This
study investigated the photo-oxidative degradation and biodegradation
behavior of poly(ether-block-amide) (PEBA) multiblock
copolymers with varying amide segments and polyethylene glycol (PEG)
contents. The copolymer films were exposed to ultraviolet (UV) light
in an artificial weathering machine to simulate the photo-oxidative
degradation of these polymers in the environment. The biodegradation
behavior of both the original and UV-exposed PEBA multiblock copolymer
films was studied by immersing them in extracted seawater for 28 d.
The degree of biodegradation was evaluated on the basis of the amount
of carbon dioxide generated. The changes in the morphology, chemical
structure, mechanical properties, molar mass, and microstructure of
the PEBA multiblock copolymer films after UV exposure and biodegradation
tests were investigated using laser microscopy, Fourier transform
infrared spectroscopy, tensile testing, nanoindentation, size-exclusion
chromatography, and wide-angle X-ray scattering. The PEBA multiblock
copolymer with a higher PEG content exhibited faster photo-oxidative
degradation under UV exposure, whereas the nylon-6-segmented PEBA
multiblock copolymer demonstrated excellent biodegradability. Furthermore,
the biodegradability of the PEBA multiblock copolymers significantly
improved after UV exposure. The biodegradability of the PEBA multiblock
copolymers was confirmed through field tests conducted in Ainan, Ehime,
Japan. It was observed that a nylon-6-segmented PEBA multiblock copolymer
containing 56 wt % PEG underwent complete degradation in the marine
environment after six months. The findings of this study provide valuable
insights into the design and optimization of biodegradable polymers
to alleviate microplastic pollution in the environment.