Nucleation Mechanisms of Aromatic Polyesters, PET, PBT, and PEN, on Single‐Wall Carbon Nanotubes: Early Nucleation Stages

Abstract

Nucleation mechanisms of poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), and poly(ethylene naphthalate) (PEN) on single-wall carbon nanotubes (SWNTs) are proposed, based on experimental evidence, theoretical epitaxy analysis, and semiempirical quantum chemical calculations. In order to elucidate early nucleation stages polyester-coated nanotubes were obtained from highly diluted solutions. High-resolution transmission electron microscopy (HRTEM) revealed helical morphologies for PET/SWNTs and PEN/SWNTs and the formation of lobules with different orientations for PBT/SWNTs. To explain the morphological behavior one model was proposed based on crystallographic interactions, that is, epitaxy. Theoretical epitaxy calculations indicated that epitaxy is not possible from the strict epitaxy point of view. Instead, aromatic self-assembly mechanism was proposed based onπ-πinteractions and the chirality of the nanotube. It was proposed that the mechanism implies two steps to produce helical or lobular morphologies with different orientations. In the first step polymer chains were approached, aligned parallel to the nanotube axis and adsorbed due to electrostatic interactions and the flexibility of the molecule. However, due toπ-πinteractions between the aromatic rings of the polymer and the nanotube, in the second step chains reoriented on the nanotube surface depending on the chirality of the nanotube. The mechanism was supported by semi-empirical calculations.

Effect of MWNTs concentration and cooling rate on the morphological, structural, and electrical properties of non‐isothermally crystallized PEN/MWNT nanocomposites

“…In our case, as the cooling rate decreased the intensity of patterns in nanocomposites became stronger indicating that large β crystals were developed. These important changes associated with crystalline structure and crystallinity may be attributed to the easily adsorption of PEN chains on nanotubes by means of aromatic self‐assembly nucleation, as previously reported …”

“…At the higher cooling rate of 20°C min −1 , the addition of 1 wt % of CNT has a negligible effect on T c , nonetheless, has a marked effect on the enthalpy of crystallization, which means that, even at these conditions, the CNT do still present a marked nucleating effect on PEN. This nucleating effect may be attributed to the favorable π−π interactions between PEN and the CNT surface that make it possible …”

“…Herein, the effect of nanotube concentration and cooling rate on the morphological, structural and electrical properties of non‐isothermally crystallized PEN‐multiwall carbon nanotubes nanocomposites is studied. It has been reported that carbon nanotubes are good nucleating agents for PEN throughout self‐assembly nucleation which make it easier to control the morphology and electrical properties of nanocomposites for their possible application in charge dissipative materials for sensitive items.…”

Periodic Functionalization of Graphene‐Layered Alumina Nanofibers with Aromatic Thermosetting Copolyester via Epitaxial Step‐Growth Polymerization

“…Besides, the aromatic structure of the graphitic layers could form a base for π–π predominant interactions with corresponding aromatic rings in the ATSP backbone. Overall, due to the structural order of the ANFC surface, ATSP chains reorganized their chain configurations, enabled through polymer intrinsic flexibility at elevated temperatures, and subsequently formed lamellar structures . Also, we highlight that the ANFC strands did not substantially change the genuine cure characteristics of the ATSP resin.…”

Nucleation and crystallization of random aliphatic-butylene terephtalate copolyester

“…Espinoza-Martinez et al [31] proposed that aromatic structure of carbon nanotubes can act as a template by means of p-p interactions for the nucleation of semicrystalline polymers containing aromatic rings in their backbones such as poly(butylene terephthalate) (PBT). In both cases of PBASGT and PG7L or PBASGT and PB153L the aromatic rings are present, so the structure can be important.…”