an approach for preparing a bio-hybrid material with special water affinity from poly(vinyl alcohol)

80 Pages·2015·1.97 MB·English

AN APPROACH FOR PREPARING A BIO-HYBRID MATERIAL
WITH SPECIAL WATER AFFINITY FROM
POLY(VINYL ALCOHOL), RICE STARCH
AND SILK FIBROIN FOR WOUND
DRESSING APPLICATION

PUSITA KUCHAIYAPHUM

THE GRADUATE SCHOOL OF SCIENCE AND TECHNOLOGY
NIIGATA UNIVERSITY
MARCH 2015
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ACKNOWLEDGEMENT
The thesis has been accomplished with the collaboration between the Graduate
School of Science and Technology, Niigata University, Niigata, Japan and Department
of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand.
I would like to express my heartfelt gratitude and appreciation to my advisors,
Professor Dr. Takeshi Yamauchi from Niigata University, Japan and Associate
Professor Dr. Surasak Watanesk from Chiang Mai University, Thailand for their kind
and enthusiastic supervision, invaluable guidance, corrections and constant
encouragement throughout the course of this research project.
I would also like to thank Professor Dr. Tamesue Shingo from Niigata
University, Japan and Associate Professor Dr. Ruangsri Watanesk from Chiang Mai
University, Thailand for their supports, advice and useful suggestions at various stages
during the work.
Financial support from the Japan Student Services Organization (JASSO),
Graduate School of Science and Technology, Niigata University, Japan, the Center of
Excellence for Innovation in Chemistry (PERCH-CIC), Office of the Higher Education
Commission (OHEC), Ministry of Education, Thailand, is gratefully acknowledged.
Thanks to the National Research University Project under Thailand’s OHEC, Material
Science Research Center, Faculty of Science and the Graduate School, Chiang Mai
I
University, Thailand, for partial financial supports. I also wish to express my sincere
gratitude to Graduate School of Science and Technology, Niigata University, Japan and
the Department of Chemistry, Faculty of Science, Chiang Mai University, Thailand for
providing me with laboratory and library facilities which have made this study possible.
In addition, I also owe my thanks to group members of Professor Takeshi
Yamauchi Research Laboratory and members of the Chemical Modification of Natural
Fibrous Materials Research Group for their friendship, helps, joy and sharing many
experiences in the laboratory providing the family type of warm and comfortable
feeling.
Finally, I would like to thank my parents and all my family members for their
forever love, care, and support. I would like to give the credit of my success to them.

Pusita Kuchaiyaphum

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Thesis Title An Approach for Preparing a Bio-Hybrid Material
with Special Water Affinity from Poly(vinyl
alcohol), Rice Starch and Silk Fibroin for Wound
Dressing Application
Author Ms. Pusita Kuchaiyaphum
Advisory Committee Prof. Dr. Takeshi Yamauchi Advisor
Assc. Prof. Dr. Surasak Watanesk Advisor
Assc. Prof. Dr. Ruangsri Watanesk Co-advisor

ABSTRACT
A hybrid material composing of polyvinyl alcohol (PVA), rice starch (RS) and
silk fibroin (SF) with opposite water affinity on each surface was successfully prepared.
The hybrid material was prepared by placing PVA/RS/SF hydrogel onto glycerol-
modified PVA/RS/SF film and leaving them to adhere. SF content in the hydrogels was
optimized first by mixing various SF amounts to a mixture of PVA:RS (2:1 by weight).
The 8.00 part per hundred of polymer (php) of SF was an appropriate concentration
revealed by the maximum values of gel fraction and percent porosity. This SF content
caused the blend to exhibit the highest water saturation and best mechanical properties.
The glycerol-modified hydrophobic film with the same PVA/RS/SF composition was
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prepared and found that the water contact angle of the film had increased approximately
three times after water soaking. The hybrid material was then prepared and
characterized. As evidenced by physical appearance and SEM images, the interfaces
between layers became homogeneous after 30 h layering time. Water contact angle
values pointed out the hydrophilic nature of the hydrogel surface, while the film surface
was hydrophobic. Coupling of the hydrogel with the film improved overall mechanical
properties as indicated by stress and % elongation at break.

IV
CONTENTS
Page
Acknowledgement i
Abstract iii
List of Tables ix
List of Figures xi
List of Abbreviations and Symbols xiii
Chapter 1 Introduction 1
1.1 Wound dressing 1
Types of wound dressing 2
1.2 Poly (vinyl alcohol) 3
PVA hydrogel 4
- Freezing and thawing method 5
- Gelation of PVA by freezing and thawing method 6
- Characteristic of PVA gel fabricated by freezing and 6
thawing method
1.3 Silk 7
Structure of silk protein 8
Silk fibroin 10
Page
V
1.4 Starch 12
Rice starch 13
1.5 Objective of this thesis 16
Chapter 2 Experimental 17
2.1 Chemicals, materials and equipment 17
2.1.1 Chemicals and materials 17
2.1.2 Equipments 18
2.2 Preparation of materials and solutions 19
2.2.1 Preparation of silk fibroin powder 19
2.2.2 Preparation of solutions 19
2.3 Procedures 20
Part I: Preliminary study: Preparation of PVA, RS and PVA/RS hydrogels 20
I.1 Preparation of PVA, RS and PVA/RS hydrogels 20
Part II: Preparation and characterization of PVA/RS/SF hydrogels 21
II.1 Preparation of PVA/RS/SF hydrogels 22
II.2 Characterization of PVA/RS/SF hydrogels 22
II.2.1 Percentages of gel fraction and water absorption 22
II.2.2 Mophology 23
II.2.3 Hydrogel porosity 23
II.2.4 Mechanical properties 24

VI
Page
Part III: Preparation and characterization of 24
glycerol modified PVA/RS/SF films
III.1 Preparation of glycerol modified PVA/RS/SF films 24
III.2 Characterization of glycerol modified PVA/RS/SF films 25
III.2.1 Film hydrophobicity 25
III.2.2 Mechanical properties 25
Part IV: Preparation and characterization of PVA/RS/SF hybrid material 26
IV.1 Preparation of PVA/RS/SF hybrid material 26
IV.2 Characterization of PVA/RS/SF hybrid material 26
Chapter 3 Results and Discussion 27
Part I: Preliminary study: Preparation of PVA, RS and PVA/RS hydrogels 28
Part II: Preparation and characterization of PVA/RS/SF hydrogels 31
II.1 Percentages of gel fraction and water absorption 31
II.2 Morphology 33
II.3 Hydrogel porosity and mechanical properties 34
Part III: Preparation and characterization of 35
glycerol modified PVA/RS/SF films
III.1 Film hydrophobicity 35
III.2 Mechanical properties 38
Part IV: Preparation and characterization of PVA/RS/SF hybrid material 39
VII
IV.1 UV-light exposing 39
Page
IV.1.1 Morphology 39
IV.1.2 Porosity, hydrophilicity, hydrophobicity and 40
mechanical properties
IV.2 Simple placing (Self healing) 41
IV.2.1 Physical appearance and interfacial morphology 41
IV.2 Gel fraction, porosity and mechanical properties 43
Chapter 4 Conclusion 46
References 49
List of publication 59
Curriculum Vitae 60

VIII
LIST OF TABLES
Page
Table 2.1 Chemicals 17
Table 2.2 Materials 18
Table 2.3 Equipments 18
Table 2.4 Solution preparation 20
Table 2.5 PVA samples with various % hydrolysis and molecular weight 21
used for preparing PVA and PVA/RS hydrogels
Table 3.1 The physical appearances of PVA hydrogels with various 2 9
% hydrolysis and molecular weight after freezing-thawing at
various cycles
Table 3.2 The physical appearances of PVA/RS hydrogels with various % 30
hydrolysis and molecular weight after freezing-thawing at various
cycles
Table 3.3 Gel fraction (G) of PVA/RS/SF hydrogel with various SF contents 31
Table 3.4 Porosity and mechanical properties of PVA/RS/SF hydrogels with 34
various SF contents
Table 3.5 Porosity, water contact angle and mechanical properties of 40
PVA/RS/SF hybrid materials with various UV-light exposure
periods
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