Better Recyclable Rubbers: Thermoplastic Elastomers Richard A. Register, Princeton University, DMR Conventional rubbers get their strength from “vulcanization” (crosslinking)– but once a material is vulcanized, it cannot be reshaped or recycled. “Thermoplastic elastomers” (TPEs) behave like vulcanized rubbers at room temperature, but are easily shaped at high temperatures. A major drawback of most TPEs is that they dissolve in common organic liquids, and cannot be used in applications such as gaskets and hoses. Incorporating crystallinity into the material gives it solvent resistance, but at the price of making it less resilient– the principal quality sought in a rubber. Recently, we 1 synthesized a TPE which has crystallizable, glassy, and rubbery segments, balanced so as to capture the most desirable qualities of each, yielding a soft, resilient rubber, shaped with very low energy input when hot, yet insoluble in solvents. We are now exploring the range of properties possible with such polymers. [1] J.P. Bishop and R.A. Register, “Thermoplastic Elastomers with Composite Crystalline-Glassy Hard Domains and Single-Phase Melts”, Macromolecules, 43, (2010). Top: Chemical structures of the monomers which form the blocks in our new TPEs; at room temperature, these blocks are crystalline (blue), glassy (green), and rubbery (red). Bottom: At elevated temperatures, all three types of block are intimately mixed, but when cooled (right), the blue block crystallizes, and drags with it the glassy green block forming composite crystalline-glassy hard domains that anchor the rubbery red blocks, while resisting both mechanical deformation and attack by solvents.

Week-Long Camp Teaches Materials Science to High School Teachers Richard A. Register, Princeton University, DMR Each year since 2005, Princeton has run a week-long materials science teacher training camp, in partnership with ASM (The Materials Information Society). Coordinated by the DMR- supported Princeton Center for Complex Materials, each year our materials camp provides 30 teachers from New Jersey, Pennsylvania, and New York hands-on laboratory experiences, coupled with lectures on the fundamentals (including from Rick Register on “polymers”), all of which the teachers can use in their own classrooms. This year, a video describing the camp was posted on the Princeton University main webpage, as well as the NSF’s public science website, Science360. We hope that such publicity will excite others to try similar teacher training events elsewhere around the US. Shot from a video describing the Princeton materials science teacher training camp, interviewing Rick Register following his lecture about the aims of the camp. In the background is one of the slides from the lecture, showing an artist’s rendition of Charles Goodyear’s invention of “vulcanization”, the process which imparts dimensional stability to rubbers but also makes them impossible to reshape. The video is viewable on YouTube (“Princeton Materials Science Camp for Teachers”), on the Princeton University main webpage ( and on the NSF’s Science360 (news.science360.gov/files/video, July 20, 2010 issue).