The use of photopolymers for 3D printing facilitates high-precision fabrication of geometrically complex structures, offering exceptional dimensional accuracy and rapid curing capabilities that position it as a cornerstone of modern additive manufacturing. However, conventional photopolymers form permanently crosslinked networks, which are resistant to recycling. This inherent limitation generates persistent waste streams that are fundamentally incompatible with circular economy principles. Consequently, the development of recyclable photopolymers that maintain printability while enabling closed-loop material recovery represents a critical Frontier for sustainable manufacturing. Advancing these materials will remain essential for reconciling technological progress with environmental stewardship in the foreseeable future. This review examines recent breakthroughs in recyclable photopolymer systems for 3D printing. First, mainstream photopolymerization techniques compatible with recyclable materials are outlined, followed by an elucidation of core design strategies incorporating chemical depolymerization, thermo-mechanical reprocessing, and noncovalent interactions. Fundamental recycling mechanisms are detailed alongside performance modulation methodologies. Furthermore, emerging applications in soft robotics, wearable devices, and bioelectronic devices where recyclable photopolymers enable multifunctional devices are highlighted. Finally, persistent challenges regarding network durability and recycling efficiency are addressed, and future research directions toward truly sustainable 3D printing are proposed.

Unconventional phases are often assembled from molecules with unique chemical structures. Herein, we report the facile synthesis and phase behavior of a series of giant bolaform lipids featuring an oligosiloxane-functionalized polyhedral oligomeric silsesquioxane (SixPOSS) tethered at the middle of a polystyrene (PS) chain and two perfluoroalkyl-functionalized POSS (FPOSS) moieties attached, one at each terminus. By tuning the volume fraction of the SixPOSS, various phases have been identified utilizing small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM), including lamellae (LAM), three-phase-four-layer lamellae (LAM3), and a unique column in undulating lamellae phase with c2mm symmetry (Colc2-in-LAMu). Temperature-dependent experiments and a semiquantitative calculation of the structural parameters were carried out to analyze the structural feature and formation mechanism of this unconventional phase. Notably, the thin film morphologies of these giant bolaform lipids exhibit similar features with the lamellar layers oriented parallel to the silicon wafer surface. This study provides valuable insights into fine-tuning macromolecular assembly and understanding the rationale of unconventional phase formation via molecular topology engineering.

Three-dimensional covalent organic frameworks (3D COFs) have emerged as a promising yet underexplored class of porous materials for the selective adsorption of sulfur hexafluoride (SF6). Herein, we report a microporous 3D COF (3D-TMTAPB-NDA-COF) constructed from a 6-connected polyhedral node and a naphthalene-based linear linker. Structural analysis confirms that 3D-TMTAPB-NDA-COF adopts an acs topology with Class IIIa interpenetration. Notably, the COF exhibits a high SF6 uptake of 39.5 cm3 g–1 at 298 K and an exceptional SF6/N2 (10/90) selectivity of 359 at 1 bar, representing the highest value reported among purely organic porous materials. This work not only introduces a high-performance candidate for selective SF6 capture but also provides valuable insights into the rational design of functional 3D COFs for advanced gas adsorption and separation applications.