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Contemporary strategies in STEM education focus on developing pedagogies that more actively engage students in their own learning. A method that has proven effective to this end has been peer instruction and discussion, particularly those in which participating students must organize information in such a way as to be able to verbally articulate it to others. The success of peer learning raises the question of what other communicative activities could lead to similar learning gains. Writing is a reasonable choice for such an activity, as there is strong historical evidence of the value of writing in facilitating student learning. Presented here is "writing-to-teach"; a fusion of writing and peer instruction that is rooted in the theories of meaningful learning and situated cognition as well as research on student-generated explanatory knowledge. Writing-to-teach activities were designed and implemented in an introductory physical chemistry course and evaluated using student surveys. In addition, a novel expert-ranking methodology was employed to evaluate the quality of explanatory writing produced by students engaging in writing-to-teach activities. Lastly, suggestions are given on how writing-to-teach can be implemented more broadly in other STEM classrooms.

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Flip chip technology has greatly improved the performance of semiconductor devices, but relies heavily on the performance of epoxy underfill adhesives. Because epoxy underfills are cured in situ in flip chip semiconductor devices, understanding their surface and interfacial structures is critical for understanding their adhesion to various substrates. Here, sum frequency generation (SFG) vibrational spectroscopy was used to study surface and buried interfacial structures of two model epoxy resins used as underfills in flip chip devices, bisphenol A digylcidyl ether (BADGE) and 1,4-butanediol diglycidyl ether (BDDGE). The surface structures of these epoxies were compared before and after cure, and the orientations of their surface functional groups were deduced to understand how surface structural changes during cure may affect adhesion properties. Further, the effect of moisture exposure, a known cause of adhesion failure, on surface structures was studied. It was found that the BADGE surface significantly restructured upon moisture exposure while the BDDGE surface did not, showing that BADGE adhesives may be more prone to moisture-induced delamination. Lastly, although surface structure can give some insight into adhesion, buried interfacial structures more directly correspond to adhesion properties of polymers. SFG was used to study buried interfaces between deuterated polystyrene (d-PS) and the epoxies before and after moisture exposure. It was shown that moisture exposure acted to disorder the buried interfaces, most likely due to swelling. These results correlated with lap shear adhesion testing showing a decrease in adhesion strength after moisture exposure. The presented work showed that surface and interfacial structures can be correlated to adhesive strength and may be helpful in understanding and designing optimized epoxy underfill adhesives.

Silane adhesion promoters are commonly used to enhance the adhesion of elastomeric materials to polymers in many industrial applications. However, it is difficult to study the molecular-level mechanisms underlying adhesion promotion because adhesion occurs at the boundary between two layers, a buried interface that is difficult to probe with most techniques. Here, a surface/ interface-sensitive optical technique, sum frequency generation vibrational spectroscopy, was used to probe the buried interfaces between the silicone elastomer and (3-glycidoxypropyl)trimethoxysilane (γ-GPS) as well as a known silane adhesion-promoting mixture of γ-GPS and methylvinylsiloxane (MVS). The γ-GPS methoxy groups were found to order at the silicone interface both in the neat silane and in the mixture with MVS. The interfacial structures between the silicone elastomer and two other silanes not used as adhesion promoters, n-octadecyltrimethoxysilane (OTMS) and (tridecafluoro-1,1,2,2-tetrahydrooctyl)trimethoxysilane (TDFTMS), and their mixtures with MVS, were also compared to those of γ-GPS and the γ-GPS/MVS mixture. It was found that these silanes behaved differently than the known adhesion-promoting mixture. Further, molecular dynamics simulations confirmed that all silanes showed broad, random orientation distributions at the silicone interface. Because only the known adhesion-promoting mixture of γ-GPS and MVS exhibited methoxy order at the silicone interface, as well as at the poly(ethylene terephthalate) interface, as shown in a previous publication, it is inferred that this ordering may be a necessary condition for adhesion promotion.