Preparation and characterization of a nanocellulose reinforced light-polymerized methacrylate-based dental adhesive
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Journal Title
Journal ISSN
Volume Title
Kemian tekniikan korkeakoulu |
Master's thesis
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Author
Date
2019-05-07
Department
Major/Subject
Fiber and Polymer Engineering
Mcode
CHEM3024
Degree programme
Master's Programme in Chemical, Biochemical and Materials Engineering
Language
en
Pages
5+83
Series
Abstract
The purpose of this research work was to develop a new dental adhesive, by inclusion of cellulose nanocrystals (CNCs) into a polymer matrix. CNCs were chosen as a component for dental adhesives due to its mechanical properties, dimensions, low density and biocompatibility. Two methacrylate co-monomer mixtures: 2-hydroxyethyl methacrylate (HEMA) and Bisphenol A Glycidyl Methacrylate (bisGMA) were used as model dentin adhesive polymer matrices. In the work, three types of CNCs were prepared by acid hydrolysis, using three acids: sulphuric, phosphoric and hydrochloric acid. In order to improve dispersion of CNCs in methacrylate-based matrices, each type of CNCs was modified. 3-Trimethoxysilyl propyl methacrylate was chosen as a coupling agent able to improve dispersion and co-polymerization of CNCs in methacrylate-based matrices. FTIR and Liquid-State NMR analysis were used to confirm the results of CNCs modification. Based on evaluation of dispersibility of CNCs and the results of modification, CNCs prepared through phosphoric acid hydrolysis (PCNCs) were found as the most suitable component for the dental adhesive application. Nanocomposite samples were prepared from both matrices and freeze-dried pristine and modified PCNCs with the weight concentration up to 5%. Influence of the incorporated pristine and modified PCNCs on the conversion profile of the experimental nanocomposite was studied. Mechanical properties of the in situ light-polymerized nanocomposites were studied by Flexural strength test. TEM was used to investigate nanostructure of the experimental dental adhesives. Real-time FTIR photo-polymerization studies were done to evaluate the effect of PCNCs inclusion on the kinetics of polymerization for the nanocomposites. The results of mechanical testing showed a slight improvement of flexural strength for the nanocomposite out of HEMA-based resin and 5 wt.% PCNCs, however, modified PCNCs did not improve the strength of the experimental material. For the nanocomposite samples out of bisGMA-based resin PCNCs slightly reduced flexural strength. Study of nanostructure revealed the improved dispersibility of modified PCNCs in the matrix compared to pristine PCNCs. Inclusion of pristine or modified PCNCs did not reduce the degree of conversion of the resulting nanocomposites. The outcomes of this work demonstrate that PCNCs have a potential to become a valuable component in methacrylate-based polymer matrices. PCNCs could act as reinforcement part for lacking mechanical strength HEMA-based adhesives, while for the strong hydrophobic bisGMA-based matrix PCNCs could increase biocompatibility. However, the current research provides the information for the further studies, and comprehensive research is required.Description
Supervisor
Kontturi, EeroThesis advisor
Vallittu, PekkaHeise, Katja
Keywords
cellulose nanocrystal, methacrylate-based dental adhesive, CNC, nanocomposite, phosphoric acid hydrolysis, in situ photo-polymerization
