The Max Planck Institute for Polymer Research is a scientific center in the field of polymer science located in Mainz, Germany. The institute was founded in 1983 by Erhard W. Fischer and Gerhard Wegner. Belonging to the Chemistry, Physics and Technology Section, it is one of the 80 institutes in the Max Planck Society . Wikipedia.
Kunz A.,Max Planck Institute for Polymer Research
Nature Materials | Year: 2016
In 1962, Mark and Helfrich demonstrated that the current in a semiconductor containing traps is reduced by N/Nt r, with N the amount of transport sites, Nt the amount of traps and r a number that depends on the trap energy distribution. For r > 1, the possibility opens that trapping effects can be nearly eliminated when N and Nt are simultaneously reduced. Solution-processed conjugated polymers are an excellent model system to test this hypothesis, because they can be easily diluted by blending them with a high-bandgap semiconductor. We demonstrate that in conjugated polymer blends with 10% active semiconductor and 90% high-bandgap host, the typical strong electron trapping can be effectively eliminated. As a result we were able to fabricate polymer light-emitting diodes with balanced electron and hole transport and reduced non-radiative trap-assisted recombination, leading to a doubling of their efficiency at nearly ten times lower material costs. © 2016 Nature Publishing Group
Mullen K.,Max Planck Institute for Polymer Research
ACS Nano | Year: 2014
The evolution of nanoscience is based on the ability of the fields of chemistry and physics to share competencies through mutually beneficial collaborations. With this in mind, in this Perspective, I describe three classes of compounds: rylene dyes, polyphenylene dendrimers, as well as nanographene molecules and graphene nanoribbons, which have provided a superb platform to nurture these relationships. The synthesis of these complex structures is demanding but also rewarding because they stimulate unique investigations at the single-molecule level by scanning tunneling microscopy and single-molecule spectroscopy. There are close functional and structural relationships between the molecules chosen. In particular, rylenes and nanographenes can be regarded as honeycomb-type, discoid species composed of fused benzene rings. The benzene ring can thus be regarded as a universal modular building block. Polyphenylene dendrimers serve, first, as a scaffold for dyes en route to multichromophoric systems and, second, as chemical precursors for graphene synthesis. Through chemical design, it is possible to tune the properties of these systems at the single-molecule level and to achieve nanoscale control over their self-assembly to form multifunctional (nano)materials. © 2014 American Chemical Society.
Spiess H.W.,Max Planck Institute for Polymer Research
Macromolecules | Year: 2010
In recent years major advances in generating, characterizing, and understanding macromolecular and supramolecular systems have been achieved. This has led to an enormous variety and complexity in polymer science. The traditional separation in terms of structure vs dynamics, crystalline vs amorphous, or experiment vs theory is increasingly overcome. As far as characterization of such materials is concerned, no experimental or theoretical/simulation approach alone can provide complete information. Instead, a combination of techniques is called for, and conclusions should be supported by results provided by complementary techniques. This Perspective discusses the kind of information that can be obtained by advanced solid state NMR and EPR spectroscopy, combined and/or compared with X-ray and neutron scattering as well as dielectric spectroscopy and computer simulation. The multi-technique approach is demonstrated by a number of examples including morphology, defects, heterogeneities in time scale and amplitude of motion, and local and collective dynamics in polymers of different architectures, biomacromolecules, and hybrid systems. © 2010 American Chemical Society.
Figueira-Duarte T.M.,BASF |
Mullen K.,Max Planck Institute for Polymer Research
Chemical Reviews | Year: 2011
Pyrene's unique properties have inspired researchers from many scientific areas, making pyrene the chromophore of choice in fundamental and applied photochemical research. There has been an increased interest in the use of pyrene as organic semiconductor for application in materials science and organic electronics. Modification of the chemical structure by varying the substitution at different positions of the pyrene ring allows the control of the molecular architecture and thus the molecular packing, which renders the handling of pyrene substitution a key factor in pyrene-based semiconductors. Pyrene, as a blue-light-emitting chromophore with good chemical stability and high charge carrier mobility, appears to be a very attractive building block for light-emitting devices. The electrooptical properties of pyrene can be fine-tuned by introducing specific electron-donating or -accepting groups or, alternatively, by simply modifying the molecular architecture via substitution at the pyrene ring.
Hinderberger D.,Max Planck Institute for Polymer Research
Topics in Current Chemistry | Year: 2012
Synthetic polymers belong to the vast realm of soft matter and are one of the key types of materials to address societal needs at the beginning of the twenty-first century. Polymer science progressively addresses questions that deal with tuning mesoscopic and macroscopic structures and functions of polymers by understanding the effects that govern these systems on the nanoscopic level. EPR spectroscopy as a local, sensitive, and extremely specific magnetic resonance technique in many cases shows sensitivity on well-suited length-(0-10 nm) and time scales (μs-ps) and can deliver unique information on structure, dynamics, and in particular function of polymeric systems. A short review of recent literature is given and the power of simple EPR methods, especially CW EPR performed on a low-cost benchtop spectrometer, to elucidate complex polymeric materials is shown with specific examples from thermoresponsive polymer systems. These bear great potential in molecular transport and biomedical applications (e.g., drug delivery) and insights into interactions between carrier and small molecule are fundamental for designing and tuning these materials. © 2011 Springer-Verlag Berlin Heidelberg.