Journal: Advanced Materials (Deerfield Beach, Fla.)

Article Title: Additive Manufacturing of Molecular Architecture Encoded Stretchable Polyethylene Glycol Hydrogels and Elastomers

doi: 10.1002/adma.202512806

Figure Lengend Snippet: Design and chemistry of 3D printable stretchable bottlebrush PEG resins. a–c) A conventional PEG resin consists of relatively long linear PEG (6000 g mol −1 ) and water, which can be UV‐cured to form a randomly crosslinked network. These hydrogels are brittle because of the wide distribution and limited size of network strands. After solvent removal, the linear PEG crystallizes, resulting in stiff and brittle networks. d) The bottlebrush PEG resin is composed of three precursors: i) monofunctional PEG methyl ether acrylate (480 g mol −1 ) as side chains, ii) small N ‐isopropylacrylamide (NIPAM) as spacer monomers, and iii) a difunctional PEG diacrylate (575 g mol −1 ) as crosslinking chains. These monomers can be dissolved in water at very high concentrations, forming colorless, optically transparent, low‐viscosity solutions that can be UV‐crosslinked in ambient air. e,f) The cured resins form a randomly crosslinked bottlebrush polymer network defined by three parameters, [ n sc , r sp , c ]. Here, n sc is the average number of side chains per network strand, which equals the molar ratio between the side chain and the crosslinking chain, r sp is the spacer‐to‐side chain molar ratio, and c is the polymer concentration of the resin. Within the bottlebrush network strand, the NIPAM‐based backbone tends to fold, storing length that can be released upon large deformation, enabling high stretchability. g) Photos of a foldable bottlebrush PEG elastomer ([400, 5, 100]) stretched to ≈1400% strain.

Article Snippet: Instron (Model No. 5966) with a 10 N load cell was used to measure the mechanical properties of the hydrogels and elastomers.

Techniques: Solvent, Viscosity, Polymer, Concentration Assay

Journal: Advanced Materials (Deerfield Beach, Fla.)

Article Title: Additive Manufacturing of Molecular Architecture Encoded Stretchable Polyethylene Glycol Hydrogels and Elastomers

doi: 10.1002/adma.202512806

Figure Lengend Snippet: Bottlebrush PEG elastomers. a–c) Conventional bottlebrush PEG elastomers without spacers: (a) stress‐strain curves, (b) comparison between hydrogels (dotted lines, c = 71wt%) and solvent‐free networks (squares, c = 100%) in the correlation, E ∝( ϵ b ) −α , and (c) five hundred consecutive cycles of loading and unloading (500% strain) for an elastomer [2000, 0, 100]. Horizontal shifts are applied to the curves for the 10th, 50th, 100th, 200th, and 500th cycles for clarity. d–g) Foldable bottlebrush PEG elastomers with NIPAM spacers: (d) stress–strain curves, (e) dependencies of tensile breaking strain and (f) Young's modulus E on the spacer ratio for hydrogels (circles, c = 50 wt%) and elastomers (squares), and (g) consecutive cyclic tensile tests of a foldable bottlebrush PEG elastomer ([400, 5, 100]) with strain up to 1000%. All measurements are performed in ambient air. h) DSC measurements reveal the crystallization temperature T c of long linear PEG (6kDa, black line) networks and cBB PEG (red line) networks. i) Small‐angle X‐ray scattering of solvent‐free bottlebrush PEG networks. j) Ashby‐type plot of printable PEG networks and non‐printable slide‐ring PEG hydrogels (Table , Supporting Information).

Article Snippet: Instron (Model No. 5966) with a 10 N load cell was used to measure the mechanical properties of the hydrogels and elastomers.

Techniques: Comparison, Solvent, Crystallization Assay

Journal: Advanced Materials (Deerfield Beach, Fla.)

Article Title: Additive Manufacturing of Molecular Architecture Encoded Stretchable Polyethylene Glycol Hydrogels and Elastomers

doi: 10.1002/adma.202512806

Figure Lengend Snippet: Applications of photocurable bottlebrush PEG networks. a–c) A cBB PEG network ([2000, 0, 100]) is used as a matrix for creating highly stretchable, highly conductive ionic elastomers. a) Stress–strain curves of a cBB PEG ionic elastomer containing 30 vol% LiTFSI salts; b) Nyquist plot of the impedance spectra for the ionic elastomer at RT. Insets: (upper) schematic illustration of the measurement setup and sample dimensions; (lower) a circuit model used for fitting the data. c) Ashby‐type plot of solvent‐free ionic elastomers based on ionic conductivity and tensile breaking strain. Green circle: bottlebrush PEG ionic elastomer; other symbols: literature data (Table , Supporting Information). Error bar: standard deviation, n = 3. d) Photos of 3D printed structures using resin [400, 5, 50]: i) a kidney, ii) a hollow heart filled with red‐colored water to visualize the hollow structure, iii) a 3D lattice structure swollen in copper (II) nitrate solution, and iv) a solvent‐free gyroid. Scale bars: 10 mm. e) Fluorescence confocal images of NIH 3T3 fibroblasts cultured in aqueous extracts from printed PEG hydrogels with spacer ([400, 5, 50]) and without spacer ([400, 0, 50]) from 1 to 5 days. Scale bars: 200 µm. Cytocompatibility test reveals consistently high cell viability (≈95%) across all samples. f) Multi‐material DLP printing of two different resins, cBB PEG ([400, 0, 100], E ≈ 17 kPa, green) and fBB PEG ([400, 5, 100], E ≈ 200 kPa, yellow), into a linear structure with alternating stiffnesses that can be twisted, bent, and stretched without interface failure. g) A printed pneumatic gripper operating under 20 kPa compressed air to pick up a mushroom. Scale bars: 20 mm.

Article Snippet: Instron (Model No. 5966) with a 10 N load cell was used to measure the mechanical properties of the hydrogels and elastomers.

Techniques: Solvent, Standard Deviation, Fluorescence, Cell Culture