Synthesis and characterization of PNIPAM microgel core–silica shell particles

  • Ngoc-Hanh Cao-Luu
  • Quoc-Thai Pham
  • Zong-Han Yao
  • Fu-Ming Wang
  • Chorng-Shyan ChernEmail author
Chemical routes to materials


We developed a simple effective approach to prepare poly(N-isopropylacrylamide-co-acrylamide-co-N,N′-methylenebisacrylamide) (PNIPAM/AM/MBA) microgel core–silica shell particles with narrow particle size distribution via the sol–gel reaction of silica precursor deposited directly on the microgel particle surface in the presence of 3-glycidyloxypropyltrimethoxysilane (GLYMO). MBA was used as the cross-linking agent for the formation of microgel with the cross-linked network structure and GLYMO used as a coupling agent. The morphology of hybrid core–shell particles including the shape, core size, shell thickness and surface roughness was governed by the key components of AM and GLYMO. PNIPAM/AM/MBA microgel core–silica shell particles show desirable spherical shape, distinct core–shell structure and raspberry-like particle morphology. In contrast, PNIPAM/MBA microgel core–silica shell particles formed without resort to AM and GLYMO result in very poor silica encapsulation, thereby leading to undesired particle morphology. Incorporation of AM units into PNIPAM/MBA microgel particles increases the lower critical solution temperature (LCST). Furthermore, encapsulation of PNIPAM/AM/MBA microgel particles by silica does not affect the LCST to an appreciable extent, but it greatly reduces the thermo-sensitivity of the hybrid core–shell particles. Finally, the feasibility of using these PNIPAM-based core–silica shell particles as drug carriers was demonstrated.



This study was supported by Ministry of Science and Technology, Taiwan.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Authors and Affiliations

  1. 1.Department of Chemical EngineeringNational Taiwan University of Science and TechnologyTaipeiTaiwan
  2. 2.Graduate Institute of Applied Science and TechnologyNational Taiwan University of Science and TechnologyTaipeiTaiwan
  3. 3.Department of Internal MedicineNational Taiwan University HospitalTaipeiTaiwan

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