objective: bulk-fill composites are a group of composite resins designed for easy and fast filling of large cavities. this study aimed to assess the color stability of bulk-fill composites subjected to xenon radiation and evaluate their color change (&deltae;) following polymerization. methods: in this in vitro experimental study, 30 specimens (4mm in height and 8mm in diameter) were fabricated...

This review article describes developments in chiral metallocenes as polymerization catalysts focusing on C2 symmetric ansa-zirconocene complexes. Selective synthesis of rac-isomers of ansa-zirconocenes are surveyed. Isospecific polymerizations of propylene catalyzed by chiral zirconocenes are summarized. Advanced series of polymerizations by chiral metallocenes such as asymmetric polymerizatio...

An ethoxy-bridged dinuclear indium catalyst was used for the ring opening polymerization of the cyclic ester β-butyrolactone to form the biodegradable polyester poly(hydroxybutyrate) (PHB). The catalyst shows remarkable activity and control during polymerization, allowing for formation of diblock polymers. Addition of high ratios of alcohols to the catalyst leads to fast chain transfer and immo...

The concept of anionic polymerization was first developed by Ziegler and Schlenk in early 1910. Their pioneering work on the polymerization of diene initiated with sodium metal set the stage for the use of alkali metal containing aromatic hydrocarbon complexes as initiators for various α-olefins. In 1939, Scott and coworkers used for the first time the alkali metal complexes of aromatic hydroca...

we develop and study a mathematical model which describes how an inert species contained in the initial monomer/initiator mixture is redistributed by a propagating polymerization front. This study is relevant to the production of polymers for optical applications. @ 2002 Elsevier Science Ltd. All rights reserved. Keywords--Free radical polymerization, Frontal polymerization, Mathematical modeli...

Lewis pair polymerization is a powerful method for preparing soluble polymers bearing pendant active vinyl groups by directly polymerizing dissymmetric divinyl polar monomers. Herein, we present a strategy for synthesizing block and brush copolymers via tandem Lewis pair polymerization of methacrylates, "thiol-ene" click reaction and organocatalytic ring-opening polymerization of lactide.

The monodisperse and controlled polymer nanoparticles have attracted much attention in academic and industrial fields. Due to small size and extremely large specific surface area, nanoparticles could be used to the fields of drug delivery system, microencapsulation, chromate graphy, catalyst, organic/inorganic hybrid materials, and templates for porous inorganic materials. The dispersion polyme...