Core-crystalline nanoribbons of controlled length via diffusion-limited colloid aggregation

Artículo

Autoría

SCHMARSOW, RUTH NOEMÍ ; CEOLIN, MARCELO RAUL ; ZUCCHI, ILEANA ALICIA ; SCHROEDER, WALTER FABIAN

Fecha

2019

Editorial y Lugar de Edición

ROYAL SOC CHEMISTRY

Revista

SOFT MATTER, vol. 15 (pp. 4751-4760) ROYAL SOC CHEMISTRY

Resumen Información suministrada por el agente en SIGEVA

It has been previously reported that poly(ethylene) (PE)-based block copolymers self-assemble in certain thermosetting matrices to form a dispersion of one-dimensional (1D) nanoribbons. Such materials exhibit exceptional properties that originate from the high aspect ratio of the elongated nano-objects.However, the ability to prepare 1D assemblies with well-controlled dimensions is limited and represents a key challenge. Here, we demonstrate that the length of ribbon-like nanostructures can be ... It has been previously reported that poly(ethylene) (PE)-based block copolymers self-assemble in certain thermosetting matrices to form a dispersion of one-dimensional (1D) nanoribbons. Such materials exhibit exceptional properties that originate from the high aspect ratio of the elongated nano-objects.However, the ability to prepare 1D assemblies with well-controlled dimensions is limited and represents a key challenge. Here, we demonstrate that the length of ribbon-like nanostructures can be precisely controlled by regulating the mobility of the matrix during crystallization of the core-forming PE block.The selected system to prove this concept was a poly(ethylene-block-ethylene oxide) (PE-b-PEO) block copolymer in an epoxy monomer based on diglycidyl ether of bisphenol A (DGEBA). The system was activated with a dual thermal- and photo-curing system, which allowed us to initiate the epoxy polymerization at 120 1C until a certain degree of conversion, stop the reaction by cooling to inducecrystallization and micellar elongation, and then continue the polymerization at room temperature by visible-light irradiation. In this way, crystallization of PE blocks took place in a matrix whose mobility was regulated by the degree of conversion reached at 120 ºC. The mechanism of micellar elongation wasconceptualized as a diffusion-limited colloid aggregation process which was induced by crystallization of PE cores. This assertion was supported by the evidence obtained from in situ small-angle X-ray scattering (SAXS), in combination with differential scanning calorimetry (DSC) and transmission electron microscopy (TEM).

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Palabras Clave

BLOCK COPOLYMERNANORIBBONSEPOXY

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http://hdl.handle.net/11336/119181