Photoactive silica nanoparticles: Influence of surface functionalization on migration and kinetics of radical-induced photopolymerization reactions

Construction of Photoinitiator Functionalized Spherical Nanoparticles Enabling Favorable Photoinitiating Activity and Migration Resistance for 3D Printing

A straight-forward method was exploited to construct a multifunctional hybrid photoinitiator by supporting 2-hydroxy-2-methylpropiophenone (HMPP) onto a nano-silica surface through a chemical reaction between silica and HMPP by using (3-isocyanatopropyl)-triethoxysilane (IPTS) as a bridge, and this was noted as silica-s-HMPP. The novel hybrid-photoinitiator can not only initiate the photopolymerization but also prominently improve the dispersion of nanoparticles in the polyurethane acrylate matrix and enhance the filler-elastomer interfacial interaction, which results in excellent mechanical properties of UV-cured nanocomposites. Furthermore, the amount of extractable residual photoinitiators in the UV-cured system of silica-s-HPMM shows a significant decrease compared with the original HPMM system. Since endowing the silica nanoparticle with photo-initiated performance and fairly lower mobility, it may lead to a reduction in environmental contamination compared to traditional photoinitators. In addition, the hybrid-photoinitiator gives rise to an accurate resolution object with a complex construction and favorable surface morphology, indicating that multifunctional nanosilica particles can be applied in stereolithographic 3D printing.

Visible-Light-Sensitive Triazine-Coated Silica Nanoparticles: A Dual Role Approach to Polymer Nanocomposite Materials with Enhanced Properties

Nanocomposite materials are of great interest because of their superior properties. Besides the traditional synthesis methods that require high temperatures or toxic solvents, photopolymerization technology provides a simple, low-cost, and environmentally friendly route in preparing nanocomposites. In this research, the preparation of blue-light-sensitive triazine derivative-coated silica nanoparticles is presented. The resulting triazine-coated silica nanoparticles can play a dual role, i.e., acting as both photoinitiators to trigger photopolymerization reactions under the irradiation of LED@410 nm and fillers to endow the produced photopolymer nanocomposite materials with enhanced properties. Specifically, the triazine-coated silica nanoparticles can successfully induce free radical polymerization of trimethylolpropane triacrylate efficiently under the irradiation of LED@410 nm and demonstrate comparable photoinitiation ability to the triazine derivative-based photoinitiator. The effects of different loading amounts of triazine-coated silica nanoparticles toward the photopolymerization kinetics are also evaluated. By coating with the triazine derivative, the nanoparticles show good dispersion in the polymer matrix and significantly reduce the shrinkage of the samples during the photopolymerization. Moreover, the photocured nanocomposites exhibit enhanced migration stability and mechanical properties when an optimal amount of triazine-coated silica nanoparticles is added in the formulation.

Hybrid silica micro-particles with light-responsive surface properties and Janus-like character

The present work highlights the synthesis and post-modification of silica-based micro-particles containing photo-responsive polymer brushes with photolabile o-nitrobenzyl ester (o-NBE) chromophores.

Polyethylene Nanocomposites for Power Cable Insulations

This review represents a comprehensive study of nanocomposites for power cables insulations based on thermoplastic polymers such as polyethylene congeners like LDPE, HDPE and XLPE, which is complemented by original results. Particular focus lies on the structure-property relationships of nanocomposites and the materials' design with the corresponding electrical properties. The critical factors, which contribute to the degradation or improvement of the electrical performance of such cable insulations, are discussed in detail; in particular, properties such as electrical conductivity, relative permittivity, dielectric losses, partial discharges, space charge, electrical and water tree resistance behavior and electric breakdown of such nanocomposites based on thermoplastic polymers are described and referred to the composites' structures. This review is motivated by the fact that the development of polymer nanocomposites for power cables insulation is based on understanding more closely the aging mechanisms and the behavior of nanocomposites under operating stresses.