Synthesis of PAM/TiO₂ Composite Microspheres with Hierarchical Surface Morphologies

Abstract

PAM/TiO 2 composite microspheres with hierarchical surface structures were synthesized by the reaction between tetrabutyl titanate (TBOT) located within porous polyacrylamide (PAM) microgels and water in a moist atmosphere. The morphology and composition of the composite microspheres were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FI-IR), X-ray diffraction (XRD), N 2 absorption analysis, and mercury porosimetry, respectively. The results indicated that the composite microspheres, with different hierarchical surface morphologies, could be obtained by controlling the cross-linking degree of the porous PAM microgels, the relative humidity of the gas phase, the amount of residual impregnation liquid, and the TBOT concentration in the porous PAM microgels. Although the surface morphologies of the composite microspheres are varied, the morphologies are typically divided into three categories: (1) wrinkled surfaces covered with large dense TiO 2 particles; (2) porous structures sparsely suffused with large TiO 2 particles along the fringes and inner walls of the porous channels; and (3) macroporous surfaces with small TiO 2 particles distributed ubiquitously. The incorporation of TiO 2 particles into PAM microgels resulted in an obvious increase in specific surface area, and the pore size distribution of the microspheres depended strongly on the size of TiO 2 particles. The method described herein provides a potential way for finetuning the morphology and surface property of composite microspheres. Additionally, this method can be used to fabricate various composite materials through altering the precursor and/or polymeric microgel template.

Colloidal liquid aphrons directed growth of sol–gel silica exhibiting bimodal porosities

“…Moreover, uniform mesopores were found in this research under mild base-catalyzed solegel process. The formation of those mesopores in the macroporous walls is attributed to the compact packing of nanoscale silica spheres, which also designed synthesized in our previous work when microgel was used as soft template to develop hierarchical porous materials of the composite microspheres of PAM/TiO 2 , and poly (NIPAM-co-AA)/SiO 2 [10,11].…”

“…For instance, water-insoluble polystyrene (PS) microsphere as a hard macropore template and amphiphilic surfactant as a soft mesostructural template has been used to prepare macroporous/mesoporous silica materials [9]. Microgel as soft template was developed and hierarchical porous materials of the composite microspheres of PAM/ TiO 2 , and poly (NIPAM-co-AA)/SiO 2 were successfully obtained [10,11] in our group. Foams such as commercial polyurethane (PU) were also used as a macrostructure scaffold and trilock copolymer Pluronic P123 as a mesostructure template to prepare hierarchically porous silica materials via economical pathway [3].…”

Microhydrogel surface-supported quaternary ammonium peroxotungstophosphate as reusable catalytic materials for oxidation of DBT

“…PAM microgels were synthesized according to our previous research [20]. A typical process is as follows.…”

“…Employing poly(N-isopropylacrylamide-co-acrylic acid), poly(N-isopropylacrylamide-comethacrylic acid), polyacrylamide, and poly(N-isopropylacrylamide) 1381-5148/$ -see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.reactfunctpolym.2011.01.003 microgels as templates, several interesting polymeric composite microspheres have been successfully synthesized [16][17][18][19][20][21]. After combing our previous research and the protocol for the construction of the integration microsphere with the water pool and surfactant shell used in biphasic catalytic reactions, composite microspheres with PAM microgel cores and shells of polymerizable surfactant/polyoxometalate complexes were synthesized.…”

Silicon dioxide hollow microspheres with porous composite structure: Synthesis and characterization

“…PAM microspheres with porous structures were prepared by the freeze-drying treatment [20]. A typical preparation is as follows: 0.1 g of PAM micro-gel was swollen by adding 8 ml of doubledistilled water and then the sample, after being quenched in liquid nitrogen, was freeze-dried by an ALPHA1-2 freeze-drying instrument at À55°C for 24 h. The PAM micro-gels with porous structures were finally obtained.…”