Researcher: Daniela Marques (MS&E Undergraduate)

Ultraviolet Responsive Polyurethanes with Variable Moduli Via Coumarin Moieties

A Path to Integration in Delicate Grasping Mechanisms for Humanoid Robotics


Daniela Marques, Erin Askounis, Qibing Pei

Sponsor: INTEL/ SRC Education Alliance


A polymer with ultraviolet (UV) responsive changes in stiff­ness can be utilized as a grasping mechanism for delicate objects

in humanoid robotics. A polymer synthesized using poly­ethylene glycol (PEG) (soft segment) with dihydroethoxy me­thyl

coumarin (DHEOMC) and hexamethylene diisocyanate (HMDI) (hard segment) exhibits a change in elastic modulus

after UV exposure.When exposed to long-wave UV (365 nm), crosslinking occurs – stiffening the polymer; short-wave

UV (254 nm) exposure reverses the reaction. Varying molecular weights of PEG (Mn = 200 and 400 g/mol) yields


poly­mers with different mechanical properties. The modulus changes in each polymer are

de­termined by dynamic mechanical analysis before and after exposure.

PEG200 demonstrated a larger modulus change after exposure than PEG400, due

to higher crosslinking density. The largest modulus change for PEG400 was 2.1-fold, while

                                          the PEG200 exhibited a 15-fold in­crease. Polymers exhibiting a large modulus increase

                                             is ideal for the enhancement of humanoid robot­ics.




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The CEED (Center for Excellence in Engineering and Diversity) Mission is to work with a community of partners to ensure equity and parity in the K-20 pathways that lead to engineering and computing degrees. CEED’s undergraduate retention approach offers numerous programs and services focused on the personal, academic, and career development of economically disadvantaged and underrepresented engineering and computing students at UCLA. The Research Intensive Series in Engineering for Underrepresented Populations (RISE-UP) is an undergraduate research program that started in 2005. RISE-UP provides academic year and summer research opportunities.