Issues macromolecules

M. Schuster, C.C. de Araujo, V. Atanasov, H.T. Andersen, K.-D. Kreuer, J. Maier, Highly sulfonatedpoly(phenylene sulfone) Preparation and stability issues. Macromolecules 2009, 42(8), 3129-3137. 

Schuster M, de Araujo CC, Atanasov V, Andersen HT, Kreuer KD, Maier J. Highly sulfonated polyCphenylene sulfone) preparation and stability issues. Macromolecules 2009 42(8) 3129-37. 

Schuster, M., de Araujo, C. C., Atanasov, V., Andersen, H. T., Kreuer, K. D., and Maier, J. 2009. Highly sulfonated poly(phenylene sulfone) Preparation and stahUity issues. Macromolecules 42 3129-3137. 

It is clear that, having the same chain length, these macromolecules are in reality experimentally indistinguishable. One could however think of a labelling technique to make Nf different from Nj, for example by using a chromophore-bound radical scavenger which added selectively to the macroradicals issued from the chain scission. Equation (87) can be split into a system of two equations (100) and (101)... 

Therefore, it is a very relevant issue the evaluation of molecules and macromolecules that can efficiently act as quenchers of electronically excited states, such as 3RF and 1O2 as examples, to avoid the formation of ROS and/or eliminate them (Wondrak et al., 2006). 

The overall objective of this chapter is to review the fundamental issues involved in the transport of macromolecules in hydrophilic media made of synthetic or naturally occurring uncharged polymers with nanometer-scale pore structure when an electric field is applied. The physical and chemical properties and structural features of hydrophilic polymeric materials will be considered first. Although the emphasis will be on classical polymeric gels, discussion of polymeric solutions and nonclassical gels made of, for example, un-cross-linked macromolecular units such as linear polymers and micelles will also be considered in light of recent interest in these materials for a number of applications... 

To answer Staudinger s critics, Carothers knew he had to resolve three issues. First, he would have to build one of Staudinger s macromolecules. Next, he would have to confirm that they were indeed long-chained molecules, not merely aggregates of smaller molecules, as others claimed. Finally, he would have to prove that the forces holding the chains together were ordinary valence bonds, rather than a mysterious weak force. 

Mackerell AD (2004) Empirical force fields for biological macromolecules Overview and issues. J Comput Chem 25(13) 1584-1604... 

This chapter draws a comprehensive picture of what has been done in the field of dendrimers with polymeric cores putting emphasis first on synthetic issues and then on experiments investigating the aggregation behavior of these intruiging macromolecules both in the solid state and on surfaces. Additionally, experiments will be described which show that some of these dendrimers can be considered cylindrical molecular objects. The macromolecules treated in this chapter may be considered as either dendrimers with polymeric core or alternatively dendronized polymers (or polymers with appendent dendrons) depending on whether one sees them from the vantage point of an organic or macromolecular chemist. 

Yoon DY, Flory PJ (eds) (1979) Special issue on the organization of macromolecules in the condensed phase. Faraday Discuss. Chem Soc 68 7... 

A very important question in the context of dendrimers and their utility as host molecules relates to the existence of cavities within these macromolecules. The presence of internal voids in dendrimers is closely related to their conformational behaviour and to the degree of back-folding of the terminal branches into the interior of the dendrimer. The issue of back folding was already briefly touched upon in section 16.2.1. Next to the purely theoretical calculations mentioned there, several calculations have been performed on specific dendrimer types. 

Many drugs are administered as parenterals for speed of action because the patient is unable to take oral medication or because the drug is a macromolecule such as a protein that is unable to be orally absorbed intact due to stability and permeability issues. The U.S. Pharmacopoeia defines parenteral articles as preparations intended for injection through the skin or other external boundary tissue, rather than through the alimentary canal. They include intravenous, intramuscular, or subcutaneous injections. Intravenous injections are classified as small volume (<100 mL per container) or large volume (>100 mL per container) injections. The majority of parenteral dosage forms are supplied as ready-to-use solutions or reconstituted into solutions prior to administration. Suspension formulations may also be used,101 although their use is more limited to a subcutaneous (i.e., Novolin Penfill NOVO Nordisk) or intramuscular (i.e., Sandostatin LAR Depot Novartis) injection. Intravenous use of disperse systems is possible but limited (i.e., Doxil Injection Ortho Biotec). 

The first publication of the lUPAC in the area of macromolecular nomenclature was in 1952 by the Sub-commission on Nomenclature of the then lUPAC Commission on Macromolecules, which drew on the talents of such remarkable individuals as J. J. Hermans, M. L. Huggins, O. Kratky, and H. F. Mark. That report [1] was a landmark in that, for the first time, it systematized the naming of macromolecules and certain symbols and terms commonly used in polymer science. It introduced the use of parentheses in source-based polymer names when the monomer from which the polymer is derived consists of more than one word, a practice that is now widely followed, and it recommended an entirely new way of naming polymers based on their structure that included the suffix amer , a recommendation that has been almost totally ignored. After ten years, the Sub-commission issued its second report [2], which dealt with the then-burgeoning field of stereoregular polymers. A revision [3] of definitions in the original report appeared four years later. In 1968, a summary report [4] of the activities of the Subcommission was published. 

There are a number of limitations on the use of extremes of temperature in HPLC. Clicq et al. [91] note that instrumental issues become increasingly limiting as one goes to very high temperatures and flow rates. They suggest that most separations will occur below 90°C where there are less instrumental constraints. As detailed below, column bleed can limit the selection of columns. Highspeed separations require a faster detector response than many systems allow and constrain extra column volume. This is especially true for narrow bore columns and sub-2 jam particles. In many cases, the additional speed gained above the temperature limits of commercial HPLC ovens will not be worth the additional expense and complexity required. For macromolecules, the effect of extreme pressure can also impact retention time as noted by Szabelski et al. [92]. 

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