https://cyberleninka.org/article/n/1018032.pdf

Polymer nanotechnology: Nanocomposites

In the 21st century, soft materials will become more important as functional materials because of their dynamic nature. Although soft materials are not as highly durable as hard materials, such as metals, ceramics, and engineering plastics, they can respond well to stimuli and the environment. The introduction of order into soft materials induces new dynamic functions. Liquid crystals are ordered soft materials consisting of self-organized molecules and can potentially be used as new functional materials for electron, ion, or molecular transporting, sensory, catalytic, optical, and bio-active materials. For this functionalization, unconventional materials design is required. Herein, we describe new approaches to the functionalization of liquid crystals and show how the design of liquid crystals formed by supramolecular assembly and nano-segregation leads to the formation of a variety of new self-organized functional materials.

Functional liquid-crystalline assemblies: self-organized soft materials.

“Life is branched” was the motto of a special issue of Macromolecular Chemistry and Physics1 on “Branched Polymers”, indicating that branching is of similar importance in the world of synthetic macromolecules as it is in nature. The significance of branched macromolecules has evolved over the last 30 years from just being considered as a side reaction in polymerization or as a precursor step in the formation of networks. Important to this change in perception of branching was the concept of “polymer architectures”, which formed on new starand graft-branched structures in the 1980s and then in the early 1990s on dendrimers and dendritic polymers. Today, clearly, controlled branching is considered to be a major aspect in the design of macromolecules and functional material. Hyperbranched (hb) polymers are a special type of dendritic polymers and have as a common feature a very high branching density with the potential of branching in each repeating unit. They are usually prepared in a one-pot synthesis, which limits the control on molar mass and branching accuracy and leads to “heterogeneous” products with a distribution in molar mass and branching. This distinguishes hyperbranched polymers from perfectly branched and monodisperse dendrimers. In the last 20 years, both classes of dendritic polymers, dendrimers as well as hb polymers, have attracted major attention because of their interesting properties resulting from the branched architecture as well as the high number of functional groups.2 The challenging synthesis of the dendrimers attracted especially scientists with a strong organic chemistry background and led to beautifully designed macromolecules, which allowed a deeper insight into the effect of branching and functionality. Dendrimers have been considered as perfect “nano-objects” where one can control perfectly size and functionality, which is of high interest in nanotechnology and biomedicine. hb polymers, however, were considered from the beginning as products suitable for larger-scale application in typical polymer fields like coatings and resins, where a perfect structure is sacrificed for an easy and affordable synthetic route. Thus, the first structures that were reported paralleled the chemistry used for linear polymers like typical polycondensation for polyester synthesis. More recently, unconventional synthetic methods have been adopted also for hb polymers and related structures. Presently, a vast variety of highly branched structures have been realized and studied regarding their properties and potential application fields. Excellent reviews appeared covering synthesis strategies, properties, and applications, like the very recent tutorial by Carlmark et al.,3 the comprehensive book on hyperbranched polymers covering extensively synthesis and application * E-mail: voit@ipfdd.de; lederer@ipfdd.de. Chem. Rev. 2009, 109, 5924–5973 5924

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Hyperbranched and highly branched polymer architectures--synthetic strategies and major characterization aspects.

A review of stimuli-responsive shape memory polymer composites

Recent advances in polyaniline research: Polymerization mechanisms, structural aspects, properties and applications

Aliphatic hyperbranched polyesters based on 2,2-bis(methylol)propionic acid—Determination of structure, solution and bulk properties

A fourth generation hyperbranched polyester polyol based on bis-MPA and a PP50 core molecule (Boltorn H40) as well as its fractions obtained by preparative SEC were characterized with respect to composition, molar mass, and structure using NMR, SEC−MALS, ESI−MS, and DSC techniques. The content of dendritic units and the degree of branching (DB) are significantly lower than expected for a random polymerization, thus indicating that the hydroxyl groups in the linear repeat units are less reactive than those in terminal repeat units. The main side reaction in the synthesis of Boltorn H40 is deactivation of the bis-MPA carboxyl groups leading to structures without a core molecule. This side reaction influences mainly Mn, and to a lesser degree the Mw value of Boltorn H40. Furthermore, some of the hydroxyl groups react to ether groups. Etherification as a side reaction is of minor importance since the content of ether groups is below 1%. The obtained results indicate that despite deactivation of carboxyl gro...

Characterization of a Commercial Hyperbranched Aliphatic Polyester Based on 2,2-Bis(methylol)propionic Acid

The polyol method was employed for the first time to synthesize cuprous oxide nanowires using only a precursor of Cu(II) acetate monohydrate and diethylene glycol (DEG). With careful control of the reaction temperature (190 °C), the precursor concentration (0.01−0.1 mol/L), and the reaction time (6 h), we prepared Cu2O nanowires with a diameter of approximately 20 nm and a length up to 5 μm. The nanowires were characterized by SEM, TEM, XRD, and IR spectroscopy.

Majda Žigon

Papers

Aliphatic hyperbranched polyesters based on 2,2-bis(methylol)propionic acid—Determination of structure, solution and bulk properties

Characterization of a Commercial Hyperbranched Aliphatic Polyester Based on 2,2-Bis(methylol)propionic Acid

Cuprous Oxide Nanowires Prepared by an Additive-Free Polyol Process

Characterization of commercial aliphatic hyperbranched polyesters

Comparison of the properties of clay polymer nanocomposites prepared by montmorillonite modified by silane and by quaternary ammonium salts