data set fully for the entire sample of 11 PNs.]{}

Introduction
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The planetary nebula (PN) phase marks the last throes of stellar evolution for low to intermediate initial mass stars (of about 0.8–8M$_{\odot}$, @kwokbook). During this phase, the circumstellar envelope of gas and dust, which is created by mass loss in the preceding asymptotic giant branch (AGB) and post-AGB phases, undergoes a dramatic transformation (i.e., ionization, photo-dissociation, and dynamical shaping) caused by the fast wind and the intense radiation from the central star and by the less powerful but often significant interstellar radiation field coming from the surrounding interstellar space. As a consequence, a wide variety of underlying physical conditions are showcased within PNs, from fully ionized hot plasma to dusty cold atomic/molecular clouds, which exist (at least to first order) in a stratified manner around the central star. Therefore, PNs provide excellent astrophysical laboratories to test theories of stellar evolution as well as theories of gas-dust dynamical processes in interacting stellar winds that can also interact with the surrounding interstellar medium (ISM).

While PN investigations have been traditionally done through diagnostics of optical emission lines, PNs are bright sources at a wide range of wavelengths from the radio 