Field Of Polymer Research Research Articles

Combinatorial methods and high-throughput experimentation in synthetic polymer chemistry

ABSTRACTCombinatorial chemistry has revolutionized the drug discovery as well as the catalyst discovery and optimization process during the last years. Nowadays, triggered by these developments, combinatorial methods and parallel chemistry also emerge in the field of material and polymer chemistry. Especially the field of polymer research seems to be perfectly suited for these approaches since many parameters can be varied during synthesis, processing, blending, formulation and compounding. Moreover, the screening of interesting parameters, such as molecular weight, polydispersity, polymerization kinetics, viscosity, hardness or stiffness, became feasible only recently.Within this contribution we will describe our strategy to construct a most efficient workflow in the field of combinatorial polymer research. New developments made by our group as well as some general aspects will be discussed.

Combinatorial Methods, Automated Synthesis and High‐Throughput Screening in Polymer Research: Past and Present

AbstractCombinatorial techniques, parallel experimentation and high‐throughput methods represent a very promising approach in order to speed up the preparation and investigation of new polymeric materials: a large variety of parameters can be screened simultaneously resulting in new structure/property relationships. The field of polymer research seems to be perfectly suited for parallel and combinatorial methods due to the fact that many parameters can be varied during synthesis, processing, blending as well as compounding. In addition, numerous important parameters have to be investigated, such as molecular weight, polydispersity, viscosity, hardness, stiffness and other application‐specific properties. A number of corresponding high‐throughput techniques have been developed in the last few years and their introduction into the commercial market further boosted the development. These combinatorial approaches can reduce the time‐to‐market for new polymeric materials drastically compared to traditional approaches and allow a much more detailed understanding of polymers from the macroscopic to the nanoscopic scale. Here we provide an overview of the present status of combinatorial and parallel polymer synthesis and high‐throughput screening.magnified image

Dynamic mingling of magma and liquefied sediments

Hydrodynamic mingling of magma and liquefied sediments is generally accepted to represent the key process in the formation of some peperites. Experimental studies on simulant liquids and calculations based on recent empirical findings in the field of polymer research were undertaken to investigate the effectiveness of this process. These studies show that for a wide range of shear rates a laminar flow behaviour of the system magma–liquefied sediment can be expected, i.e. turbulent mingling is not a realistic scenario. Formation of peperitic fabrics with grain sizes on a cm scale can hydrodynamically be explained under realistic intrusion velocities. In addition to the hydrodynamics, cooling processes must also be considered during peperite formation. Calculations of the cooling history of the juvenile magmatic component under realistic cooling conditions demonstrate a significant limitation of the hydrodynamic mingling time. The consequence for peperite formation under normal intrusion conditions is that domains of magmatic melt and domains of liquefied sediment smaller than 10 cm are not probable. However, as smaller domain sizes (peperitic grain sizes) exist in nature, we conclude that either those peperites represent the products of explosive events or that hydrodynamic mingling was accompanied by additional fragmentation processes.

Crystalline Atactic Polymers

Abstract Within the field of polymer research, the investigation of crystalline polymers has proved to be useful from both a practical and a more fundamental point of view. Concerning the practical point, crystallinity strongly influences such mechanical properties of polymers as density, elastic modulus, tensile strength, and impact resistance. Concerning the more fundamental viewpoint, crystallinity and in particular the crystallization process seem to be not totally understood, and these topics have therefore been the subject of many theoretical considerations and speculations.

Fluorescence methods in polymer science

AbstractVarious aspects of the application of fluorescence characteristics in the field of polymer research are described. The polarization characteristics of fluorescence, that is, the angular distribution of the intensity of the polarized component, are indicative of the distribution patterns of fluorescent molecules in the medium. This principle can be utilized for the investigation of molecular orientation behavior in polymer solids. Examples are given for the molecular orientation behaviors during the deformation of poly(vinyl alcohol) and polypropylene films. The phenomenon of rotational depolarization of fluorescence is applied to the measurement of micro‐Brownian motions of polymer chains and the local viscosity of polymer solutions and melts. The internal structure of concentrated poly(styrene) solutions and the molecular motions in the melts of n‐paraffins and polyethylene homologs are discussed. Rotational relaxation time ranging from 10−12 to 10−5 sec can be measured by this method by using the lifetime of excitation of fluorescent groups as the reference time scale. The phenomenon of the excimer fluorescence emitted from the excited dimer provides a new method for studying molecular configuration and conformation of polymer molecules. Examples are given for the case of naphthalenecontaining polymers. The sequence of monomeric units in copolymers of vinylnaphthalene and styrene are studied from the intensity of excimer fluorescence relative to that of ordinary fluorescence from the naphthalene groups. The intramolecular excimer formations of polymer molecules are also discussed in relation to molecular motions.

Fluorescence methods in polymer science

Various aspects of the application of fluorescence characteristics in the field of polymer research are described. The polarization characteristics of fluorescence, that is, the angular distribution of the intensity of the polarized component, are indicative of the distribution patterns of fluorescent molecules in the medium. This principle can be utilized for the investigation of molecular orientation behavior in polymer solids. Examples are given for the molecular orientation behaviors during the deformation of poly(vinyl alcohol) and polypropylene films. The phenomenon of rotational depolarization of fluorescence is applied to the measurement of micro-Brownian motions of polymer chains and the local viscosity of polymer solutions and melts. The internal structure of concentrated poly(styrene) solutions and the molecular motions in the melts of n-paraffins and polyethylene homologs are discussed. Rotational relaxation time ranging from 10−12 to 10−5 sec can be measured by this method by using the lifetime of excitation of fluorescent groups as the reference time scale. The phenomenon of the excimer fluorescence emitted from the excited dimer provides a new method for studying molecular configuration and conformation of polymer molecules. Examples are given for the case of naphthalenecontaining polymers. The sequence of monomeric units in copolymers of vinylnaphthalene and styrene are studied from the intensity of excimer fluorescence relative to that of ordinary fluorescence from the naphthalene groups. The intramolecular excimer formations of polymer molecules are also discussed in relation to molecular motions.