Challenges for polymers

Although chemical engineering challenges related to polymeric materials are discussed in Chapter 5, the special challenges for polymers in materials and devices for iirformation storage and handling deserve some mention here. 

The requirements outlined above represent a considerable challenge for polymer synthesis. This article describes an appealing development, based on two central substance-classes of conjugated polymers, poly(para-phenylene)s and poly(para-phenylenevinylene)s. 

On one hand, the ionic conductor was unique in creating dynamic junction in LEC. On the other hand, the slow ionic motion and irreversibly electrochemical doping under high biasing field were two of the challenges for polymer LECs to be used in practical applications. More recent works have been focusing on the following directions ... 

Kiesewetter MK, Shin EJ, Hedrick JL, Waymouth RM (2010) Organocatalysis opportunities and challenges for polymer synthesis. Macromolecules 43 2093-2107... 

A HE CHARACTERIZATION OF MODERN HIGH-PERFORMANCE POLYMERS is still a challenge for polymer scientists. Copolymers and complex polymer blends play an important role in many applications (i). A fast, reliable, and comprehensive method is needed to succeed in this task. Size-exclusion chromatography (SEC) is a standard method for the determination of molar mass distributions (MMDs) and molecular weights, if... 

To be successful in these applications, it is important that materials can self-assemble into precisely defined structures. Peptide polymers have many advantages over conventional synthetic polymers since they are able to hierarchically assemble into stable ordered conformations [4]. Depending on the amino acid side chain substituents, polypeptides are able to adopt a multitude of conformationally stable regular secondary structures (helices, sheets, turns), tertiary structures (e.g. the /J-slrand-helix-/J-strand unit found in /1-barrels), and quaternary assembhes (e.g. collagen microfibrils) [4], The synthesis of polypeptides that can assemble into non-natural structures is an attractive challenge for polymer chemists. 

One of the greatest challenges for polymer transistors is to fabricate an ultrathin defect-free dielectric layer that also has a high-quality interface with the adjacent semiconductive layer. This dielectric layer has to show high dielectric breakdown strength, very low electrical conductivity, very low interface and bulk trapping of carriers, and good stability. 

Several transport properties can be evaluated from equilibrium simulations with use of linear response theory, which relates correlation fimctions of spontaneously fluctuating molecular properties to phenomenological transport coefficients. These relations can be used to evaluate diffusion coefficients, thermal conductivities, viscosities, IR spectra, and so on. However, most of these properties are evaluated more directly using appropriately devised techniques of nonequilibrium molecular dynamics. Particularly challenging for polymers is the direct... 

Recent advances in polymerization techniques have made possible the synthesis of complex, including hierarchically branched, maaomolecules with perfectly controlled architecture. Analysis of interplay between complex maaomolecular topology and multiple competing interactions on conformations, routes of self-organization in solutions and at interfaces, and properties of resulting supramolecular stractures presents a major cuuent and future challenge for polymer theory. 

Interest in natural fibers obtained from different resources to reinforce polymer so as to get the novel composites is growing rapidly because they are renewable, cheap, recyclable, and biodegradable. Research in this field has prompted surface modification of natural fibers in order to improve the compatibility between hydrophilic fibers and hydrophobic matrix [1], Major challenges for polymer scientists in the development of structural natural fiber-reinforced composites are to increase the moisture resistance, dimensional stability with minimized matrix material, and to decrease the manufacture costs of the composite materials. Different researchers have used different surface modification methods, that is, mercerization [2], benzoylation [3], silanation [4], acetylation [5], graft... 

Erben, Christoph, New Materials in Optoelectronics Advantages and Challenges for Polymers, Second Optoelectronics Packaging Workshop, Austin,TX, August 21 22,2001, pp. Bl- B22. 

The preparation of cyclic polymers has been particularly challenging for polymer chemists as the vast majority of polymerization methods involve the linear propagation from an initiator to a terminal end group. A post... 

Greco, F. and Vicent, M.J. (2009) Combination therapy Opportunities and challenges for polymer-drug conjugates as anticancer nanomedicines Adv Drug Deliv Rev, 61,1200-1213. 

Special emphasis is paid to a modular approach in which functionalized benzene moieties serve as building blocks for chain-type (ID), disc-type (2D), and dendrimer-type (3D) graphene derivatives (Fig. 1) [104,105]. The critical question, when taking on graphene as a challenge for polymer synthesis, is whether any of these polyphenylenes can serve as precursors for graphenes and how the necessary chemical transformation to flat graphene sheets can be accomplished. 

The syntheses of graphene nanoribbons and the troublesome problems of keeping the products solution-processable will continue to define challenges for polymer chemistry, but have also suggested another, somewhat unconventional, approach. In a fruitful interaction with the group of Roman Fasel, who are focused on the surface physics and STM detection [213-216] under UHV conditions, we deposited dihalo-substituted, non-planar oligophenylene compounds as precursor... 

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