Sains Malaysiana 44(6)(2015): 779–785

pH Sensitive Hydrogel Based on Poly(Acrylic Acid) and Cellulose Nanocrystals

(Hidrogel Sensitif terhadap pH Berasaskan Poli(Asid Akrilik) Diperkuatkan Selulosa Nanohablur)

LIM SZE LIM, ISHAK AHMAD* & AZWAN MAT LAZIM

Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi,

Selangor Darul Ehsan, Malaysia

Received: 15 January 2014/Accepted: 15 November 2014

ABSTRACT

The purpose of this study was to produce a novel pH sensitive hydrogel with superior thermal stability, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) in CNC suspension. The mixture was casted onto petri dish to obtain disc shape hydrogel. PAA/cellulose hydrogel with the same composition ratio were also prepared as control. The effect of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH was studied. The obtained hydrogel was further subjected to different tests such as thermogravimetric analysis (TGA) to study the thermal behavior, Fourier transform infrared for functional group identification and swelling test for swelling behavior at different pH. The cross-linking of PAA was verified with FTIR with the absence of C=C double bond. In TGA test, PAA/CNC hydrogel showed significantly higher thermal stability compared with pure PAA hydrogel. The hydrogel obtained showed excellent pH sensitivity and experienced maximum swelling at pH7. The PAA/CNC hydrogel can be developed further as drug carrier.

Keywords: Acrylic acid; cellulose nanocrystals; hydrogel; swelling behavior

ABSTRAK

Objektif kajian ini adalah untuk menghasilkan hidrogel poli(asid akrilik) (PAA) diperkuatkan selulosa nanohablur (CNC) yang bukan sahaja sensitif terhadap rangsangan pH tetapi juga mempunyai sifat terma yang baik. CNC diekstrak daripada serabut kenaf melalui rawatan alkali dan rawatan pelunturan dan diikuti hidrolisis asid. Asid akrilik (AA) ditautsilangkan dengan menggunakan agen tautsilang (N,N-metilenabisakrilamid) dalam ampaian CNC. Campuran kemudian dituang ke dalam piring petri panas untuk mendapatkan hidrogel yang berbentuk cakera. Hidrogel PAA/selulosa dengan komposisi yang sama juga telah dihasilkan sebagai kawalan. Kesan parameter tindak balas seperti nisbah PAA dan CNC terhadap sifat pembengkakan hidrogel telah dikaji. Hidrogel yang dihasilkan diciri dengan analisis termogravimetri (TGA) untuk mengkaji sifat terma hidrogel yang dihasilkan. Transformasi Fourier inframerah pula digunakan untuk mengenal pasti kumpulan berfungsi hidrogel. Selain itu, ujian pembengkakan juga telah dijalankan untuk mengkaji sifat pembengkakan hidrogel pada pH yang berbeza. Kehilangan puncak C=C membuktikan bahawa asid akrilik telah berjaya ditautsilangkan kepada poli(asid akrilik). Dalam analisis TGA pula, hidrogel PAA/CNC menunjukkan kestabilan terma yang lebih baik berbanding dengan hidrogel PAA. Hidrogel yang dihasilkan adalah sensitif terhadap perubahan pH dan mencapai pembengkakan maksimum pada pH7. Hidrogel PAA/CNC mempunyai potensi untuk dijadikan pembawa ubat secara terkawal.

Kata kunci: Asid akrilik; hidrogel; selulosa nanohablur; sifat pembengkakan

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*Corresponding author; email: gading@ukm.edu.my