纤维素纳米晶/氧化锌杂化材料的结构设计及其生物聚酯膜的改性研究

摘要

Biodegradable polyesters are a relevant candidate in the field of biomedical applications suchas drug delivery, wound dressings, tissue engineering owing to their suitable properties to supportcellular growth and proliferation.However, the applications of biodegradable polyesters in thebiomedical are limited due to their low degradation rate, uncontrollable degradation for manyclinical applications, poor mechanical and thermal properties.Therefore by understanding thecombined effects of inorganic ZnO nanoparticles and biomass cellulose nanocrystals (CNCs) frommost abundant natural cellulose resources as UV absorber and antibacterial agents into biopolyesterespecially (poly (3-hydroxybutyrate-co-3-hydroxy valerate, PHBV) matrix with or without theaddition of polyethylene glycol (PEG) as organic phase change materials could provide newprospects to the sustainable use of nanotechnology and nanocomposites with improvement in thethermal and mechanical properties for potential applications in antibacterial wound dressings, UVshielding materials, drug delivery, and thermal energy storages fields.In this dissertation, a seriesof ultra-high performance biopolyester nanocomposites were successfully fabricated by welldispersed of CNC-ZnO nanohybrids with modulated contents as nanofillers into bio-polyester(poly (3-hydroxybutyrate-co-3-hydroxy valerate, PHBV) matrix.The impact of nanofillerscontent and fabrication techniques on their structures designs and properties were discussed indetails.This research can provide a theoretical basis and technical guidance for the preparation andfabrication of these novel biopolyester nanocomposites with multi-functional properties forpotential uses as biomedical biomaterials.The main results are summarized as follows: 1) Green synthesis of sheet-like cellulose nanoerystal-zinc oxide nanohybrids withmultifunctional performance through one-step hydrothermal method.In this study, wereport novel sheet-like cellulose nanocrystal-zinc oxide nanohybrids (CNC-ZnO) by using aone-step hydrothermal method.Various concentrations of Zn2+ ions were functionalized inCNC surface and a possible mechanism for the formation of CNC-ZnO nanohybrids withhexagonal sheet-like structure converted to the flower-like structure was also presented. Additionally, the sheet-like CNC-ZnO5.0 showed good antimicrobial activity, excellentthermal stability and high photocatalytic activity of 95.21％ of MB dye was decomposed after200 min under UV light irradiation.More significantly, the CNC-ZnO5.0 nanohybrid can berecycled three times with good Turnover frequency values (TOF).Compared to pure CNC, themaximum degradation temperature (Tmax) of sheet-like nanocrystal-Zinc oxide nanohybridwith the addition of 5 mmol Zn2+ ions (CNC-ZnO50) nanohybrid was improved by 23.1 ℃,and its limiting oxygen index increased up to 49.6％.This work provides a simple preparationprocedure of sheet-like CNC-ZnO nanohybrids with good antimicrobial, photocatalytic andthermal properties for attractive applications as biomedical materials and flame-retardants. 2) Sheet-like cellulose nanocrystal-ZnO nanohybrids as multifunctional reinforcing agentsin biopolyestercomposite nanofibers with ultrahigh UV-Shielding and antibacterialperformanees.The uses of inorganic metal oxide and ZnO nanohybrids as UV absorbershave potential to increase the production of UV-protective textile, which will also overcomethe drawbacks of organic molecules and prevent negative impacts on human health andenvironment.In this work, sheet-like cellulose nanocrystal-Zinc oxide (CNC-ZnO)nanohybrid was successfully developed by a one-step hydrothermal method.The obtainedCNC-ZnO nanohybrids as UV absorber and antibacterial agents were introduced intobiopolyester (poly (3-hydroxybutyrate-co-3-hydroxyvalerate, PHBV) by usingelectrospinning process.The addition of sheet-like CNC-ZnO can greatly enhance PHBVthermal stability and crystallization ability.In addition, excellent antimicrobial ratios ofEscherichia coli and Staphylococcus aureus, and high absorbency of solution A (9.82 g/g)were obtained for the composite nanofibers with 5 wt ％ CNC-ZnO.Moreover, most of theUV irradiations were blocked out for both UVA (99.72％) and UVB (99.95％) with high UPFvalue of 1674.9 in the resulting composite nanofibers with 9 wt ％ CNC-ZnO.This studyprovides a novel method to produce sheet-like CNC-ZnO with multifunctional properties andits nanocomposite for potential uses as wound dressings and other functional biomaterials. 3) In vitro degradation and possible hydrolytic mechanism of PHBV nanocomposites byincorporating cellulose nanocrystal-ZnO nanohybrids.Fabrication and characterization ofbiodegradable nanocomposites based on poly (3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV) matrix reinforced with cellulose nanocrystal (CNC-ZnO) nanohybrids via simplesolution casting process for possible use as antibacterial biomedical materials is reported.Theobtained nanocomposites exhib

目录

声明

Acknowledgements

Abstract

Table of contents

List of Figures

List of Tables

Chapter 1．Introduction

1．1．Introduction

1．2．Biodegradable polymer

1．2．1．Polyhydroxyalkanoates polymers(PHAs)

1．2．2．Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV)

1．2．3．The properties of PHBV

1．2．4． Applications of PHBV nanoeomposites

1．3．Nanocellulose materials

1．3．1． Cellulose nanocrystals(CNCs)

1．3．2． Cellulose nanofibrils(CNFs)

1．3．3． Cellulose nanoerystals as nanofiilers based biopolymer nanoeomposites and their potential applications

1．3．4．Processing of nanoeellulose based nanocomposites

1．4．Cellulose nanocrystals／Zinc oxide composites(CNCs／ZnO)

1．5．Synthesis of nanocellulose／Zinc oxide composite(NCs／ZnO)

1．5．1． Application of cellulose nanocrystal／ZnO composites

1．6．Outline of the dissertation

1．7．Experimental design of the dissertation

Refefences

Chapter 2．Green synthesis of sheet-like cellulose nanocrystal-zinc oxide nanohybrids with multifunctional performance through one-step hydrothermal method

2．1． IntroductiOn

2．2． Experimental section

2．2．1． Materials

2．2．3． Charaeterizations

2．3． Results and discussions

2．3．1． Morphology and mierostructures

2．3．2． Crystal structure

2．3．3． Chemical structure and optical properties

2．3．4．Thermal properties

2．3．5． Antimicrobial properties

2．3．6．Photocatalytic activity

2．3．7．The apparent kinetic rate constants and Turnover frequeney(TOF)

2．4． Summary

References

Chapter 3．Sheet-like cellulose nanocrystal-ZnO nanohybrids as multifunctional reinforcing agents in biopolyester composite nanofibers with ultrahigh UV-Shielding and antibacterial performances

3．1． Introduction

3．2． Experimental section

3．2．1． Materials

3．2．3．Preparation and fabrication of composite nanofibers

3．2．4 Charaeterization

3．3． Results and discussions

3．3．1． Surface morphologies and mierostructures

3．3．2． Chemical structure

3．3．3．Thermal stability crystallization and melting behaviour

3．3．4． Spherulite Morphology

3．3．5． UV-Shielding Performance

3．3．6．The absorbency of solution A

3．3．7．Antimicrobial properties

3．4． Summary

References

Chapter 4．In vitro degradation and possible hydrolytic mechanism of PHBV nanocomposites by incorporating cellulose　nanocrystal-ZnO nanohybrids

4．1．Introduction

4．2． Experimental section

4．2．1． Materials

4．2．3．Preparation of the PHBV／CNC-ZnO nanocomposites

4．2．4． Charaeterization

4．3． Results and discussion

4．3．1． Morphology analysis

4．3．2． Chemical structure and optical properties

4．3．3．Thermal stability

4．3．4． Non-isothermal crystallization and melting behavior

4．3．5． Mechanical and barder properties

4．3．6． In vitro degradation and water contact angle

4．3．7． Antimicrobial properties

4．3．8． Morphological evolution of PHBV／CNC-ZnO nanoeomposites

4．3．9． Chemieal structure of PHBV／CNC-ZnO nanoeomposites after degradation in PBS solution

4．3．10．Thermal stability of PHBV／CNC-ZnO nanocomposites after degradation in PBS solution

4．4． Summary

Referenees

Chapter 5．Sun-light and thermo-sensitive responsive of PHBV phase change materials with functionalized Cellulose nanocrystal-ZnO nanohybrids for thermal energy storage and controllable drug release behavior

5．1． Introduction

5．2． Experimental section

5．2．1． Materials

5．2．2． Synthesis of CNC-ZaO

5．2．4． Electrospinning of PCF composite with Tetracycline hydrochloride (TH)

5．2．5．Thermal treatment of the PCF composites

5．2．6． Characterization

5．3． Results and discussion

5．3．1．The morphologies of phase change composite fiber(PCF)

5．3．2． Crystalline properties of PCF composites

5．3．3． Shape-stability of PCF composites

5．3．4． Chemical structures of PCF composite(FT-IR)

5．3．5．Thermal properties and supercooling extents of PCF composites

5．3．6．Thermal stability of PCF composites

5．3．7．Thermal reliability of PCF composites

5．3．8．Photothermal heat conversion of PCF composite

5．3．9．IR observation

5．3．10．In vitro drug release of drug loaded-PCF composites

5．4． Summary

References

Chapter 6．Conclusions and future works

6．1． Conclusions

6．2． Recommendations for future research

Appendix

Publications