Preparation Of Polymeric Nanocapsules By Grafting Hyperbranched Polymers On Silica Nanoparticles

In recent years, significant progress has been made in the design and fabrication of hollow polymeric microspheres and nanospheres due to its wide variety of applications such as delivery vesicles for drugs, dyes, or inks; micro-containers for artificial cells, protection shield for proteins, enzymes, or DNA; probing single-cell signaling, catalysis, and so forth. Large numbers of physical and chemical strategies have been developed for the design and fabrication hollow polymeric microspheres and nanospheres. Compared with other methods such as micelle formation of block copolymer, emulsion polymerization and interfacial polymerization, the template methods show the most efficiency in the precise controlling of inner diameters of the micro-and nanocapsules.In this paper, hyperbranched polymers modified silica nanoparticles have been prepared by polycondensation or condensation on the surface of silica nanopartiecles. And the crosslinked degradable polymeric nanocapsules were fabricated from silica templates grafted hyperbranched polymer.1. Preparation of degradable polymeric nanocapsules from hyper-branched poly (amine-ester) grafted nano-silica templates by polycondensationHyperbranched polymers modified silica nanoparticles have been prepared by polycondensation on the surface of silica nanoparticles. The silica templates with hydroxyl-terminated hyperbranched polymers were cross-linked with hexamethylene diisocyanate (HDI), the silica templates were then removed by HF etching to produce the degradable polymeric nanocapsules.2. Preparation of photo-sensitive and degradable polymeric nanocapsules from hyper-branched poly (amine ester) grafted nano-silica templates by polycondensationEarlier, we prepared the degradable and polymeric nanocapsules containing a lot of functional groups based on the widely used sacrificial silica nanoparticles with hydroxyl-terminated hyperbranched polymers, which were cross-linked with hexamethylene diisocyanate (HDI) by polycondensation. In this section, the silica templates with hydroxyl-terminated hyperbranched polymers were cross-linked with 4, 4'-Azobenzene dibenzoyl chloride (ADC), therefore the polymer nanocapsules had photochromism.3. Preparation of photo-sensitive and degradable polymeric nanocapsules from hyper-branched polymers grafted nano-silica templates by condensationIn this section, we prepared the photo-sensitive and degradable polymeric nanocapsules containing a lot of functional groups based on the widely used sacrificial silica nanoparticles by condensation. Hydroxyl-terminated hyperbranched polymers were obtained by condensation reaction and cross-linked with 4, 4'-Azobenzene dibenzoyl chloride (ADC). Then, the photo-sensitive and degradable polymeric nanocapsules were got by the silica templates removed by HF etching.4, 4'-Azobenzene dibenzoyl chloride (ADC) is both monomer and cross-linker in this experiment.