Artefacts made of polymers – “plastics” – are ubiquitous in our daily live, and polymers such as polyethylene, polypropylene or poly(ethylene terephthalate) have developed into multi-billion markets since their discovery some 80 years ago. Surprisingly, however, various, important aspects of these versatile materials are not understood, especially when used in blends. Processing them into useful products, especially of specific and/or multiple functions, is thus often directed by time-consuming, intricate trial-and-error approaches. The complexity result from the difficulty to characterize polymeric systems: they are of high molecular weight; they lack usually heavy atoms leading to low contrast between components; the feature a low stability, e.g. in electron beams, etc. Here we discuss pathways to gain understanding of the role of multiscale structure and phase behavior in determining the final properties and functions of multicomponent polymer blends. Starting with systems where reliable processing pathways towards specific features have been advanced, we discuss strategies towards a unifying structure/property picture for multifunctional architectures made of ‘plastics’ that can lead to a knowledge platform towards widely-applicable design rules for smart, plastic artefacts. We use as examples recent discoveries that addition of large fractions of an insulating bulk ‘plastics’ such as high-density polyethylene does not negatively affect charge transport of electrons or holes and that addition of the commodity polymer poly(ethylene oxide) allows manipulation of the overall aggregate character of the ubiquitous polymeric semiconductor poly(3-hexylthiophene). Similar observations have been made with higher efficiency plastics, such as poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3’’’-di(2-octyldodecyl)-2,2’;5’,2’’;5’’,2’’’-quaterthiophen-5,5’’’-diyl)] (PCE11). We will show that combining classical polymer science tools with well-established and recently developed, characterization techniques can be used to identify design- and processing criteria for functional polymer blends towards specific functions by unveiling the relevant structural features on all length scales that make specific blends work and give some materials discovery and will permit to start with the creation of a materials database for macromolecular blends.

Plastic semiconductors: How we can exploit blending to manipulate functions?

255th National Meeting (2018)

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