Single‐wall carbon nanotubes‐chitosan nanocomposites: Surface wettability, mechanical and thermal properties

Functionalized single-wall carbon nanotubes (f-SWCN) are dispersed in chitosan films by self-assembly of both components aqueous media. This form is a promising nanofiller to achieve nanocomposites with refined thermal, mechanical and surface features. In this study, we investigated the influence functionalized concentration on resulting properties structures. molecular scale polymeric matrix due electrostatic interactions between components. The thermal have been characterized thermogravimetric analysis dynamic analysis, respectively, while their wettability studied water contact angle measurements. Mechanical resistance improved up 18 % addition nanotubes, but stability expressively reduced. A decrease hydrophobicity 25 obtained after inclusion nanofiller. Funktionalisierte Einwand-Kohlenstoffnanoröhren (f-SCWN) bilden mit Chitosan-Filmen eine Dispersion wässrigen Lösungen. Diese Form des Kohlenstoffs ist ein vielversprechender Kandidat für Nanokomposite verbesserten Oberflächen-, thermodynamischen und mechanischen Eigenschaften. dieser Studie wurde der Einfluss funktionalisierten Einwand-Kohlenstoffnanoröhren-Konzentrationen auf die resultierenden Eigenschaften Nanokomposit-Strukturen untersucht. Aufgrund elektrostatischen Kräfte zwischen dem Chitosan-Film den werden letztere Polymer-Matrix molekularen Level gelöst. Die thermischen wurden mittels thermogravimetrischer dynamischer mechanischer Analysen untersucht, wohingegen Benetzbarkeit Oberfläche Kontaktwinkel-Untersuchungen ermittelt wurde. Der mechanische Widerstand Filme wird durch Zugabe von um bis zu verbessert, thermische Stabilität jedoch stark verringert. Nach Einschluss Nanofüllstoffes Abnahme Oberflächenhydrophobie beobachtet. use biopolymers has attracted significant interest development composite as they derived from renewable sources including carbohydrates proteins plant or animal origin 1. Chitosan one most interesting natural sources. Some prominent antibacterial antifungal activity, non-toxicity, biocompatibility, biodegradability solubility acidic solutions. acid media contributes its processability into different forms, like scaffolds, gels, nanofibers, nanoparticles films, which enables wide range applications 2, 3. normally processed gels since last decade, studies concerning biopolymer materials increased equating number those traditional 4, 5. excellent film-forming property allows production using solvent evaporation method. However, brittle moderated 6, 7. Many strategies were explored improve chitosan-based such crosslink chains association calcium phosphate cement, hydroxyapatite, clays others produce composites 1, Bionanocomposites proposed an alternative for conventional technologies biopolymers-based materials, also outperform other polymer intrinsic limitations, content gas permeability. They hybrid composed reinforced fillers nanometer range, nanoparticles, nanosheets halloysite 8, 9. These nanofillers usually added small concentrations, 5 relation polymer, large aspect ratio these structures multiple main requirement homogeneous dispersion maximal enhancement 10. Among various employed, (CN) some whose further recent years. Carbon presents cylindrical structure formed winding graphene sheets tubes nanometers diameter not only electrical, antimicrobial matrices. When single-cylinder, nanotube called single-walled (SWCN) 11, 12. To prevent agglomerations allow good within complexation can be considered. improvement achieved strong intermolecular forces reach essential interfacial bonding 13. reinforcement effect must maximized without aggregation matrix. ultrasound and/or high-speed stirring convenient easy methods nanofillers. addition, chemically modified insertion active chemical groups compatible hydrophilic carboxylic interact protonated amino leading at nanoscale level, preventing tendency agglomeration. hydrogen bond interaction COOH NH2 atomic level was demonstrated dynamics simulation 14. Polymeric produced (CHI) combine obtain new characteristics that arduous individually 2. reported multi-walled (MWCN) showing homogeneously 7, 15. Changes depend compatibility concentration, method used prepare conditions defined (pH relative humidity, example) 4. chosen nanocomposite films. wettability, mechanical, structural investigated. our laboratory following earlier described process, includes demineralization, deacetylation deproteinization squid pens 16. average weight (400 kDa) degree acetylation (9 %) determined viscometry conductometric titration, previously 17, 18. Single-walled (SWCN), purchased Sigma Aldrich. 1 solution prepared dissolution acetic (1 %, v/v). After that, 0.10 mg, 0.25 mg 0.50 10 g solution. Sonication homogenizer employed guarantee proper dispersion. mixtures poured teflon molds (11×1 cm) dried air flux technique until thin easily removed supports. Films labeled CHCN10, CHCN25 CHCN50 regarding concentration. control film same procedure. stored humidity-controlled chamber (65 %). thickness measured micrometer (Model M110-25, Mitutoyo MFG. Co. Ltd., Japan). Thickness measurements taken points along mean values calculated Scanning electronic microscopy (SEM) carried out ZEISS LEO-440 microscope (Cambridge, England) OXFORD (model 7060) LEO 440 detector accelerating voltage 20 keV. Samples cm×1 cm coated 6 nm gold layer. Contact CAM 200 equipment (KSV Instruments – Helsinki, Finland). 3 μL deionized dropped onto acquisition images 30 s drop equilibration. value represents least five independent Fourier-transform infrared spectroscopy (FTIR) performed casting diluted spectrum KBr pellet. Spectra Shimadzu IR Affinity-1 4000 cm−1–400 cm−1 interval 4 resolution. Thermogravimetry (TG) analyzer Q50 (TA Instruments, USA) measure loss under heating. (10 mg) heated alumina crucible °C 800 min−1 synthetic atmosphere (90 mL min−1). extrapolated onset temperature (Tonset) software TA Universal Analysis. Q800 operating tension clamp force rate N distance clamps mm. For each sample, strips (6.3 mm×15 mm) tested tensile strength elongation break determined, point maximum stress curve strain when ruptures. Differences analyzed variance (ANOVA) followed Tukey's test. significance set %. combination nanodimension, composition results superior nanocomposites. Even though versatile dispersibility solvents limitation explore use. Chemical functionalization very effective improves order maximize effects disperse it matrix, access chains. observed sonication processes necessary final solutions even days, any precipitate agglomerate. Furthermore, higher amount darker color noticed, confirming well dispersed. At macroscopic scale, grayer increasing visualized all them homogeneous, indicating suitable procedure through found walls energy involved about -120 kcal mol−1 simulations 14, 19. electron extensively analyze morphology filler microstructure mainly depends micrographs revealed showed smooth appearance 1000×magnification, Figure 1a. CHCN10 means uniform distribution 1b. particles nanodimension be, however, invisible limited resolution scanning microscopy. general, indicated appropriate All compositions containing similar behavior. SEM (A) CHI (B) (magnification 1000 x). Uniform host crucial enhance physical composites. effect, area phase dimension alter states directly reflects gain. Surface, evaluated function presented microscopic larger amounts resulted significantly thinner samples, CHCN50, Table may promote better compaction effect. Film Average (mm) 0.058±0.004a 0.054±0.005a,b 0.050±0.005b 0.052±0.004b specific placed surface. does spread, non-covalent film's decreased values, indicates modification Nanocomposite more comparison although linear increase affinity explained presence functional treatment, roughness should 20. Despite polar hydrophilicity aggregation, implies lower gain multi walled nanotubes/chitosan Therefore, among concentrations analyzed, (w/w) minor value, 80.6±4.2°, achievement angles smaller than 90° characterize spectra confirmed conservation incorporation low intensity bands 1719 3300 cm−1, related carboxyl hydroxyl groups, evidence band 1575 aromatic C=C stretching 21, 3a. absorption amides I II 1655 1560 respectively; −C−H banding 1409 cm−1; C−O C−O−C vibrations 1153, 1094 1026 corresponding saccharide chitosan; O−H 3350 3b. (a) f-SWCN, (b) CHI, (c) (d) (e) CHCN50. exhibited vibration film, 3c, d, e. behavior (maximum 0.5 w/w) bands, leads overlapping bands. absence shifts previous study no fourier-transform Page lines described, agrees Thermal decomposition assessed curves acquired °C, purity qualitatively residual material 700 (less efficient removal metal catalysts purification step production. Typical TG/DTG min−1) min−1. first stage mass (25 °C) water, second (200 400 refers polysaccharide third (500 carbonization polymer. four stages: first, 110 hydration (110 210 non-bonded linked (210 fourth (above °C), similarly Tonset temperatures 50 75 (T10%, T25%, T50% T75%) curves, denotes starts degradation, reproducible determine materials. recommended ASTM standards. samples intercept event. Sample T (°C) T10% T25% T75% 111.4 301.8 358.5 537.7 276.4 f-SWCN 596.6 636.5 662.1 680.6 590.0 72.6 154.7 290.5 465.8 250.8 71.1 149.0 287.2 450.8 253.4 68.2 150.1 292.0 451.0 256.7 Values T10%, show film. Although high stability, provide stability. (Tonset 590 led initial degradation reduction (250.8 respectively), agreement 22. An implied diminish growth crystalline phases chitosan/single-walled involve chitosan, crystal process 23. rise what despite probable crystallinity inclusion, tends act insulator, barring release volatile products degradation. Stress-strain (DMA) Comparing loading arising nanotubes. composites, affected orientation parameters transfer filler. Previous limiting factor phenomenon facilitate arise nanocracks Significant differences noted increases 17.6 11.3 Elongation slightly overall compared typical pattern material, non-linear relationship verified difference, 51.4 value. Notably, sample greater breaking (14.3 reason rigidity hardness derivatives 6. Tensile (MPa) 32. 52±0.67b 35.03±2.42a,b 38.25±0.36a 36.21±1.07a (%) 13.44±1.90a 6.53±0.54b 11.52±2.13a,b 10.04±3.43a,b Young's modulus 0.21±0.07b 0.54±0.04a 0.34±0.07b 0.30±0.03b Due extraordinary properties, stiffness As before, there correlation evidences limit saturation preparation used. homogeneity forming appearance, aggregates. During removal, formation aggregates 24. Based results, possible heterogeneity. Alternatively, faster drying effects. successfully stress-strain expected noticed. during explain unexpected characteristics. financed part Coordenação de Aperfeiçoamento Pessoal Nível Superior - Brasil (CAPES) Finance Code 001. M.A.V.R. M.M.H. thank Prof. Benedito dos Santos Lima Neto supplied SWCN, 7 Dr. Rodrigo C. Sabadini TG FAPESP (grant 2010/19417-0) responsibility Agnieszka Pawlicka. Christoph Morscher help German translation. Open funding enabled organized Projekt DEAL.