Site-specific character

Site-specific delivery will require the use of a self-locating system, typically a bioadhesive formulation, although an IVR, due to its elastomeric nature, will remain located high in the vaginal space. Conversely, for rapid distribution throughout the space, semisolid or fast-dissolving solid systems will be required. For semisolids, flow properties and viscoelastic character will be the critical determinants of their ability to spread rapidly from their point of application. 

In summary, the attractive term of the adsorption energy consists of two commensurable contributions. The first is the electrostatic interaction. It has specific character. This interaction is responsible for the orientation of the absorbed nitroaromatic compounds. Another stabilizing interaction originates from dispersion energy. The dispersion interaction does not have a specific character. However, it has been found that significant part of the adsorption energy contributes to the specific interaction between TNB and the siloxane sites of clay minerals. 

A CRP is a free-radical polymerization that displays a living character, that is, does not terminate or transfer, and is able to continue polymerization once the initial feed is exhausted by the addition of a monomer. However, termination reactions are inherent to a radical process, and modern CRP techniques seek to minimize such reactions, thus providing control over molecular weight and molecular weight distribution. More sophisticated CRP approaches incorporate many of the desirable features of traditional free-radical polymerization, such as compatibility with a wide range of monomers, tolerance of many functionaHties, and facile reaction conditions. The control of molecular weight and molecular weight distribution has enabled access to complex architectures and site-specific functionality that were previously impossible to achieve via traditional free-radical polymerizations [35, 36]. 

Very few PPM chemistries provide the opportunity of incorporating two residues at the same site in a polymer. When established, the site-specific double PPM not only offers the possibility of introducing both residues, closely positioned at the molecular level, but also virtually guarantees introduction of the residues in equal amounts, provided both reactions reach full conversion. Therefore, the unique character of the thiolactone-based site-specific (one-pot) double modification approach is highlighted in the discussion below. Interestingly, three distinct chemical platforms allowing for site-specific double PPM have been very recently developed by Theato and coworkers [137-139]. 

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