The total thickness of a graphene sample depends upon the number of individually stacked graphene layers. The corresponding surface plasmon resonance (SPR) reflectance alters the SPR angle, depending on the number of graphene layers. Thus, the correlation between the SPR angle shift and the number of graphene layers allows for a nonintrusive, real-time, and reliable counting of graphene layers. A single-layer graphene (SLG) is synthesized by means of chemical vapor deposition, followed by physical transfer to a thin gold film (48 nm) repeatedly, so that multilayer graphene samples with one, three, and five layers can be prepared. Both the measured SPR angles and the entire reflectance curve profiles successfully distinguish the number of graphene layers.
Polymer foams are expanding their applications into functional materials. Partial foam structure has been fabricated in polyethylene terephthalate–polyethylene naphthalate (PET–PEN) copolymer by solid state foaming. Through SEM image analyses, a potential to fabricate gradient foam structures with micropores and unfoamed skin layers has been identified. The post-foaming temperature Tf tune the pore size distribution. Radial distribution of micromechanical properties, indentation hardness and elastic modulus were measured for the partial foam and their values were around 0.12 GPa and 2.0 GPa, respectively, for the outer foamed region. Foaming temperature affects the glass transition temperature Tg, the coefficient of thermal expansion and the flame spreading rate. For the range of Tf ≤ 60°C, thermal expansion coefficients for T> Tg are about 0.5 m/m°C (steep expansion group, SEG). When Tf is above 80 °C, they are around 0.02 m/m°C (mild expansion group, MEG). The burning rate of SEG is 2.8 times higher than that of MEG.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.