Investigating polymer crystallization at the nanoscale using AFM-IR

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Controlling the morphology and crystallization of polymers and composites is crucial because it is directly related to the final properties of the material. Semi-crystalline polymers are an important fraction of commercial polymers. It is well known that miscible polymeric blends can have a variety of morphologies and crystallization mechanisms that depend on the difference in the melting temperature of each component, the blend composition and the crystallization conditions. These phenomena become more complex in the binary blends of miscible and crystallizable polymers where the two components are in competition to reach the final structure (e.g. shape, orientation, morphology, topography, texture and density). However, the examination of the distribution of polymers in crystallizable polymer blends, especially at the submicron scale, is technically difficult despite the progress of the physicochemical characterization methods. Recently, we have been able to use an advanced equipment, i.e. atomic force microscopy-infrared spectroscopy (AFM-IR), to study the crystallization and nano-diffusion of polymers in miscible and immiscible blends, while recording their high-resolution topographic images at the nanoscale level. This advancement was made possible through the ability to qualitatively identify the chemical composition of the compound through AFM-IR. The preliminary results have led to several publications and awards. In this research program, we will develop new approaches to better understand the miscibility, crystallization and distribution of biodegradable polymers, particularly the binary polymeric blends at the nanoscale level using mainly atomic force microscopy coupled with an infrared spectroscopy (AFM-IR) or a thermocouple (Nano-TA). The simulation of the dynamics of the polymer blends will be carried out in order to understand the molecular structure during the crystallization using mainly the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) Molecular Dynamics Simulator software dedicated to polymers and biomolecules. Nanoscale characterization methods help to better answer the open questions in the literature, particularly the molecular arrangements, lamella development mechanisms, morphology and phase transition in a spherical structure that are more important features to detect the final behavior of biopolymer materials. Understanding the diffusion of polymers in relation to the structure of spherulites and the operating conditions in polymer blends will provide an important scientific contribution and open a new pathway for crystallization studies in complex systems, such as ternary and quaternary blends. Improving the properties of the polymer blends will extend the field of use of these biopolymers in various applications such as in biomedical materials and biological tissues (globally, market of US$25.4 billion for 2019).