Electronic Theses and Dissertation

ABSTRAK

Khalisna Azkia. (2026). Karakterisasi Sifat Termomekanik, Optik Dan Fotostabilitas Nanohidrogel Berbasis Polyvinyl Alcohol Carbon Quantum Dots Dari Limbah Kopi Robusta. [Skripsi. Universitas Syiah Kuala]. Dibawah Bimbingan Dr. Muhammad Nazar, S.Pd., M.SCST., dan Dra. Erlidawati, M.Si.

Nanohidrogel berbasis polyvinyl alcohol (PVA) berpotensi sebagai material fungsional. Penambahan carbon quantum dots (CQDs) dari limbah kopi robusta diharapkan memengaruhi sifat termomekanik, optik, fotostabilitas, dan penyerapan air. Penelitian ini bertujuan mengkarakterisasi sifat termomekanik, optik, fotostabilitas, dan penyerapan air film nanohidrogel PVA–CQDs dengan variasi konsentrasi CQDs (F0, F1, F2, dan F3). Karakterisasi meliputi thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), tensile strength (TS), elongation at break (EB), uji ketahanan panas, swelling dalam berbagai pH, water uptake, analisis warna CIELAB, dan uji fotostabilitas. Hasil menunjukkan seluruh formulasi mengalami satu tahap degradasi termal, sedangkan penambahan CQDs memengaruhi karakteristik termal secara tidak linier. Formulasi F2 menghasilkan TS tertinggi sebesar 22,16 MPa, sedangkan EB tertinggi diperoleh pada F1 sebesar 86,70%. Seluruh sampel menunjukkan kehilangan massa yang rendah setelah pemanasan pada 100°C selama 1 jam. Swelling meningkat hingga mencapai kondisi relatif konstan, dengan nilai tertinggi 16,828 pada F2 dalam larutan pH 11. Water uptake tertinggi diperoleh pada F0 sebesar 1861,98%, sedangkan F2 mengalami kehilangan massa selama perendaman. Nilai L* seluruh film relatif tinggi dan ΔE meningkat seiring peningkatan konsentrasi CQDs. Setelah penyinaran UV, seluruh film tetap utuh dengan perubahan RGB kurang dari 10% dan intensitas fluoresensi (IF) yang tidak linier. Variasi konsentrasi CQDs memengaruhi sifat termal, mekanik, optik, fotostabilitas, dan penyerapan air film nanohidrogel berbasis PVA.
Kata Kunci: carbon quantum dots, limbah kopi robusta, nanohidrogel PVA, sifat termomekanik, fotostabilitas, sifat optik.

Khalisna Azkia. (2026). Karakterisasi Sifat Termomekanik, Optik Dan Fotostabilitas Nanohidrogel Berbasis Polyvinyl Alcohol Carbon Quantum Dots Dari Limbah Kopi Robusta. [Skripsi. Universitas Syiah Kuala]. Dibawah Bimbingan Dr. Muhammad Nazar, S.Pd., M.SCST., dan Dra. Erlidawati, M.Si. Polyvinyl alcohol (PVA)-based nanohydrogels have considerable potential as functional materials. The incorporation of carbon quantum dots (CQDs) derived from robusta coffee waste is expected to influence their thermomechanical, optical, photostability, and water absorption properties. This study aimed to characterize the thermomechanical, optical, photostability, and water absorption properties of PVA–CQD nanohydrogel films with different CQD concentrations (F0, F1, F2, and F3). The characterization included thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), tensile strength (TS), elongation at break (EB), heat resistance testing, swelling behavior at different pH values, water uptake, CIELAB color analysis, and photostability testing. The results showed that all formulations underwent a single-stage thermal degradation, while the addition of CQDs affected the thermal characteristics in a non-linear manner. Formulation F2 exhibited the highest tensile strength of 22.16 MPa, whereas the highest elongation at break was obtained for F1 at 86.70%. All samples showed low mass loss after heating at 100°C for 1 h. The swelling ratio increased until reaching a relatively constant state, with the highest value of 16.828 observed for F2 in a pH 11 solution. The highest water uptake was achieved by F0 at 1861.98%, whereas F2 exhibited mass loss during immersion. All films exhibited relatively high L* values, while ΔE increased with increasing CQD concentration. After UV irradiation, all films maintained their structural integrity, with RGB changes of less than 10% and non-linear variations in fluorescence intensity. Overall, the variation in CQD concentration influenced the thermal, mechanical, optical, photostability, and water absorption properties of PVA-based nanohydrogel films. Keywords: carbon quantum dots, robusta coffee waste, ss nanohydrogel, thermomechanical properties, photostability, optical properties.