@article{mailen_wagner_bang_zikry_dickey_genzer_2019, title={Thermo-mechanical transformation of shape memory polymers from initially flat discs to bowls and saddles}, volume={28}, ISSN={["1361-665X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85065648786&partnerID=MN8TOARS}, DOI={10.1088/1361-665X/ab030a}, number={4}, journal={SMART MATERIALS AND STRUCTURES}, author={Mailen, Russell W. and Wagner, Catherine H. and Bang, Rachel S. and Zikry, Mohammed and Dickey, Michael D. and Genzer, Jan}, year={2019}, month={Apr} }
 @article{cooper_joshipura_parekh_norkett_mailen_miller_genzer_dickey_2019, title={Toughening stretchable fibers via serial fracturing of a metallic core}, volume={5}, ISSN={["2375-2548"]}, url={https://doi.org/10.1126/sciadv.aat4600}, DOI={10.1126/sciadv.aat4600}, abstractNote={Stretchable fibers dissipate energy via the sequential fracturing of a metallic core held together by an elastomeric shell.}, number={2}, journal={SCIENCE ADVANCES}, publisher={American Association for the Advancement of Science (AAAS)}, author={Cooper, Christopher B. and Joshipura, Ishan D. and Parekh, Dishit P. and Norkett, Justin and Mailen, Russell and Miller, Victoria M. and Genzer, Jan and Dickey, Michael D.}, year={2019}, month={Feb} }
 @article{mailen_dickey_genzer_zikry_2017, title={A fully coupled thermo-viscoelastic finite element model for self-folding shape memory polymer sheets}, volume={55}, ISSN={["1099-0488"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85019544264&partnerID=MN8TOARS}, DOI={10.1002/polb.24372}, abstractNote={The thermo-mechanical response of heat activated shape memory polymers (SMPs) has been investigated using a thermo-viscoelastic finite element analysis that accounts for external and internal heat sources. SMPs can be thermally stimulated by external heat sources, such as temperature and surface heat flux, or from internal viscous heating. Viscous heating can significantly affect the response of SMP sheets by increasing the temperature during pre-strain, which accelerates stress relaxation. This stress relaxation results in a slower shrinking rate when the SMP is reheated. Viscous heating also causes an increase in temperatures during unconstrained recovery. The predicted results elucidate how the coupled thermo-mechanical loading conditions affect folding and unfolding of SMP sheets in response to localized heating in a hinged region. A parametric study of sheet thickness, hinge width, degree of pre-strain, and hinge surface temperature is also conducted. The validated results can provide guidelines for the design of functional, self-folding structures. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017}, number={16}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, publisher={Wiley}, author={Mailen, Russell W. and Dickey, Michael D. and Genzer, Jan and Zikry, Mohammed A.}, year={2017}, month={Aug}, pages={1207–1219} }
 @article{mailen_dickey_genzer_zikry_2017, title={Effects of thermo-mechanical behavior and hinge geometry on folding response of shape memory polymer sheets}, volume={122}, ISSN={["1089-7550"]}, url={https://doi.org/10.1063/1.5000040}, DOI={10.1063/1.5000040}, abstractNote={Shape memory polymer (SMP) sheets patterned with black ink hinges change shape in response to external stimuli, such as absorbed thermal energy from an infrared (IR) light. The geometry of these hinges, including size, orientation, and location, and the applied thermal loads significantly influence the final folded shape of the sheet, but these variables have not been fully investigated. We perform a systematic study on SMP sheets to fundamentally understand the effects of single and double hinge geometries, hinge orientation and spacing, initial temperature, heat flux intensity, and pattern width on the folding behavior. We have developed thermo-viscoelastic finite element models to characterize and quantify the stresses, strains, and temperatures as they relate to SMP shape changes. Our predictions indicate that hinge orientation can be used to reduce the total bending angle, which is the angle traversed by the folding face of the sheet. Two parallel hinges increase the total bending angle, and heat con...}, number={19}, journal={JOURNAL OF APPLIED PHYSICS}, publisher={AIP Publishing}, author={Mailen, Russell W. and Dickey, Michael D. and Genzer, Jan and Zikry, Mohammed}, year={2017}, month={Nov} }
 @article{morales_podolsky_mailen_shay_dickey_velev_2016, title={Ionoprinted Multi-Responsive Hydrogel Actuators}, volume={7}, ISSN={["2072-666X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84982797733&partnerID=MN8TOARS}, DOI={10.3390/mi7060098}, abstractNote={We report multi-responsive and double-folding bilayer hydrogel sheet actuators, whose directional bending response is tuned by modulating the solvent quality and temperature and where locally crosslinked regions, induced by ionoprinting, enable the actuators to invert their bending axis. The sheets are made multi-responsive by combining two stimuli responsive gels that incur opposing and complementary swelling and shrinking responses to the same stimulus. The lower critical solution temperature (LCST) can be tuned to specific temperatures depending on the EtOH concentration, enabling the actuators to change direction isothermally. Higher EtOH concentrations cause upper critical solution temperature (UCST) behavior in the poly(N-isopropylacrylamide) (pNIPAAm) gel networks, which can induce an amplifying effect during bilayer bending. External ionoprints reliably and repeatedly invert the gel bilayer bending axis between water and EtOH. Placing the ionoprint at the gel/gel interface can lead to opposite shape conformations, but with no clear trend in the bending behavior. We hypothesize that this is due to the ionoprint passing through the neutral axis of the bilayer during shrinking in hot water. Finally, we demonstrate the ability of the actuators to achieve shapes unique to the specific external conditions towards developing more responsive and adaptive soft actuator devices.}, number={6}, journal={MICROMACHINES}, publisher={MDPI AG}, author={Morales, Daniel and Podolsky, Igor and Mailen, Russell W. and Shay, Timothy and Dickey, Michael D. and Velev, Orlin D.}, year={2016}, month={Jun} }
 @article{mailen_liu_dickey_zikry_genzer_2015, title={Modelling of shape memory polymer sheets that self-fold in response to localized heating}, volume={11}, ISSN={["1744-6848"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84943141129&partnerID=MN8TOARS}, DOI={10.1039/c5sm01681a}, abstractNote={We conduct a nonlinear finite element analysis (FEA) of the thermo-mechanical shrinking and self-folding behavior of pre-strained polystyrene polymer sheets.}, number={39}, journal={SOFT MATTER}, publisher={Royal Society of Chemistry (RSC)}, author={Mailen, Russell W. and Liu, Ying and Dickey, Michael D. and Zikry, Mohammed and Genzer, Jan}, year={2015}, pages={7827–7834} }