"Measuring the Glass Transition Temperature at the Nanoscale using Atomic Force Microscopy"
Polymers and other amorphous solid systems can be classified and defined by several features: a notable one being their glass transition temperature. This transition is characterized by various chemical and physical changes that occur during a shift from a brittle, glass-like phase to a soft, rubbery phase.(1) Conventional techniques for the measurement of this glass transition are limited to bulk samples, making averaged conclusions about recorded results. However, there are many real-world cases of heterogeneous domains down to the micro- and nanometer regimes which contain valuable chemical and mechanical information and influence the overall system they reside in. As a new type of pollutant, microplastics (MPs) have been recently found in different aquatic environments, such as rivers, lakes, and oceans. It is generally believed that MPs can cause greater environmental risks than large plastics, and so the behaviors of MPs have attracted widespread attention, since understanding the aging process of MPs and their potential effects will help to decrease the uncertainty in risk assessment of MPs.(3) One approach used to monitor the aging of microplastics is the simultaneous recording of infrared spectra in conjunction with local glass transition temperature measurements using atomic force microscopy.(4) In this work, the novel method of nanoscale thermal analysis (nano-TA) will be introduced. Nano-TA is a local thermal analysis technique which combines the high spatial resolution imaging capabilities of atomic force microscopy with the ability to obtain understanding of the thermal behavior of materials with a spatial resolution of sub-100nm,(2) with an overall emphasis of improved structure understanding for the future development of plastic products and recycling.
1) Qian, Z., Cao, Z., Galuska, L., Zhang, S., Xu, J., & Gu, X. (2019, April 25). Glass Transition Phenomenon for Conjugated Polymers. Macromolecular Chemical Physics.
2) Bruker Nano Surfaces. (2021, January 15). Nanoscale Thermal Analysis (nano-TA) to Determine the Thermal Properties of Polyphasic Polymers. AZoM.
3) Luo, H., Xiang, Y., Zhao, Y., Li, Y., & Pan, X. (2020, July 14). Nanoscale Infrared, Thermal and Mechanical Properties of Aged Microplastics Revealed by an Atomic Force Microscopy Coupled with Infrared Spectroscopy (AFM-IR) Technique. Science of the Total Environment.
4) Guen, E., Klapetek, P., Puttock, R., Hay, B., Allard, A., Maxwell, T., . . . Gomès, S. (2020, May 30). SThM-based Local Thermomechanical Analysis: Measurement Intercomparison and Uncertainty Analysis. International Journal of Thermal Sciences.