Construction and Swelling Properties of Thermosensitive N-isopropyl Acrylamide Microspheres With Controllable Size.

Chen Wang,Liang Wang,Yao Hui,Si-Xian Lu,Wei-Jia Chen,Yan-Ru Lu

doi:10.3390/ma12152428

Chen Wang, Liang Wang + Show 4 more

Open Access

https://doi.org/10.3390/ma12152428

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Abstract

In recent years, thermosensitive poly(N-isopropylacrylamide) (PNIPAM) microspheres have received extensive attention due to their many advantages, and their size and swelling ratio are two crucial factors. In this paper, homogeneous and hollow thermosensitive microspheres were prepared by free radical polymerization in an aqueous solution. The effects of the process parameters on the size of the microspheres were studied. The results indicated that the change in size during reaction at different temperatures was not obvious. The size of the microspheres ranged from 802 ± 35.4 nm to 423 ± 33.7 nm with the changes in the dosage of the initiator. Meanwhile, it was observed that the size of microspheres was slightly reduced due to the increase of reaction time. When the dosage of methyl methacrylate (MAA) is increased, the size of the hollow microspheres increased by more than 110%. The average size of the microspheres was smaller when the content of sodium dodecyl sulfate (SDS) was 3 wt%. The microspheres with varying reaction parameters showed a continuous decreasing swelling ratio when the temperatures were changed from 28 °C to 35 °C. In comparison with homogeneous microspheres, the average swelling ratio of hollow microspheres was larger.

Highlights

Thermosensitive poly(N-isopropylacrylamide) (PNIPAM) hydrogel microspheres have intriguing potential applications in switching intelligent systems [1,2], optical, photonic materials [3,4], and biological materials [5,6]
The shrinking and swelling process of the hydrogel microspheres is controlled by diffusion transport, and the response rate is inversely proportional to the square of the smallest dimension of the gel [14]
PNIPAM microspheres have attracted a great deal of interest because of their small size and fast stimuli-responsive behavior, proving that it has got great application potentials [15,16]

Summary

Introduction

Thermosensitive poly(N-isopropylacrylamide) (PNIPAM) hydrogel microspheres have intriguing potential applications in switching intelligent systems [1,2], optical, photonic materials [3,4], and biological materials [5,6]. The reported preparation methods of PNIPAM hollow microspheres included the template method [9], inverse emulsion polymerization [10], in situ interfacial polymerization [11], Shirasu. The shrinking and swelling process of the hydrogel microspheres is controlled by diffusion transport, and the response rate is inversely proportional to the square of the smallest dimension of the gel [14]. PNIPAM microspheres have attracted a great deal of interest because of their small size and fast stimuli-responsive behavior, proving that it has got great application potentials [15,16].

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