Post-polymerization modification is based on the direct polymerization or copolymerization of monomers bearing chemoselective handles that are inert towards the polymerization conditions but can be quantitatively converted in a subsequent step into a broad range of other functional groups. The success of this method is based on the excellent conversions achievable under mild conditions, the excellent functional-group tolerance, and the orthogonality of the post-polymerization modification reactions. This Review surveys different classes of reactive polymer precursors bearing chemoselective handles and discusses issues related to the preparation of these reactive polymers by direct polymerization of appropriately functionalized monomers as well as the post-polymerization modification of these precursors into functional polymers.

Synthesis of functional polymers by post-polymerization modification.

Recent progress in second-order nonlinear optical polymers and dendrimers

With a span as long as the history of polymer science itself, post-polymerization modification represents a versatile platform for the preparation of diversely functionalized polymers from a single precursor. Starting with the initial efforts by Staudinger in the 1920s, many of the early developments in modern polymer science can be attributed to the utilization of post-polymerization modification reactions. The scope of post-polymerization modification has greatly expanded since the 1990s due to the development of functional group tolerant controlled/living polymerization techniques combined with the (re)discovery of highly efficient coupling chemistries that allow quantitative, chemoselective, and orthogonal functionalization of reactive polymer precursors. After some basic mechanistic considerations, this Highlight will provide an overview of the development and evolution of eight main classes of post-polymerization modification reactions. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

Standing on the shoulders of Hermann Staudinger: Post-polymerization modification from past to present

Aggregation of polar merocyanine dyes has been identified as an important problem in the fabrication of organic materials for photonic applications. In this work, a series of merocyanine dyes is synthesized, and their aggregation is investigated by a combination of several experimental techniques to reveal structure−property relationships. These studies provide clear evidence for the formation of centrosymmetric dimers for all investigated merocyanines in concentrated solution and in the solid state. The thermodynamics of dimerization in liquid solution is studied by concentration-dependent permittivity measurements, UV−vis spectroscopy, and electrooptical absorption experiments. A centrosymmetric dimer structure with antiparallel ordering of the dipole moments is observed in solution by 2D NMR spectroscopy as well as in the solid state by X-ray crystallography and interpreted in terms of dipolar and π−π interactions. The optical properties of the dimer aggregates are satisfactorily explained by an excito...

Dimerization of Merocyanine Dyes. Structural and Energetic Characterization of Dipolar Dye Aggregates and Implications for Nonlinear Optical Materials

A facile high-yield synthetic route has been established for the synthesis of α-hydroxy methyl ketones. These intermediates are important precursors to the tricyanovinyldihydrofuran type of acceptor used in high μβ nonlinear optical chromophores. 3-Hydroxy-3-methyl-2-butanone is one of only three commercially available precursors of this type, limiting the chemist from making systematic studies of structure property relationships. This very general synthetic method allows a wide variety of α-hydroxy ketone structures to be easily made.

α-Hydroxy Ketone Precursors Leading to a Novel Class of Electro-optic Acceptors

A new reactive copolymer system with high, but still variable glass-transition temperatures was synthesized. This was accomplished by copolymerizing various N-substituted maleimides with methylviny...

Reactions on Vinyl Isocyanate/Maleimide Copolymers: NLO-functionalized Polymers with High Glass Transitions for Nonlinear Optical Applications

First hyperpolarizability measurements via hyper-Rayleigh scattering at 1500 nm

We have designed a novel type of NLO-phores based on donor/acceptor (D/A)-substituted peri-arylated naphthalenes 2 with improved efficiency-transparency trade off. In contrast to the conventional one-dimensional conjugated (iD-CT) systems 1 our concept prevents a direct conjugation between the D/A-substituents instead it is based on multidimensional polarizations (e.g. 3D-CT) utilizing through-space interactions. The comparison of iD-CT systems with isomeric compounds of the nonconjugated 3D-CT type reveals much better f3-
values for the latter ones. This could be attributed to more than one electronic transitions in the long wavelength region. As a result these chromophores are not limited by the two-level model.

Periarylated acenes: from one-dimensional to novel multidimensional NLO phores

Phase-matched second-harmonic generation due to anomalous dispersion: tailoring of the refractive indices in three-component systems

The tricyanoquinodimethane group is one of the strongest (pi) -acceptors known to date. Yet it has not been employed as an acceptor in NLO chromophores with common aromatic (pi) -bridges. As an easily accessible example 7-(4-di-n- butylaminophenyl)-7,8,8-tricyanoquinodimethane is examined with respect to thermal/chemical stability and nonlinear optical efficiency. A derivative bearing an hydroxyethyl- spacer was synthesized and covalently attached to functionalized polyimides in a polymer analogous reaction. The second harmonic generation coefficients (d 33 ) of the resulting nonlinear optical polymers were measured using the Maker-fringes experiment.

Roland Dietrich

Papers

Reactions on Vinyl Isocyanate/Maleimide Copolymers: NLO-functionalized Polymers with High Glass Transitions for Nonlinear Optical Applications

First hyperpolarizability measurements via hyper-Rayleigh scattering at 1500 nm

Periarylated acenes: from one-dimensional to novel multidimensional NLO phores

Phase-matched second-harmonic generation due to anomalous dispersion: tailoring of the refractive indices in three-component systems

Tricyanoquinodimethane-derived chromophores for second-order nonlinear optical polymers