Noncovalent Functionalization of Multiwalled Carbon Nanotube by a Polythiophene-Based Compatibilizer: Reinforcement and Conductivity Improvement in Poly(vinylidene fluoride) Films

Abstract

A new compatibilizer (P2) containing thiophene moiety and poly(dimethylamino ethyl methacrylate) (PDMAEMA) group is prepared by atom transfer radical polymerization (ATRP). The dispersion of multiwalled carbon nanotube (MWNT) with P2 in N,N-dimethylformamide (DMF) is stable for >3 months. The UV–vis spectrum of the MWNT/P2 dispersion shows a blue shift, and the photoluminescence (PL) spectrum also indicates a quenching suggesting a significant interaction between MWNT and P2. SEM and TEM micrographs suggest a good dispersion and coating of P2 on MWNT surface. The Raman D/G band intensity ratio remains unchanged, and a small shift of >CO vibration peak to lower energy suggests an interaction between P2 and MWNT. The presence of CH−π and π–π interactions between P2 and MWNT is evidenced from UV–vis, PL, Raman, FTIR, and NMR spectral results facilitating the wrapping of P2 on MWNT surface. Poly(vinylidene fluoride) (PVDF)/P2/MWNT composites (PCMx, x indicates wt % of MWNT) are prepared by solvent casting method with 0.02% (w/v) P2 and varying concentration of MWNT in DMF. The SEM and TEM micrographs show a homogeneous dispersion of MWNT/P2, and the optical micrographs indicate a loss of spherulitic morphology in the composites. FTIR spectra suggest the formation of piezoelectric β-phase PVDF and the presence of specific interaction between >CO group of P2 and >CF2 group of PVDF. The storage modulus (G′) shows a highest increase (122%) in PCM0.5 among the PVDF/MWNT composites. The increase in Young’s modulus, tensile strength, and toughness in PCM 0.05 is two to three times higher than that without P2. Analysis of Young’s modulus data suggests a random distribution of MWNT in the composite. The PCM1 has the highest conductivity (2 × 10–2 S/cm), and the system shows a very low percolation threshold at 0.06 wt % MWNT. The conductivity data obeys the 3-D percolation model. By comparing the above mechanical property and conductivity data with that of other MWNT/PVDF composites, it is argued that the noncovalently functionalized MWNT with P2 is a better reinforcing agent.

Electrically conductive nanocomposite adhesives based on epoxy or chloroprene containing polyaniline, and carbon nanotubes

“…Carboxylation is the widely used approach in order to produce stable water dispersion of carbon nanotubes and for further CNTs functionalization via carboxylic groups. In addition, CNTs can be further stabilized by chemically attached organic reagents or polymer chains [18][19][20][21].…”

Sensitivity of Pressure Sensors Enhanced by Doping Silver Nanowires

“…Attempts have also been made to induce crystalline polar β phase formation in PVDF by doping chemical agents. Boey [15] and Mandal [16] prepared PVDF composites by adding carbon nanotubes into PVDF, which showed that the composite has a higher crystalline β phase content. However, carbon nanotubes are hard to disperse and cost a lot.…”

Grafting of pH-sensitive poly (N,N-dimethylaminoethyl methacrylate-co-2-hydroxyethyl methacrylate) onto HNTS via surface-initiated atom transfer radical polymerization for controllable drug release

“…After copolymerization, weight loss in the range of 100-700 °C increases to 28.6% and 27.4% in HNTs-g-PHD50 and HNTs-g-PHD70 respectively. The copolymer chains exhibit two stages of weight loss; the first one at 260 °C related to thermal decomposition of oxygen containing side chain groups and the second one at 420 °C originated from decomposition of polymer backbones [52]. Also, the second stage of degradation of HNTs at 497.6 °C decreases to 477.0 °C by polymer attachment (Figure 3 The surface morphology of HNTs before and after polymer grafting was studied by SEM as shown in Figure 5.…”