Supporting Information

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1 PROTOCOL Supporting Information First Large-Scale Engineered Synthesis of BaTiO 3 Nanoparticles Using Low Temperature Bioinspired Principles 5 Teyeb Ould-Ely, a Matthew Luger a,b, Lyle Kaplan-Reinig, a,b Krisztian Niesz, a, Michael Doherty b and Daniel E. Morse a* a Institute for Collaborative Biotechnologies, California NanoSystems Institute, the Materials Research Laboratory, and the Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106, b Department of Chemical Engineering, University of California, Santa Barbara, CA , USA T

2 10 Fig. 1S: Reactor platform-1: two merged vessels. 15 Fig. 2S: Reactor platform-2 : two reactors separated by an M-shaped bridge.

3 Fig. 3S: Reactor platform-3 : reactor with internal vapor release device

4 40 Table 1 : Summary of reactor performances and optimization 45 Reactor Platform Product Yield & Quality Control Reaction time Design advantages & disadvantages g TEM shows agglomerated particles d<~6nm> ~ 48h at room temperature; accelerated by gentle heating Not practical for vigorous stirring with gentle heating. Vapor condenses on the internal roof of the vessel, allowing water to drip directly into the precursor solution (potentially leading to amorphization) g XRD and TEM show agglomerated particles d<~6nm> Reaction time and product quality differed for room temperature and heated (40-80 C) process 125 +/- 5g XRD and TEM show particles d<~6nm> 5-10 d 10g batches typically take 5 d; 50g batches require 10 d. Reaction can be accelerated by jacket heating and rapid stirring 24h when heated to C; 3 d at RT, with gente heating (60 C) following gellation; >10d at RT without gentle heating after gelation Vessels are separated by an M-bridge with a droplet trap cavity at the center. Waterjacketing controls kinetics of vapor diffusion through gentle heating. Due to the solid angle, rigid structure, and large space requirement, the design is immobile and difficult to handle. Design is optimized for batch reactions, but cannot be adapted for continuous flow. For continuous flow, the internal inset would need to be replaced by steam injectors or nebulizers. for increased, accurately measured vapor delivery. 75 Fig. 4S: Images of various batches obtained using the reactors designed above; (1-5g) using (1), (up to 50 g) using (2), and up to 125g using (3).

5 Mechanistic Investigations 80 1) Effect of concentration Fig. 5S : Mechanistic investigation of the effect of initial precursor concentration on final particle size. All other conditions (stirring rate, temperature, H 2 O vapor delivery rate) were held constant except the concentration (specified in torque data figures at left. Top Concentrated precursor; Middle as presented in main body of the paper; Bottom Dilute precursor. Both TEM (middle column) and XRD (right column) data confirm that the particle size remains in the range of 5-7 nm, although increasing slightly with initial precursor concentration: Mean particle diameter was ca. 7nm for the concentrated sample, 6nm for the normal sample, and 5.5nm for the dilute sample.

6 2) Effect of stirring rate 95 Figure 6S : Mechanistic investigation of the effect of stirring rate on the particle size. All other conditions (concentration, temperature, H 2 O vapor delivery rate) were held constant except 100 the stirring rate. Top 300rpm stirring; Middle 200rpm stirring; Bottom - 100rpm stirring. Torque data (left column) confirm that at the slowest stirring rate gelling is slow and heterogeneous in time, and that gelling becomes progressively faster and synchronous with faster stirring. Both TEM (middle column) and XRD (right colun) data confirm that the particle size remains unchanged (~6 nm) regardless of the stirring rate. XRD shows highly crystalline 105 samples with no impurities. 110

7 1) Effect of temperature Figure 7S : Mechanistic investigation of the effect of temperature on the particle size. All other conditions (concentration, stirring rate, H 2 O vapor delivery rate) are held constant except the temperature. Top: 80 ºC; Middle: 60 C; Bottom: 25 º C. The torque data (left column) confirm that at room temperature the gelling process is slow (up to 5-7 days for the gelling alone). When the temperature is increased to 60 ºC, the reaction time is shorter (24h to gelling and 12 h for aging). When the sample is heated to 80 ºC, the gelling point becomes diffuse but a slight increase of torque is noticed after 12h; subsequent aging for another 12h leads to final product. Both TEM (middle) and XRD data (right) confirm that the particle size remains unchanged (~6 nm) regardless of mild heating. XRD show highly crystalline samples with no impurities. 130

8 Fig. 8S: 250 g batch, XRD shows high crystallinity, pure BaTiO3, with a particle size of ~ nm. Similar result was observed by TEM.

9 Figure 9S: This configuration was also investigated, but was excluded due to considerable 140 heat necessary to transport and maintain the hydrolyzer in the vapor phase.

10 145 Figure 10S: An incomplete reaction is generally marked by the presence of a shoulder on the first peak (which disappears on gentle heating (60 or 80 C) of the sample, or upon leaving the process for extended period of time (>> 7 days). This shoulder cannot be assigned or quantified due to the peaks broadening and absence of extra-peaks (other than BaTiO 3 ).