Coelho, D.

Sampaio, A.

Santos, C.

Silva, C.

Zille, Andrea

Universidade do Minho: RepositoriUM

A.Sampaio¹*, C.Santos¹, C.Silva¹, D.Coelho¹, A. Zille² | ¹ CeNTI - Centro de Nanotecnologia e Materiais Técnicos, Funcionais e Inteligentes, Rua Fernando Mesquita 2785, 4760-034 V. N. Famalicão, Portugal | ² 2C2T – Centro de Ciência e Tecnologia Têxtil, Departamento de Engenharia Têxtil, Universidade do Minho, Campus de Azurém, 4800-058 Guimarães, Portugal | *asampaio@centi.ptwww.centi.ptPreparation and characterization of polysaccharides/PVA blend nanofibrous membranes prepared by ElectrospinningIntroductionElectrospinning allows the production of polymer fibres with diameters in the sub-micron size range, through the application of an external electric field, keeping intact the bulk properties of the polymers (fig.1). Electrospun membranes possess some unique structural features, such as a high surface to volume ratio and very good mechanical performance, properties that are determinant to their use in several applications such as air and liquid filtration, tissue engineering, optical and chemical sensors [1].Main GoalElectrospinning of a blend containing biopolysaccharides (chitosan and exopolysaccharides) and polyvinyl alcohol (PVA) into a polyvinylidene difluoride (PVDF) basal microfiltration membrane, with the ultimate aim of developing a mid-layer nanofibrous porous support for exploitable thin-film composite (TFC) membranes for water filtration.The electrospun blended nanofibrous membranes were fully characterized in order to investigate their morphology, diameter, structure, mechanical and thermal properties. The results showed that these membranes have great potential for filtration purposes [2].fig.1 - electrospinning equipmentExperimentalPVDF - basal filter5 cm  Ø | 0.2 µmPolymer solutions Electrospinninga) PVA 12%wt (in H2O) | b) PVA 12%wt + Chitosan (CS) 0.5%wt (in 1% Acetic acid aq. solution) | c) PVA 12%wt + cyanobacterial extracellular polymeric substances (EPS) 0.5%wt (50/50 DMSO:H O)ConditionsRoom temperature | 10mL syringe with needles of 0.5mm of inner diameter | Electric field: 20  to 23k | Feed rate: 0.2mL/helectrospinning process+ DC HighVoltagepolymer solutionEPolymer blend (%wt) Conductivity (µS cm¯¹) Viscosity (cP)12% PVA12% PVA ± 0.5% EPS12% PVA ± 0.5% CS874±91149±261274±2096±3563±3442±12Resultsa b cSEM AFM (analysis area - 5x5 µm) fig.2 - SEM and AFM images of PVA/polysaccharide blended electrospun fibres using (a) 12%wt PVA, (b) 12%PVA and 0.5%CS,  and (c), 12%PVA and 0.5%EPS solutions. CONSTotalPVAElementPVA/CS PVA/EPSWt % At % Wt % At % Wt % At %44.30 51.44 42.27 49.26 37.32 44.2555.70 48.56 55.84 48.85 61.97 55.401.89 1.890.71 0.35100.00 100.00 100.00 100.00 100.00 100.00- -- -- -- -Conclusions- Electrospun PVA/CS and PVA/EPS blend nanofibrous mem-branes were successfully prepared, with an uniform and smooth morphology, and narrow diameter distribution from ≈50 to 130nm.- Thermal and mechanical analysis demonstrated the pres-ence of intermolecular hydrogen bonds between the polysac-charides and PVA. - The electrospun PVA/polysaccharides blended membranes showed better tensile mechanical properties when compared with PVA alone, and resisted more against disintegration in the temperature range between 10 and 50 °C. - These membranes were afterwards further coated with an ul-tra-thin selective top layer. table 1 -  Variation of weight and atomic percentages of the atoms C, O, N and S in the electro-spun nanofibresfig.3 - Tan δ curves versus temperature of the mem-branes. PVDF (solid grey line), PVDF coated with PVA nanofibres (dashed grey line), PVDF coated with PVA/CS nanofibres (dashed black line), and PVDF coated with PVA/EPS nanofibres (solid black line).References[1] Liu, Y., Wang, R., Ma, H. Y., Hsiao, B. S., Chu, B. (2013) High-flux microfiltration filters based on electrospun polyvinylalcohol nanofibrous membranes. Poly-mer, 54, 548-556. | [2] Santos, C., Silva, C. J., Büttel, Z., Guimarães, R., Pereira, S. B., Tamagnini, P., Zille, A. (2014) Preparation and characterization of polysac-charides/PVA blend nanofibrous membranes by electrospinning method. Carbohydrate Polymers, 99, 584-592AcknowlegdementsThis work was funded by FEDER funds through the Operational Competitiveness Programme – COMPETE and by National Funds through FCT – Fundação para a Ciência e a Tecnologia under the project FCOMP-01-0124-FEDER-009389 (PTDC/CTM/100627/2008).Preparation of electrospun blend nanofibrous membranes > Characterization of electrospun PVA/polysaccharides blend membranes:  AFM, SEM, EDS, DMA.DMAViscosity and conductivity of the polymer solutions²

Preparation and characterization of polysaccharides/PVA blend nanofibrous membranes prepared by Electrospinning

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