Tuning the surface microstructure and gradient properties of polymers with photopolymerizable polysiloxane-modified nanogels

Abstract

This paper reports a series of photopolymerizable polysiloxane-modified nanogels for regulating surface microstructure and gradient property of polymers, which were synthesized by solution polymerization under different feed ratios of a methacrylate-modified polysiloxane, urethane dimethacrylate (UDMA) and isobornyl methacrylate (IBMA) in the presence of a thiol chain transfer agent. The nanogel structure and composition were characterized by proton nuclear magnetic resonance (1H-NMR), Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscope (TEM), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The dispersion of these nanogels in triethylene glycol dimethacrylate (TEGDMA) can reduce the onset and magnitude of shrinkage stress during polymerization without compromise to mechanical properties of the resulting polymers. Most importantly, as demonstrated by elemental analysis and X-ray photoelectron spectroscopy (XPS), the nanogels exhibit good self-floating ability in the monomer/polymer matrix and the increase of polysiloxane content in the nanogel can enhance the self-floating capability due to the lower surface tension and energy associated with the polysiloxane component. As a result, the polysiloxane-modified nanogels can spontaneously form a concentration gradient that can be locked in upon photopolymerization leading to a well-controlled heterogeneous polymer that presents a gradient change in thermal stability. With the increase of polysiloxane content, the thermal stability of the polymer was improved significantly. Furthermore, the enrichment of the nanogel on the surface resulting from the good self-floating ability can reduce the dispersion surface energy of gradient polymer film and generate a more hydrophobic surface with altered surface microstructure. These photopolymerizable polysiloxane-modified nanogels are demonstrated to have potential broad application in the preparation of gradient polymer with controlled surface properties.

Ions-modified nanoparticles affect functional remineralization and energy dissipation through the resin-dentin interface

“…On the whole, the hydroxyapatite with poor crystallinity has improved bioactivity, biocompatibility and biodegradability as compared with the stoichiometric hydroxyapatite. The dissolution of hydroxyapatite increases the level of supersaturation, and thus raises the velocities of nucleation and growth of dentin-like apatite nanocrystals (Chen et al, 2014).…”

Controlled nanogel and macrogel structures from self-assembly of a stimuli-responsive amphiphilic block copolymer

“…Chain-growth reactions have also been applied to form polymers with multi-chain structures. Random structured, highly branched polymers were synthesized through solution polymerization of a dimethacrylate and monomethacrylate with a chain transfer agent 4–6 . Primary chain length and branching density of these polymers can be tuned by varying the concentration of the dimethacrylate crosslinker and chain transfer agent.…”

Gradient polymer networks formed by photopolymerization with self‐floating polysiloxane‐containing nanogel

“…However, this method is hugely restricted in preparing gradient polymers with high performances that are related to the structure, composition and molecular weight of the polymer, because the properties of the prepared gradient polymer using the polysiloxane benzophenone photoinitiator only can be regulated by the polymer molecular weight, which relates to the photoinitiator closely. In view of this, we propose a new idea that the polysiloxane is introduced into nanogels to obtain polysiloxane‐containing nanogels for preparing gradient polymers . The polysiloxane‐containing nanogels will have both self‐floating feature of polysiloxanes and easy adjustment feature of structures of nanogels, thereby easily regulating structures and properties of gradient polymers.…”