Artificial muscles based on stimuli-responsive polymers usually exhibit mechanical compliance, versatility, and high power-to-weight ratio, showing great promise to potentially replace conventional rigid motors for next-generation soft robots, wearable electronics, and biomedical devices. In particular, thermomechanical liquid crystal elastomers (LCEs) constitute artificial muscle-like actuators that can be remotely triggered for large stroke, fast response, and highly repeatable actuations. Here, we introduce a digital light processing (DLP)–based additive manufacturing approach that automatically shear aligns mesogenic oligomers, layer-by-layer, to achieve high orientational order in the photocrosslinked structures; this ordering yields high specific work capacity (63 J kg−1) and energy density (0.18 MJ m−3). We demonstrate actuators composed of these DLP printed LCEs’ applications in soft robotics, such as reversible grasping, untethered crawling, and weightlifting. Furthermore, we present an LCE self-sensing system that exploits thermally induced optical transition as an intrinsic option toward feedback control.

Polymer networks cross-linked by reversible metal-ligand interactions possess versatile mechanical properties achieved simply by varying the metal species and quantity. Although prior experiments have revealed the dependence of the network’s...

emerging as an enabling technology. [1][2][3][4] The combination of flexibility and responsiveness allows applications in various fields, including wearable electronics, soft robotics, drug delivery, biomedical devices, and biomimetic design. [5][6][7][8][9][10] Among various material options, polymers play an essential role in fabricating flexible sensors and soft actuators due to their tailorability and the potential of integrating multiple functionalities, such as adaptive response to signals (e.g., chemical, mechanical, electrical), energy harvesting and storage, and biochemical sensing. [3,10] Adding responsive functionality to a polymer often involves methods such as copolymerizing monomers with different capability, attaching layers of active materials to a polymer matrix, building in molecular orientation or internal polarization, introducing structural heterogeneity by combining amorphous and crystalline domain or multi-layer assembly, and preparing composites by hybridizing organic and inorganic materials. [2,[11][12][13][14] Among various techniques, utilizing dynamic chemistry to enable polymer responsivity has received significant attention in the past few decades. [15,16] Reversible interactions, including dynamic covalent bonding, hydrogen bonding, ionic bonding, π-π stacking, and metal-ligand coordination, are susceptible to environmental variation and can achieve multiple physical and chemical responses via bond breaking and reforming. [17][18][19][20][21] Fascinating material properties arise from disrupting the equilibrium state of dynamic bonding, for example: polymers with spiropyran go through force-induced covalent-bond activation and give rise to visible color and fluorescence; supramolecular polymers containing metal-ligand motifs can self-heal by exposing to ultraviolet irradiation; and polymers functionalized by self-complementary hydrogen bonded ureidopyrimidinone (UPy) moieties shows shape-memory effect through temperature change. [22][23][24] Among these options, metal-ligand coordination bonding is particularly appealing to realize a particular desired response, because of the ease of tuning the stability of the bond.One of the most popular polymers for fabricating sensors and actuators is polydimethylsiloxane (PDMS). [2,7] It commonly serves as an essential substrate or a responsive component due to the attractive physical and chemical properties, including low Polymers are at the core of emerging flexible sensor and soft actuator technology. Ideal candidates not only respond to external stimuli but also have programmable response intensity and speed. Incorporating dynamic interactions into polymers has been widely studied. However, most research has focused on synthesis methods and on optical and mechanical effects of these interactions. Here, a new and tunable method of enabling environmentally adaptive polymers are introduced. Specifically, polar functionalities are "hidden" within polydimethylsiloxane (PDMS). When unveiled, these polar functionalities change the hydrophilicity ...