Biomimetic functional surfaces with tailored wettability for water harvesting and anti-icing applications

Ph.D. Thesis

Biomimetic functional surfaces with tailored

wettability for water harvesting and anti-icing

applications

Nguyen Thanh Binh

Nano-Mechatronics

UNIVERSITY OF SCIENCE AND TECHNOLOGY

February 2019

Biomimetic functional surfaces with tailored

wettability for water harvesting and anti-icing 2019 Nguyen Thanh Binh

applications

Biomimetic functional surfaces with

tailored wettability for water harvesting

and anti-icing applications

Nguyen Thanh Binh

A Dissertation Submitted in Partial Fulfillment of Requirements

For the Degree of Doctor of Philosophy / Master

February 2019

UNIVERSITY OF SCIENCE AND TECHNOLOGY

Major of Nano-Mechatronics

Supervisor Hyuneui LIM

We hereby approve the Ph.D.

thesis of Nguyen Thanh Binh.

February 2019

Dr. Seungchul PARK

Chairman of Thesis Committee

Dr. Wandoo KIM

Thesis Committee Member

Dr. Changdae PARK

Thesis Committee Member

Dr. Junhee LEE

Thesis Committee Member

Dr. Hyoungsoo KIM

Thesis Committee Member

Dr. Youngdo JUNG

Thesis Committee Member

Dr. Hyuneui LIM

Thesis Committee Member / Supervisor

UNIVERSITY OF SCIENCE AND TECHNOLOGY

i

ACKNOWLEDGEMENT

This study is the result of my PhD thesis carried out at Nature-Inspired

Nanoconvergence Systems Department – Nano - Convergence Mechanical

Systems Research Division – Korea Institute of Machinery and Materials, Korea

with tremendous amount of support.

First, I would like to express my sincere gratitude to my advisor, Professor

Hyuneui. Lim, for giving me the opportunity to become her student at Nano￾mechatronics Department (UST), for giving me all the support, encouragement and

advice over past six and half years, and for spending long hours editing this thesis.

Her insightful guidance will be great inspiration for my future work in my

university afterwards.

I would like to thank Dr. Wandoo Kim for his valuable advice and

encouragement during my Ph.D’s degree. I would like to convey my great

gratefulness to the members of my dissertation defense committee, Dr.

Changdae Park, Dr. Junhee Lee, Dr. Hyoungsoo Kim, Dr. Youngdo Jung for

giving me all valuable comments and suggestions. Specifically, I would like to

thank Dr. Seungchul Park for his honest advice, valuable support and

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encouragement, who served as Chairman of my thesis committee.

I am also thankful to Dr. Duckgyu Lee for assistance regarding experiment

process and theoretical support when I started my PhD’s degree. A special thank

should be given to all my laboratory members, Dr. Sunjong Oh, Dr. Cholong Jung,

Dr. Seonggi Kim, Cheonji Lee, Gyuhyeon Han for their enthusiastic support.

Finally, I dedicate this thesis to my parents, my wife and my daughter for

their sincere love, outstanding support, for always beside and encouragement

during my PhD’s degree. This would have been impossible without them.

iii

ABSTRACT

iv

Biomimetic functional surfaces with tailored wettability

for water harvesting and anti-icing applications *

Biomimetic or Biomimicry refers to an approach that imitates nature’s time￾proved models, elements and strategies to solve sustainability human challenges.

In this study, we proposed the fabrication and investigation process on several bio￾inspired functional surfaces with tunable wettability towards solving specific

problems: water harvesting and anti-icing.

Water condensation is a phenomenon which refers to the changing physical

state of a matter from gaseous into liquid phase. The simplest process can be

imagined is water condensation on objects near earth’s surfaces such as: fog, dew,

frost, etc. In this work, we will focus on optimizing suitable surface morphology

for durable and high efficiency water harvesting performance. Several geometries

and surface energies will have been conducted on Aluminum (Al) plates in order

to maximize harvesting efficiency.

On the other hand, icing phenomenon refers to a process when liquid

transferring its physical state to solid phase. Ice accumulation on functional

surfaces had illustrated many bizarre effects and disadvantages in aviation,

industry and human activities. Several passive approaches including water

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repellency, Slippery Liquid-Infused Porous Surfaces (SLIPS) and unique design

structure in order to optimize anti-icing performance will be introduced throughout

this study.

Totally, we propose different physicochemical processes which arm to

manipulate surface wettability towards solving specific problems including water

condensation and anti-icing. The understanding about mechanism and fabrication

process is useful for designing water harvesting system and icephobic applications.

_________________________________

*A thesis submitted to committee of the University of Science and Technology in a partial fulfillment

of the requirement for the degree of Doctor of Science conferred in February, 2019.

초록

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자연모사 기능성 표면을 이용한 맞춤형 수분수집 및

방빙 응용 연구

자연모사 및 자연모방은 이미 자연의 진화에 의하여 증명된 문제해결법을 이

용하여 지속 가능한 인류의 도전과제를 해결하는 접근방식입니다. 본 연구는

표면의 젖음성을 제어할 수 있는 자연모사 기능성 표면의 제작 및 이에 대한

구체적인 적용인 수분수집 및 방빙의 응용을 제안합니다.

수분 응축이란 공기중의 수분이 기체 상태에서 액체 상태로 변화하는 현상을

말합니다. 이는 안개, 이슬, 서리 등과 같이 지구 표면에서 물이 응축되는 것

을 통해 손쉽게 확인이 가능합니다. 본 연구에서는 고내구성 및 고효율의 수

분수집을 위한 표면 구조 최적화에 집중을 하였습니다. 수분수집 효율 극대화

를 위한 다양한 형상 및 다양한 표면에너지를 가지는 알루미늄 기판을 제작하

였습니다.

또한, 빙결현상은 물이 액체 상태에서 고체상태로 변화하는 과정을 말합니다.

기능성 표면에 얼음이 쌓이는 현상의 경우 항공, 산업 및 사람들의 활동에 많

은 문제를 야기합니다. 본 연구에서는 발수특성 유도, 미끄러운 유체가 주입된

다공성 표면 (SLIPS) 및 독특한 구조 등 다양한 수동적인 접근방식을 연구하

였습니다.

따라서, 본 연구에서는 수분응축 및 방빙 등의 구체적인 현안을 해결하기 위

한 표면 젖음성 제어에 기반한 다양한 물리화학적 공정을 제안합니다. 이러한

메커니즘 및 공정과정에 대한 기반지식은 수분수집 및 방빙 관련 응용이 가능

합니다.

TABLE OF CONTENTS

ACKNOWLEDGMENTS………………………………………………....i

vii

ABSTRACT……………………………………………………...……....iii

ABSTRACT (KOREAN)………………………………………...…….....v

TABLE OF CONTENTS….………………..……………………………vi

LIST OF FIGURES………………………..……………………………...x

LIST OF TABLE……………………………………………...…..........xvii

1. INTRODUCTION..……..………………………..…...…………......1

1.1 Bio-Inspired Surfaces.……………………….…..….……….1

1.2 Water Harvesting……….….…..….………………..…..........4

1.3 Icing and Anti-icing …………………………....…………...8

2. BASIC THEORY…………...…………….....……….....……..........12

2.1 Wettability ………………..…………………..………….....12

2.1.1 Surface Tension………................……………..…….13

2.1.2 Superhydrophobic Surface………….…..…………...16

2.1.2.1 Wenzel State………….……………...……..17

2.1.2.2 Cassie-Baxter State……………….....…….…20

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2.1.3 Transition from Wenzel to Cassie-Baxter state…...…21

2.2 Nucleation Phenomenon…...…..……....…………………….23

2.2.1 Homogeneous Condensation……...………..………..25

2.2.2 Heterogeneous Condensation…….………………….27

2.3 Water Condensation………………………...………………..30

2.4 Icing and Anti-icing…………………………….………..…..33

2.4.1 Freezing Time…………………………....…………..37

2.4.2 Adhesion Strength……………………….…………..38

3. RESEARCH ON WATER HARVESTING……………….………...42

3.1 Current Research ………………..………….……………...42

3.2 Experimental methods………………………………..…...52

3.3 Results and Discussion………………..……..…….………..55

3.4 Conclusion ..............................................................................70

4. RESEARCH ON ANTI-ICING……………....…………..…………71

4.1 Current Research…………………………….………………71

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4.2 Effects of Morphology Parameters on Anti-icing Performance

of SH Surfaces………………………………………………82

4.2.1 Experimental methods……………………………….82

4.2.2 Results and Discussion………………………………86

4.2.3 Conclusion………………………………...…………96

4.3 Anti-icing on Slippery Liquid-Infused Porous Surface

(SLIPs)……………………………………………………....97

4.3.1 Experimental methods……………………………….97

4.3.2 Results and Discussion……………………..………103

4.3.3 Conclusion……………………….………………....114

4.4 Unique Structure for Multi-Functional Surface………...….115

4.4.1 Experimental methods……………..………..…….116

4.4.2 Results and Discussion……………..…..…………119

4.4.3 Conclusion………………………...……..…………131

5. CONCLUSION.………...………………………..……...……...….133

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REFERENCES .…………………………..….…………..........…….…136

LIST OF FIGURES

Figure 1.1 Summarization of bio-inspired functional surfaces and our approaches

in this study…………………………………………………...………...….......1