Synthesis and characterization of polyetherimides containing multiple ether linkages and pendent pentadecyl chains

Polyetherimide (PEI) nanocomposite with WS2 nanotubes

Nanocomposite materials, integrating nanoscale additives into a polymer matrix, hold immense promise for their exceptional property amalgamation. This study delves into the fabrication and characterization of polyetherimide (PEI) nanocomposite strings fortified with multiwall WS2 nanotubes. The manufacturing process capitalizes on the preferential alignment of WS2 nanotubes along the string axis, corroborated by scanning electron microscopy (SEM). Mechanical measurements unveil a remarkable acceleration of strain hardening in the nanocomposite strings, chiefly attributed to the WS2 nanotubes. Structural analyses via X-ray diffraction (XRD) and wide-angle X-ray scattering (WAXS) reveal intriguing structural alterations during tensile deformation. Notably a semi-crystalline framework ∼100 nm in diameter surrounding the WS2 nanotubes emerges, which is stabilized by the π-π interactions between the PEI chains. The amorphous majority phase (97% by volume) undergoes also major structural changes upon strain becoming more compact and closing-up of the distance beweeetn the PEI chains. Dynamic mechanical analysis (DMA) demonstrates improved thermal stability of the evolved semi-crystalline π-π oriented PEI molecules, characterized by delayed thermal "structural melting", underscoring the pivotal role of the WS2 nanotubes in reinforcing the nanocomposite. The insight gained in this study of WS2 nanotube-reinforced PEI nanocomposite strings, could offer diverse applications for such tailor-made polymeric materials.

Direct Creation of Highly Conductive Laser-Induced Graphene Nanocomposites from Polymer Blends

The current state-of-the-art mixing strategies of nanoparticles with insulating polymeric components have only partially utilized the unique electrical conductivity of graphene in nanocomposite systems. Herein, this paper reports a nonmixing method of direct creation of polymer/graphene nanocomposites from polymer blends via laser irradiation. Polycarbonate-laser-induced graphene (PC-LIG) nanocomposite is produced from a PC/polyetherimide (PC/PEI) blend after exposure to commercially available laser scribing with a power of ≈6 W and a speed of ≈2 cm s^-1 . Extremely high electrical conductivities are obtained for the PC-LIG nanocomposites, ranging from 26 to 400 S m^-1 , depending on the vol% of the starting PEI phase in the blend. To the authors' knowledge, these conductivity values are at least one order of magnitude higher than the values that are previously reported for conductive polymer/graphene nanocomposites prepared via mixing strategies. The comprehensive microscopy and spectroscopy characterizations reveal a complete graphitization of the PEI phase with columnar microstructure embedded in the PC phase.

Synthesis and characterization of polyhydrazides and poly(1,3,4-oxadiazole)s containing multiple arylene ether linkages and pendent pentadecyl chains

A new diacylhydrazide monomer, namely, 4-(4-(4-(4-(hydrazinocarbonyl)phenoxy)-2-pentadecylphenoxy)phenoxy) benzohydrazide (HPPDPB), was synthesized starting from 4-(4-hydroxyphenoxy)-3-pentadecylphenol. HPPDPB was polycondensed with terephthalic acid chloride (TPC), isophthalic acid chloride (IPC) and a mixture of TPC and IPC (50:50 mol%) to obtain polyhydrazides containing multiple arylene ether linkages in the backbone and pendent pentadecyl chains. Polyhydrazides were subsequently cyclized in the presence of phosphorus oxychloride to obtain the corresponding poly(1,3,4-oxadiazole)s. Polyhydrazides and poly(1,3,4-oxadiazole)s exhibited inherent viscosities in the range 0.65–0.72 dL g−1 and 0.54–0.62 dL g−1, respectively, which indicated the formation of reasonably high-molecular weight polymers. Polyhydrazides were soluble in polar aprotic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide (DMAc), 1-methyl-2-pyrrolidinone and pyridine whereas poly(1,3,4-oxadiazole)s exhibited excellent solubility even in common organic solvents such as chloroform, dichloromethane and tetrahydrofuran. Tough, transparent and flexible films of polyhydrazides and poly(1,3,4-oxadiazole)s could be cast from DMAc and chloroform solutions, respectively. X-Ray diffraction studies revealed amorphous nature of polyhydrazides and poly(1,3,4-oxadiazole)s and the formation of layered structure was observed due to ordered packing of pentadecyl chains. The 10% decomposition temperature ( T10) values for poly(1,3,4-oxadiazole)s were in the range 425–440°C indicating their good thermal stability. Glass transition temperature ( Tg) values of polyhydrazides and poly(1,3,4-oxadiazole)s were in the range 175–192°C and 92–103°C, respectively. The excellent solubility characteristics and the large gap between Tg (92–103°C) and T10 (425–440°C) values give poly(1,3,4-oxadiazole)-containing pendent pentadecyl chains better opportunities for processability.