Naturally
derived cellulose nanomaterials (CNMs) with
desirable
physicochemical properties have drawn tremendous attention for their
versatile applications in a broad range of fields. More recently,
Janus amphiphilic cellulose nanomaterial particles with asymmetric
structures (i.e., reducing and nonreducing ends and crystalline and
amorphous domains) have been in the spotlight, offering a rich and
sophisticated toolbox for Janus nanomaterials. With careful surface
and interfacial engineering, Janus CNM particles have demonstrated
great potential as surface modifiers, emulsifiers, stabilizers, compatibilizers,
and dispersants in emulsions, nanocomposites, and suspensions. Naturally
derived Janus CNM particles offer a fascinating opportunity for scaling
up the production of self-standing Janus CNM membranes. Nevertheless,
most Janus CNM membranes to date are constructed by asymmetric fabrication
or asymmetric modification without considering the Janus traits of
CNM particles. More future research should focus on the self-assembly
of Janus CNM particles into bulk self-standing Janus CNM membranes
to enable more straightforward and sustainable approaches for Janus
membranes. This review explores the fabrication, structure–property
relationship, and Janus configuration mechanisms of Janus CNM particles
and membranes. Janus CNM membranes are highlighted for their versatile
applications in liquid, thermal, and light management. This review
also highlights the significant advances and future perspectives in
the construction and application of sustainable Janus CNM particles
and membranes.