adsorbing H₂O MeOH complex. Therefore, we considered that the various thermodynamic behaviors between PNIPAM and mixture solvents must be related different preferential adsorption phenomena, which were mainly related to different degrees of polymer–solvent interaction and structures of solvent used. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Improvement of porous cellulose acetate reverse osmosis membranes by change of casting conditions

The effects of temperature of casting solution in the range ?10° to 15°C, that of casting atmosphere in the range 10° to 30°C, relative humidity of casting atmosphere in the range 35% to 75%, and solvent evaporation period in the range 0.5 to 3 min were studied on shrinkage temperatures, solute separations, and product rates of Loeb-Sourirajan-type cellulose acetate membranes in reverse osmosis experiments. The composition of casting solution used was as follows: cellulose acetate, 17; acetone, 69.2; magnesium perchlorate, 1.45; and water, 12.35 wt-%. Best performance was obtained with membranes cast under the following conditions: temperature of casting solution, 10°C; temperature of casting atmosphere, 30°C; relative humidity of casting atmosphere, 65%; and solvent evaporation period, 1 min. For a 90% level of solute separation, the productivities of the above type of membranes were 22.9, 61.4, and 64.5 gallons/day-ft² at 250, 600, and 1500 psig using 3500 ppm NaCl–H₂O, 5000 ppm NaCl–H₂O, and 28395 ppm NaCl–H₂O feed solutions, respectively. In all cases, the feed flow rates corresponded to a mass transfer coefficient of 45 × 10^?4 cm/sec on the high-pressure side of the membrane. The general specifications of the above type of membranes are given for the operating pressures of 250, 600, and 1500 psig. The effects of the above casting condition variables on the surface pore structure during film formation are discussed.     

Constant rotational rheological behaviors of the PAN/DMSO/nonsolvent systems

The constant rotational rheological behaviors of PAN/DMSO solutions with two kinds of nonsolvent (water and ethanol) have been investigated, respectively, using a cone‐plate rheometer. From viscosity measurements, the flow behavior was described within the shear rate range 0.1–1000 s^?1. The PAN solutions show shear thinning at high shear rates. The viscosities of the solutions decreased with the rising of the temperature at low shear rate. H₂O content has great influence on the viscosity of the solutions, depending on the hydration of H₂O and PAN or desolvent effect, according to different H₂O content. The role of ethanol compared with H₂O was also researched and higher viscosity was found. Non‐Newtonian index, structural viscosity index Δη, and flow activation energy of the PAN/DMSO/H₂O systems were also studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Evidences of solvent‐induced miscibility in polychloroprene‐co‐ethylene‐propene diene terpolymer blends

Solvent dependent changes in the compatibility behavior of Polychloroprene/Ethylene–propylene–diene terpolymer blends (CR/EPDM) have been investigated using dilute solution viscometry and solvent permeability analysis. To predict the compatibility of rubber blends of different compositions in solvents of different cohesive energy densities, Huggins interaction parameter (ΔB), hydrodynamic interaction (Δη) and Sun's parameter (α) were evaluated from the analysis of the specific and reduced viscosity data of two and three‐component polymer solutions. Miscibility criteria were not satisfied for CR/EPDM blends over the entire composition range in toluene, xylene, and carbon tetrachloride (CCl₄), however, a narrow miscibility domain was observed in chloroform (CHCl₃) for CR/EPDM/CHCl₃ system. These results were further corroborated with the analysis of heat of mixing (ΔH_m) and polymer–polymer interaction parameter (χ₁₂), for all rubber blend compositions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The influence of solvent properties on the performance of polysulfone/β‐cyclodextrin polyurethane mixed‐matrix membranes

This study investigates the effect of solvent properties on the structural morphology and permeation properties of polysulfone/β‐cyclodextrin polyurethane (PSf/β‐CDPU) mixed‐matrix membranes (MMMs). The membranes were prepared by a modified phase‐inversion route using four different casting solvents [dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), dimethyl acetamide (DMA), and N‐methyl‐2‐pyrrolidone (NMP)]. While DMSO‐based membranes demonstrated particularly high permeability (ca 147 L/m²h.bar), their crystallinity was low compared to MMMs prepared using DMA, DMF and NMP due to the formation of thin active layers on their surfaces. Cross‐sectional morphology revealed that the MMMs have a dense top skin with finger‐like inner pore structures. Membranes prepared using NMP displayed the highest hydrophilicity, porosity, and crystallinity due to the low volatility of NMP; DMF membranes exhibited superior mechanical and thermal stability due to its (DMF) high hydrogen bonding (δH) values. Thus, the morphological parameters, bulk porosity, and flux performance of MMMs have a significant inter‐relationship with the solubility properties of each solvent (i.e., δH, density, volatility, solubility parameter). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2005–2014, 2013     

Hemodialysis membrane prepared from cellulose/N‐methylmorpholine‐N‐oxide solution. II. Comparative studies on the permeation characteristics of membranes prepared from N‐methylmorpholine‐N‐oxide and cuprammonium solutions

Two kinds of regenerated cellulose membranes for hemodialysis were prepared from casting solutions of N‐methylmorpholine‐N‐oxide (NMMO) and cuprammonium (denoted NMMO membranes and cuprammonium membranes, respectively). The concentration of cellulose in the casting solution investigated was 6–8 wt %. The permeation characteristics of both membrane series were compared in terms of the ultrafiltration rate (UFR) of pure water, the sieving coefficient (SC) of dextran, and the solute permeabilities of urea, creatinine, and vitamin B₁₂. The UFR and SC of the NMMO membranes were strongly affected by the cellulose concentration of the casting solution, and NMMO was a preferable solvent for the production of cellulose membranes with high performance; the cuprammonium solution gave low‐performance membranes. The pore structures of both types of membranes were estimated with the Hagen–Poiseuille law. The results showed that the NMMO membranes had larger pore radius and smaller pore numbers than the cuprammonium membranes. The differences in the membrane pore structures led to the differences in the performance between the two membrane series. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 333–339, 2003     

Preparation and characterization of polyacrylonitrile-based membranes: Effects of internal coagulant on poly(acrylonitrileco-malefic acid) ultrafiltration hollow fiber membranes

Ultrafiltration hollow-fiber membranes (UHFMs) ofpoly(acrylonitrile-co-malefic acid) (PANCMA) were prepared by a dry-wet phase inversion process. The morphologies of inner surface and cross section for these hollow fibers were inspected with scanning electron microscopy. It was found that, by increasing the amount of solvent DMSO in internal coagulant, the number and size of macrovoid underneath the inner surface decreased. The water flux of the UHFMs also decreased while the bovine serum albumin rejection increased minutely. These results were interpreted based on the ternary phase diagrams for the PANCMA/DMSO/(H₂O+DMSO) system, which was obtained from the experimental cloud point measurements and empirical linearized cloud point relation. It was envisaged that the membrane surface could be further modified by the reaction of acid groups with poly(ethylene glycol).     

Synthesis of sulfoxide-modified ethylene—vinyl alcohol copolymers for the permselective membrane of sulfur dioxide

The Michael-type addition reaction of ethylene-vinyl alcohol copolymer (EVAL) with a series of vinyl sulfoxides namely methyl, ethyl, t-butyl and phenyl vinyl sulfoxides, was performed with NaOH as a catalyst in DMSO solution to produce 2-(alkyl or phenyl sulfinyl)ethyl EVAL derivatives. The high perm-selectivity of sulfur dioxide against nitrogen was achieved through these sulfoxide-modified EVAL membranes.     

Gas permeation of polymer blends. IV. Poly(vinyl chloride) (PVC)/acrylonitrile–butadiene–styrene (ABS) terpolymer

The transport behavior of He, O₂, N₂, and CO₂ in membranes of poly(vinyl chloride) (PVC)/acrylonitrile–butadiene–styrene (ABS) blends has been studied at 25°C. The blends were further characterized by dynamic mechanical measurements, differential thermal analysis (DTA), density measurements, and x-ray diffraction. The equilibrium sorption of CO₂ and N₂ was measured directly at atmospheric pressure using an electromicrobalance and compared with sorption values obtained as P/D ratios from permeation measurements. The rates of permeation (P) and diffusion (D) increase with increasing ABS content in the blends. The P and D values are not additive, and only slight indications of phase inversion in the blends are observed at 5–10 wt-% ABS in the blends. Experimental densities of the blends are higher than calculated densities assuming volume additivity. The data are interpreted to mean that the PVC/ABS blends form a two-phase system composed of a soft polybutadiene (rubber) phase and a rigid PVC/styrene–acrylonitrile copolymer (SAN) phase of mutually compatible components. DTA and dynamic mechanical measurements also show a two-phase system. Sorption values of CO₂ and N₂ by equilibrium sorption measurements increase with increasing ABS content in the blends without the large fluctuations which have been observed for the sorption values obtained from the time lag method. Comparison of the two types of sorption values (from direct measurements and from P/D ratios) show larger deviations for CO₂ than for N₂. This suggests that the time lag method is not valid for permeants with polar character in heterogeneous two-phase systems where chemical immobilizing effect on the permeant molecules occurs.     

Thermal,Spectroscopic, and Mechanical Properties of Blend Films of Poly(N-Vinyl-2-Pyrrolidone) and Sodium Alginate

Blends of poly(N-vinyl-2-pyrrolidone) (PVP) and sodium alginate (NaAlg) were prepared by casting from aqueous solutions. These blends were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and tensile strength test. The miscibility in the blends of PVP and NaAlg was established on the basis of the thermal analysis results. DSC showed that the blends possessed single, composition-dependent glass transition temperatures (T _g s), indicating that the blends are miscible in amorphous state. FT-IR studies indicate that there are the intermolecular hydrogen bonding interactions, i.e., –OH·····O=C in PVP/NaAlg blends. This blend films also exhibited the higher thermal stability and improved the elongation at break in dry states.     

Kinetics of diffusion in polyacrylonitrile fiber formation

A H₂O/dimethyl sulfoxide (DMSO) mixture was used as the coagulation bath of the wet‐spun process for polyacrylonitrile fibers. Diffusion behaviors of coagulate and solvent of the protofibers were studied. Diffusion coefficients of H₂O and DMSO of the protofibers, prepared by acrylonitrile (AN) homopolymers, were also determined. It was found that diffusion coefficients of H₂O and DMSO in the protofibers prepared by AN homopolymers, synthesized by DMSO solution polymerization, are highest compared with those of AN homopolymers synthesized by H₂O/DMSO mixture suspension polymerization and aqueous suspension polymerization. With increasing polyacrylonitrile concentration in the dope, diffusion coefficients of H₂O and DMSO decreased continuously. Diffusion coefficients of H₂O and DMSO increased concomitantly with increasing bath temperature, but the changes of diffusion coefficient values were less prominent when the temperature increased beyond 60°C. When DMSO concentration in the coagulation bath was 55 wt %, the values of diffusion coefficients of H₂O and DMSO were minimal. Diffusion coefficients increased with increasing jet stretch minus ratio. When the protofiber radius was increased, there was a corresponding increase of diffusion coefficients of H₂O and DMSO. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1529–1533, 2005     

Morphology and properties of cellulose/chitin blends membranes from NaOH/thiourea aqueous solution

Blend membranes of chitin/cellulose from 12 : 50 to 12 : 250 were successfully prepared from cotton linters in 1.5M NaOH/0.65M thirourea solution system. Two coagulation systems were used to compare with each other, one coagulating by 5 wt % H₂SO₄ (system H), and the other by 5 wt % CaCl₂ and then 5 wt % H₂SO₄ (system C). The morphology, crystallinity, thermal stabilities, and mechanical properties of the blend membranes were investigated by electron scanning microscopy, atomic absorption spectrophotometer, infrared spectroscope, elemental analysis, X‐ray diffraction, different scanning calorimeter, and tensile tests. The cellulose/chitin blends exhibited a certain level of miscibility in the weight ratios tested. There were great differences between the two blends H coagulated with H₂SO₄ and C coagulated with CaCl₂ and H₂SO₄, respectively. The membranes H have a denser structure, higher thermal stability, tensile strength (σ_b), and crystallinity (χ_c), and values of σ_b (90 MPa for chitin/cellulose 12 : 150) were significantly superior to that of both chitin and regenerated cellulose membrane. However, the blend membranes C have much better breaking elongations (?) than that of membranes H, and relatively large pore size (2r_e = 210 μm), owing to the removal of a water‐soluble calcium complex of chitin as pore former from the membranes C. When the percentage content of chitin in the blends was from 5 to 7.5%, the values of breaking elongation for the blend membranes H and C all were higher than that of unblend membranes, respectively. The blends provide a promising way for application of chitin as a functional film or fiber in wet and dry states without derivates. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2025–2032, 2002     

Process and fiber spinning studies for the cellulose/paraformaldehyde/dimethyl sulfoxide system

A cellulose pulp of about 550 D.P. was readily dissolved in a combination of (CH₂O)x/DMSO to afford an initial 6/6/88 cellulose/(CH₂O)x/DMSO composition solution. The concentration of formaldehyde was found to be a function of solution heating time and temperature. The solutions were microscopically free of gels and undissolved cellulose fibers. Cellulosic articles such as fibers and films are easily regenerated from these cellulose solutions in the presence of coagulants such as methanol or water. Fibers with high wet modulus, intermediate tenacity, and low elongations were produced from these regenerations systems. Fibers have been spun with conditioned and wet tenacities as high as 2.9 and 2.1 g/d, respectively, with wet modulus (at 5% elongation) as high as 1.3 g/d and solubility in 6.5% NaOH in the low range of 3.0%–15%. In many respects, these fibers are comparable to those produced in the viscose process. However, the low elongations of these fibers probably would not permit normal textile processing. The cellulose/(CH₂O)x/DMSO solutions were modified with compounds containing reactive N? H functional groups which are known to react with excess formaldehyde to yield the corresponding N-methylol derivatives. However, the resulting fiber physical properties were not significantly improved compared to those obtained from unmodified cellulose solutions. Addition of acrylic acid derivatives such as methyl acrylate, butyl methacrylate, or acrylonitrile to the cellulose solutions did not result in the formation of the expected 1,4-type adducts.     

Physical and electrochemical characterizations of poly(vinylidene fluoride‐co‐hexafluoropropylene)/SiO2‐based polymer electrolytes prepared by the phase‐inversion technique

Highly porous poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVdF–HFP)‐based polymer membranes filled with fumed silica (SiO₂) were prepared by a phase‐inversion technique, and films were also cast by a conventional casting method for comparison. N‐Methyl‐2‐pyrrolidone as a solvent was used to dissolve the polymer and to make the slurry with SiO₂. Phase inversion occurred just after the impregnation of the applied slurry on a glass plate into flowing water as a nonsolvent, and then a highly porous structure developed by mutual diffusion between the solvent and nonsolvent components. The PVdF–HFP/SiO₂ cast films and phase‐inversion membranes were then characterized by an examination of the morphology, thermal and crystalline properties, absorption ability of an electrolyte solution, ionic conductivity, electrochemical stability, and interfacial resistance with a lithium electrode. LiPF₆ (1M) dissolved in a liquid mixture of ethylene carbonate and dimethyl carbonate (1:1 w/w) was used as the electrolyte solution. Through these characterizations, the phase‐inversion polymer electrolytes were proved to be superior to the cast‐film electrolytes for application to rechargeable lithium batteries. In particular, phase‐inversion PVdF–HFP/SiO₂ (30–40 wt %) electrolytes could be recommended to have optimum properties for the application. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 140–148, 2006     

FTIR microspectroscopy and DSC analysis of blends of poly(vinylidene fluoride) with isotactic and syndiotactic poly(methyl methacrylate)

Films of blends of poly(vinylidene fluoride) (PVDF) with isotactic and syndiotactic poly(methyl methacrylate) (i-PMMA and s-PMMA), obtained by casting tetrahydrofuran (THF) and dimethyl sulphoxide (DMSO) solutions onto BaF₂ windows, have been investigated by means of FTIR-microspectroscopy (FTIR-M), optical microscopy and differential scanning calorimetry (DSC). The study of the effect of the PMMA tacticity on the intermolecular interaction between the two components, as well as on the structure, morphology and thermal behaviour of these blends, is the object of this paper. On the basis of the major shift of the carbonyl band of i-PMMA in the mixtures, the occurrence of stronger interactions for PVDF/i-PMMA compared with PVDF/s-PMMA blends can be suggested. © 1998 SCI.