Crystalline and disordered state of poly(dihexylsilylene) copolymers

A systematic comparison of random copolymers, derived from poly(dihexylsilylene) (PDHS) by incorporation of monomeric units with shorter unbranched alkyl side chains, has been carried out based on calorimetry, variable temperature UV spectroscopy, and 29Si MAS (magic angle spinning) solid state NMR investigations. Also, hexylmethylsilylene units and branched monomers have been copolymerized. Up to 10% comonomer with shorter linear side chains (i. e., pentyl to propyl) could be incorporated into PDHS without impeding the all-trans order of the crystalline phase. In this case, the UV absorption maximum of the crystalline low-temperature phase was affected only slightly according to the length and fraction of the comonomer side chains. A less ordered crystal structure (λmax = 345-355 nm) was observed when the content of comonomers with shorter side chains was about 20%. Yet, all these materials form conformationally disordered mesophases. A clear disordering transition and corresponding thermochromism was not observed any more when 50% of propyl side chains were incorporated. The order of the crystalline and the mesophase is also strongly perturbed if only a small fraction (4%) of the side chains are branched at C2

Order and thermochromism of poly(di-n-alkyl)silane copolymers

A series of poly(di-n-alkyl)silane copolymers derived from Poly(di-n-hexyl)silane, PDHS, was prepared. Mesomorphic phase transitions of these copolymers depend on fraction as well as on the size of the comonomers. DSC and temperature dependent UV-spectroscopy were employed to study the effect of constitutional disorder on the length of all-trans σ-conjugated Si---Si catenated chromophores

Atom transfer radical polymerization in inverse miniemulsion: A versatile route toward preparation and functionalization of microgels/nanogels for targeted drug delivery applications

AbstractThis short review describes application of atom transfer radical polymerization (ATRP) in inverse miniemulsion and disulfide–thiol exchange to prepare well-defined biodegradable functional nanogels (ATRP-nanogels). Due to the formation of uniform network, the ATRP-nanogels have higher swelling ratios, better colloidal stability, and controlled degradation, as compared to nanogels prepared by conventional free-radical polymerization. Various water-soluble biomolecules such as anticancer drugs, carbohydrates, proteins, and star branched polymers were incorporated into ATRP-nanogels at high loading level, by in-situ physical loading or by in-situ chemical incorporation via covalent bonds. The nanogels crosslinked with disulfide or polyester linkages were degraded either in the presence of biocompatible reducing agents or by hydrolysis for controllable release of the encapsulated drugs. ATRP-nanogels contain bromine end groups that enable further chain extension and functionalization with biorelated molecules. They are also easily functionalized by copolymerization with functional monomers or use of functional ATRP initiator during synthesis. These functional nanogels have capability to be further chemically modified and bioconjugated with cell-targeting proteins, antibodies, and integrin-binding peptides to increase cellular uptake via clathrin-mediated endocytosis. These results suggest that such well-defined functional nanogels have great potential for targeted drug delivery applications

Создание новых композиционных материалов на полимерной основе для применения в аддитивных технологиях

В настоящей работе приведено исследование композиционных филаментов "ABS - углеволокно" с содержанием углеволокна до 10 вес.%. Исследована макроструктура полученных филаментов, в частности наибольшее внимание уделено исследованию ориентирования волокон в объеме филамента. Описаны технологические особенности процесса получения композиционного филамента, приведена наиболее оптимальная схема получения филамента, в том числе описана оптимальная технология подготовки углеволокна для введения в композит.In the present work, a study of composite filaments "ABS-carbon fiber" with a carbon fiber content of up to 10% by weight is made. The macrostructure of the filaments is studied, in particular, the greatest attention is paid to the study of fiber orientation in the filament volume. Technological features of the process of composite filament preparation are described, the most optimal scheme of filament production is given, besides the optimal technology of carbon fiber preparation for introduction into the composite is described

ATRP in the design of functional materials for biomedical applications

Atom Transfer Radical Polymerization (ATRP) is an effective technique for the design and preparation of multifunctional, nanostructured materials for a variety of applications in biology and medicine. ATRP enables precise control over macromolecular structure, order, and functionality, which are important considerations for emerging biomedicaldesigns. This article reviews recent advances in the preparation of polymer-based nanomaterials using ATRP, including polymer bioconjugates, block copolymer-based drug delivery systems, cross-linked microgels/nanogels, diagnostic and imaging platforms, tissue engineering hydrogels, and degradable polymers. It is envisioned that precise engineering at the molecular level will translate to tailored macroscopic physical properties, thus enabling control of the key elements for realized biomedicalapplications