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1 advances.scienceag.org/cgi/content/full/3/4/e160890/dc1 Suppleentary Materials for Direct 4D printing via active coposite aterials Zhen Ding, Chao Yuan, Xirui Peng, Tiejun Wang, H. Jerry Qi, Martin L. Dunn This PDF file includes: Published 1 April 017, Sci. Adv. 3, e (017) DOI: /sciadv section S1. Theroechanical properties of polyers section S. Additional results section S3. Geoetry of printed saples section S4. Modeling and siulation fig. S1. Theroechanical properties of elastoer (TangoBlack+) and glassy polyer SMP (VeroClear) as deterined by DMA. fig. S. Contribution in overall curvature fro CTE isatch strain and built-in copressive strain. fig. S3. A lattice structure (diensions in ) printed in an open configuration and then deployed into a copact configuration upon heating. fig. S4. Design of the printed saple in Fig. 3A. fig. S5. Design of the printed saple in Fig. 3B. fig. S6. Design of the printed saple in Fig. 3C. fig. S7. Design of the printed saple in Fig. 4A. fig. S8. Design of the printed saple in Fig. 4B. fig. S9. Design of the printed saple in Fig. 4C. fig. S10. Design of the printed saple in fig. S3. table S1. List of paraeters for constitutive odel.

2 section S1. Theroechanical properties of polyers We easured the storage odulus, tan delta, and theral strain versus teperature of both the SMP and the elastoer. These results were obtained with a layer printing tie of 68s, but differ insignificantly fro results with different printing ties. Upon heating the storage odulus of Veroclear decreases slightly until ~40 o C above which it reduces draatically. In contrast, the decrease of Tangoblack+ storage odulus has basically ceased after 10 o C (fig. S1A). The peak of tan delta in fig. S1B indicates the glass transition teperature (Tg) ~6 C and ~8 o C for Veroclear and Tangoblack+, respectively. Tangoblack+ has an alost linear theral strain ~1% fro roo teperature (5 o C) to 80 o C, while it is ~0.8% for Veroclear and nonlinear indicating a phase transition in that teperature range. The isatch theral strain between Veroclear and Tangoblack+ is less than 0.% in the easured teperature range. The residual theral strains of both Veroclear and Tangblack+ are alost zero after they were cooled back to roo teperature in a heating-cooling cycle. fig. S1. Theroechanical properties of elastoer (TangoBlack+) and glassy polyer SMP (VeroClear) as deterined by DMA. (A) Storage odulus versus teperature; (B) Tan delta versus teperature; (C) Theral strain in one heating (solid lines) and cooling (dash lines) cycle. section S. Additional results We quantify the ratio between the built-in copressive strain and CTE isatch strain towards bending curvature. The CTE isatch also contributes to the overall bending, but to a lesser extent, especially with the longer layer printing tie.

3 fig. S. Contribution in overall curvature fro CTE isatch strain and built-in copressive strain. Various shape actuations can be achieved via our direct 4d printing approach by caully configuring aterials in structure. Opposite to Fig. 4A, where the printed collapsed lattice structure deploys into an open configuration upon heating, a printed open lattice structure here draatically collapses into a copact one with a structural copression of ~6% and a lateral contraction of ~6% upon heating. Finite eleent siulations (the pic at the right botto of fig. S) show good agreeent with a predicted copression of 64% and lateral contraction of 7%. fig. S3. A lattice structure (diensions in ) printed in an open configuration and then deployed into a copact configuration upon heating. The structure has a size of and a SMP/elastoer bilayer thicknesses of 0.4/0.4.

4 section S3. Geoetry of printed saples The designs of the printed saples are presented below. In the figures, all diensions are in. For Fig. 1C, two-layer flat strips of with equal Tangoblack+ and Veroclear thickness layers fabricated with a layer printing tie of 68 s and a total printing tie of 66 in. For Fig. 1D, two-layer flat strips of with equal Tangoblack+ and Veroclear thickness layers fabricated with a layer printing tie of 58 s and a total printing tie of 56 in. For Fig. A, pure Tangoblack+ or Veroclear flat strips of fabricated with a series of layer printing ties (10, 13, 5, 37, 49, 58, 68 and 74 s) and total printing ties (11, 16, 31, 46, 60, 75, 90 and 104 in). For Fig. B, two-layer flat strips of with equal Tangoblack+ and Veroclear thickness layers fabricated with a series of layer printing ties (10, 13, 5, 37, 49, 58, 68 and 74 s) and total printing ties (10, 13, 3, 34, 45, 56, 66, and 77 in). For Fig. C, two-layer flat strips of 60 5 t with equal Tangoblack+ and Veroclear thickness layers, where t (0.6, 1.,.4, 4.8 ) is the total thickness fabricated with a series of layer printing ties (10, 13, 5, 37, 49, 58, 68 and 74 s). The total printing ties for strip of under layer printing ties of 10, 13, 5, 37, 49, 58, 68 and 74 s, for exaple, are 10, 13, 3, 34, 45, 56, 66, and 77 in, respectively. The total printing ties of other strips are basically proportional to their thicknesses. For Fig. D, two-layer flat strips of , where the Tangoblack+ volue (thickness) fraction varies with a series of values (.5, 0, 40, 50, 60, 80, 90, 95%) fabricated with a layer printing tie of 68 s and a total printing tie of 89 in. fig. S4. Design of the printed saple in Fig. 3A. Two-layer flat strips of , where Tangoblack+ ( ) and Veroclear ( ) segents alternate along the length fabricated with a layer printing tie of 68 s and a total printing tie of 70 in.

5 fig. S5. Design of the printed saple in Fig. 3B. Two-layer flat strips of with Veroclear/Tangoblack+ thicknesses of 0./0.5 and an SMP separator is oriented at 45 o fabricated with a layer printing tie of 68 s and a total printing tie of 70 in. fig. S6. Design of the printed saple in Fig. 3C. Two-layer flat rings of 10/68.6- outer/inner diaeter and 1.- thickness, where Veroclear/Tangoblack+ has thicknesses of 0.4/0.8 and alternates along the circuference, fabricated with a layer printing tie of 68 s and a total printing tie of 89 in.

6 fig. S7. Design of the printed saple in Fig. 4A. Closed lattice with an overall size of Veroclear/Tangoblack+ (0.35/0.35 ) bilayers are printed perpendicular to the build tray and fabricated with a layer printing tie of 68 s and a total printing tie of 310 in.

7 fig. S8. Design of the printed saple in Fig. 4B. Closed lattice with an overall size of Veroclear/Tangoblack bilayers are printed perpendicular to the build tray, have a series of thicknesses of 0.8/0.8, 0.6/0.6, 0.3/0.9, and 0./0.6, and are fabricated with a layer printing tie of 68 s and a total printing tie of 73 in. fig. S9. Design of the printed saple in Fig. 4C. Flat star-shaped bilayer structure consists of 6 identical equilateral triangles, each of which has outer/inner side length of 60/ The

8 Veroclear/Tangoblack+ thicknesses are 0.88/1.77 and the structure is fabricated with a layer printing tie of 68 s and a total printing tie of 144 in. For Fig. 4D, printed flower consisting of five layers of petals with a gap of 0.5 between each. The petals in different layers are siilar in shape and size, except for the outer radius (4, 48, and 51 ). Each petal is a flat bilayer structure, and has a SMP/elastoer thicknesses of 0.3/0.3. The axiu petal width is less than 4.5. The elastoer is Tango+, while SMP is the digital aterials/coposites fro Pureverowhite, Veroyellow, Veroagenta, Veroblack and Verocyan. The printing tie for petals fro the botto layer to top layer is 5, 37, 49, 58 and 74 s, respectively, and the total printing tie for the flower is 35 in. Unlike the other saples, the flower is printed on the Stratasys J750 ultiaterial printer which supports the ultiple color aterials. In fig. S1, flat strips of ~0 7 1 (Veroclear and Tangoblack+) for storage odulus/glass transition easureents and ~ for theral strain easureents. These saples are fabricated with a layer printing tie of 68 s and the total printing tie of 8 in for the forer and 66 in for the latter.

9 fig. S10. Design of the printed saple in fig. S3. Open lattice with an overall size of Veroclear/Tangoblack bilayers are printed perpendicular to the build tray, have a thicknesses of 0.4/0.4, and are fabricated with a layer printing tie of 68 s and a total printing tie of 310 in. section S4. Modeling and siulation In order to describe the shape change behavior of the printed structures and reveal its echanis, we build a odel that accounts for the teperature-dependent theroechanical behavior of SMP aterial and the experientally-deterined built-in copressive strain in the elastoer. Multibranch odel is used to describe the theroechanical property of SMP aterial, in which one equilibriu branch and several theroviscoelastic nonequilibriu branches are arranged in parallel (4). Maxwell eleents are used in the nonequilibriu branches to represent the stress relaxation behavior of the aterial, and the total stress of the SMP aterial can be expressed as

10 Where n t t eq e S dt S ES es Enon exp ds 0 s 1 s T eq E S is the elastic odulus of the equilibriu branch, (S1) E non and are the elastic odulus and teperature dependent relaxation tie of the th nonequilibriu branch, es is the echanical strain calculated by subtracting the theral strain ST fro total strain. Based on the tie teperature superposition principle (TTSP), can be deterined by using the R relaxation tie at erence teperature shift where a T a shift T (S) R T is the teperature dependent shifting factor. The shifting factors can be calculated by cobining the Willias Landel Ferry (WLF) equation and Arrhenius-type equation (4). When the teperature is higher than the erence teperature T, the shifting factor can be expressed by using WLF equation C1 T T shift log a T, T T C T T (S3) where C 1, C and T are the aterial paraeters to be characterized. If the teperature is lower than the erence teperature T, the shifting factor can be expressed by Arrhenius-type equation: (S1) shift AF 1 1 c ln a T, T T k T T (S4) where A, Fc and k are the aterial constant, configurational energy and Boltzann s constant respectively. The DMA test results in the Suppleentary Inforation were used to identify the above paraeters eq non R including E S, E,, C 1, C and AFc/k. The storage odulus at 80 can be considered as the eq equilibriu odulus E S as the relaxation tie at this teperature in each nonequilibriu branch is inial. For the ulti-branch linear odel, the teperature dependent storage odulus E l E T and loss factor tan can be respectively represented as s E T E eq s T, loss odulus n non E T (S5A) 1 1 T

11 T T n non E El T 11 (S5B) El T tan E T (S5C) where is the test frequency. Eploying the nonlinear regression (NLREG) ethod (4), s non R E,, C 1, C and AFc/k can be deterined by fitting the storage odulus and tan curves shown in fig. S1A and B. The fitted paraeters are listed in table S1. For the elastoer, it is seen fro fig. S1A that the storage odulus is alost teperature-independent above roo teperature. So for siplicity, a linear elastic odel is used to describe the rubber aterial where E elas is the elastic odulus and int y E e total e theral e pr ing, (S6) elas elas elas elas elas total e elas, theral e elas, e are the total strain, theral strain ( elas T ) pr int ing elas and printing bulid-in strain of the elastoer, respectively.

12 table S1. List of paraeters for constitutive odel. Branch non R E (Pa) (s) Branch non R E (Pa) (s) E+08.00E E E E E E E E E E E E E E E E E E E E E E E E E E E eq E S 6E+06 AF (Pa) c/k C T ( ) C S (/ ) 1.7E-4 E elas (Pa) 0.6E+06 elas (/ ).3E-4