Synthesis and characterization of 4-vinylpyridine-functionalized natural rubber as pH-responsive materials

Name: Chanon Sansuk

keyword: Natural rubber

LCSH: Polymers

; 4-(vinylpyridine)

LCSH: Rubber

; Crosslinking

; Grafting

; pH-responsive materials

Abstract: Natural rubber (NR) is a renewable elastomer with excellent mechanical properties. Modification of NR via many chemical-based methods has been widely received much attention as it can improve the physical and chemical properties of NR and extend its application. This thesis research has demonstrated a method for introducing a pH-responsive function to NR using 4-vinylpyridine (4VP). Functionalization of 4VP onto NR via two methods: crosslinking and graft copolymerization, was described. The effects of varying the monomer/polymer concentration, initiator concentration, emulsifier concentration, reaction time, and reaction temperature on the reaction efficiency were investigated. It was found that the gel content of the crosslinking reaction reached 90% when using a P4VP concentration of 150 phr and a BPO concentration of 10 phr for 24 h at 90 oC. The grafting ratio of the grafting reaction achieved 31% when using a 4VP concentration of 100 phr, KPS concentration of 8 phr, and SDS concentration of 10 phr for 3 h at 90 oC. The 4VP-functionalized NRs were characterized using Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy techniques. The thermal properties of the resultant products were determined using thermogravimetric analyzer and differential scanning calorimeter. The pH-responsiveness of the obtained materials was studied using the water swelling experiments and water contact angle measurement. The results showed that unlike the unmodified rubber, the 4VP-functionalized NRs were pH responsive in an acidic condition at pH below 4. Subsequently, the adsorption isotherm and the controlled-release behavior were studied to gain the mechanistic insights and explore the potentials for drug release applications. It was found that the dye adsorption on modified NR showed the Langmuir adsorption isotherm, suggesting a monolayer coverage of the dye. Moreover, the indigo carmine and carbon dot could also be released upon decreasing the pH of solution below 4. In summary, this research led to produce a new responsive rubber-based materials that can be used in biomedical and sensing applications

Thammasat University. Thammasat University Library

Address: BANGKOK

Email: preserv@tu.ac.th

Name: Peerasak Paoprasert

Role: advisor

Created: 2016

Modified: 2021-05-25

Issued: 2021-05-25

DOI: 10.14457/TU.the.2016.586

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Chemistry

Grantor: Thammasat University

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