The design of an imidazole-based salt by enzyme-mimicking allowed controlling the ring-opening polymerization of L- and D-LA monomers in bulk. Kinetic study supports a bifunctional activation process only slightly different from the one occurring in Nature.

statement of problem: for many years, application of the composite restoration with a thickness less than 2 mm for achieving the minimum polymerization contraction and stress has been accepted as a principle. but through the recent development in dental material a group of resin based composites (rbcs) called bulk fill is introduced whose producers claim the possibility of achieving a good rest...

Various types of controlled/living radical polymerizations, or using the IUPAC recommended term, reversible-deactivation radical polymerization (RDRP), conducted inside nano-sized reaction loci are considered in a unified manner, based on the polymerization rate expression, Rp = kp[M]K[Interm]/[Trap]. Unique miniemulsion polymerization kinetics of RDRP are elucidated on the basis of the followi...

Hydrophobic polymer amide (HPA) could have been one of the first normal density materials to accrete in space. We present ab initio calculations of the energetics of amino acid polymerization via gas phase collisions. The initial hydrogen-bonded di-peptide is sufficiently stable to proceed in many cases via a transition state into a di-peptide with an associated bound water molecule of condensa...

Ziegler-Natta polymerization catalysts were characterized by a complex of surface- and bulk-sensitive methods (DRIFTS, XPS, ESR, and XAS = XANES + EXAFS). A diffuse-reflectance Fourier-transform IR spectroscopy (DRIFTS) study showed the presence of strong Lewis acid sites in different concentrations and absence of strong basic sites in the polymerization catalysts. X-ray photoelectron spectrosc...

The reverse atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was successfully carried out in 1-butyl-3-methylimidazolium hexafluorophosphate with 2,2 -azobisisobutyronitrile/CuCl2/bipyridine as the initiating system, which had been reported as not able to promote a controlled process of MMA in bulk. The living nature of the polymerization was confirmed by kinetic studies...

In this study, in-situ bulk polymerization was investigated for obtaining flame retardant polystyrene (PS). The halogenated and phosphoric compounds were used as flame retardant additives and Perkadox 30 was used as a synergist. The flammability of the PS was evaluated by thermogravimetric analyzer (TGA), limiting oxygen index (LOI) and UL-94 tests. The results show that polymerization process ...

Paclitaxel, a polyol chemotherapeutic agent, was covalently conjugated through its 2'-OH to polylactide with 100% regioselectivity via controlled polymerization of lactide mediated by paclitaxel/(BDI-II)ZnN(TMS)(2) (BDI-II = 2-((2,6-diisopropylphenyl)amino)-4-((2,6-diisopropylphenyl)imino)-2-pentene). The steric bulk of the substituents on the N-aryl groups of the BDI ligand drastically affecte...

Pd complexes with diimine ligands promoted the controlled cyclopolymerization of 1,6-dienes and 1,6,11-trienes to afford polymers containing 1,2-trans-cyclopentane groups with well-regulated stereochemistry. The polymerization proceeded with quantitative cyclization of the monomer, even under bulk conditions or in copolymerization reactions with ethylene and aolefins. The polymerization of mono...

The objective of this study was to investigate changes in polymerization stress and elastic modulus for light-cured bulk-fill resin composites following irradiation. Crack analysis was applied to obtain the stresses for 24 h after irradiation, which were calculated from the lengths of cracks in a glass mold bonded to the composites. The elastic modulus was repeatedly measured by nano-indentatio...