novel functional materials from renewable lipids: amphiphilic antimicrobial polymers and latent ...

261 Pages·2016·18.57 MB·English

NOVEL FUNCTIONAL MATERIALS FROM
RENEWABLE LIPIDS: AMPHIPHILIC
ANTIMICROBIAL POLYMERS AND LATENT
HEAT THERMAL ENERGY STORAGE

A Thesis Submitted to the Committee on Graduate Studies in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy in the Faculty of Arts and Science

TRENT UNIVERSITY
Peterborough, Ontario, Canada
© Copyright Michael Christopher Floros 2015
Materials Science Ph.D. Graduate Program
September 2015
Abstract
Novel Functional Materials from Vegetable Oils: Amphiphilic Antimicrobial Surfaces and
Latent Heat Thermal Energy Storage

MICHAEL CHRISTOPHER FLOROS

Vegetable oils represent an ideal and renewable feedstock for the synthesis of a variety of
functional materials. However, without financial incentive or unique applications
motivating a switch, commercial products continue to be manufactured from
petrochemical resources. Two different families of high value, functional materials
synthesized from vegetable oils were studied. These materials demonstrate superior and
unique performance to comparable petrochemical analogues currently on the market.
In the first approach, 3 amphiphilic thermoplastic polytriazoles with differing
lipophilic segment lengths were synthesized in a polymerization process without solvents
or catalysts. Investigation of monomer structure influence on the resultant functional
behaviour of these polymers found distinctive odd/even behaviour reliant on the number
of carbon atoms in the monomers. Higher concentrations of triazole groups, due to shorter
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CH chains in the monomeric dialkynes, resulted in more brittle polymers, displaying
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higher tensile strengths but reduced elongation to break characteristics. These polymers
had similar properties to commercial petroleum derived thermoplastics. One polymer
demonstrated self-assembled surface microstructuring, and displayed hydrophobic
properties. Antimicrobial efficacy of the polymers were tested by applying concentrated
bacterial solutions to the surfaces, and near complete inhibition was demonstrated after 4
hours. Scanning electron microscope images of killed bacteria showed extensive membrane
damage, consistent with the observed impact of other amphiphilic compounds in
literature. These polytriazoles are suited for applications in medical devices and implants,
where major concerns over antibiotic resistance are prevalent.
In the second approach, a series of symmetric, saturated diester phase change
materials (PCMs) were also synthesized with superior latent heat values compared to
commercial petrochemical analogues. These diesters exhibit melting temperatures between
39 °C and 77 °C, with latent heats greater than 220 J/g; much greater than paraffin waxes,
which are currently the industry standard. Assessment of the trends between differing
monomer lengths, in terms of number of CH groups of the 24 diesters synthesized
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exhibited structure/function dependencies in latent heat values and phase change
temperatures, providing an understanding of the influence of each monomer on PCM
thermal properties. A synthetic procedure was developed to produce these PCMs from a
low value biodiesel feedstock. Application of these PCMs in the thermoregulation of hot
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beverages was demonstrated using a representative diester. This PCM cooled a freshly
brewed hot beverage to a desired temperature within 1 minute, compared to 18 minutes
required for the control. Furthermore, the PCM kept the beverage within the desired
temperature range for 235 minutes, 40 % longer than the control.

Keywords: Phase Change Material, Antimicrobial Surface, Click Chemistry, Polytriazole,
Renewable, Green Chemistry
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Preface
Petrochemical resources are extensively used to produce materials we interact with on a
daily basis. However, petrochemicals are finite, non-renewable compounds and as demand
for them grows, supply is dwindling, resulting in cost increases. Extraction and
consumption of petrochemicals is also a leading cause of global warming. We are entering
a period where the adverse effects of climate change are becoming dire; public opinion and
policy makers are beginning to take notice. Eventually, public policy and/or economic
factors will force our economy to shift away from an oil-dominated model. Renewable
lipids represent an ideal alternative feed stock for current and future materials, in part due
to their safety, unique chemistries, low cost and exciting technologies in development
situated to increase their production.
This work focuses on the synthesis and characterization of novel materials from vegetable
oils, which are superior or unique to products currently on the market. We hope that the
introduction of novel materials for which no superior petrochemical analogues exist will
expedite commercial acceptance and support the shift to renewable materials.
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Acknowledgements
Firstly, I would like to express my gratitude to my advisor Professor Suresh Narine for his
supervision in both my undergraduate and graduate career. Had he not provided me with
ample resources and freedom to pursue multiple research directions, this work would not
be possible. Our discussions on an array of topics have influenced my understanding of
issues beyond just the sciences. I would not be the scientist I am today without his support
and influence.
I would also like to thank my committee members, Professor Steven Rafferty and
Professor Yuri Bolshan. Suggestions and discussions with them over the course of my work
have greatly contributed to the directions of this thesis. My decision to attend graduate
school was largely due to ideas developed in courses enthusiastically taught by Professor
Rafferty, who was always available to talk after class.
Both Dr. Shaojun Li and Dr. Laziz Bouzidi contributed greatly to my understanding
of materials science, scientific writing and study design. Everyone in the Biomaterials group
is deserving of mention as well. In particular, Latchmi Raghunanan, Michael Tessier,
Avinaash Persaud and Prasanth Pillai could be counted on anytime I needed someone to
help rephrase a sentence, switch fractions during a long column chromatography session
or be part of numerous provoking discussions.
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Without the support, motivation and assistance of Janaína Bortolatto, especially
during my time in Brazil, this work would not be possible. Professor Osmir B. Oliveira Jr,
Professor Hernane Barud and Professor Sergio L. Salvador deserve mention for dedicating
significant time and resources to assisting me. They welcomed me into their laboratories
and lives, making me feel at home during my stay in Brazil. Professor Salvador’s
microbiological training, suggestions and facilities were especially instrumental.
Most importantly, I would like to thank my parents Steve Floros and Trish Back.
Thank you for motivating me to pursue my ambitions. I can honestly say I do not know
where I would be right now without your continued and unwavering support.

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Table of Contents
NOVEL FUNCTIONAL MATERIALS FROM RENEWABLE LIPIDS: AMPHIPHILIC
ANTIMICROBIAL POLYMERS AND LATENT HEAT THERMAL ENERGY
STORAGE ......................................................................................................................... i
Abstract ............................................................................................................................ii
Preface .............................................................................................................................. v
Acknowledgements ......................................................................................................... vi
Table of Contents .......................................................................................................... viii
List of Figures ................................................................................................................ xiv
List of Tables ............................................................................................................... xviii
List of Schemes .............................................................................................................. xix
List of Abbreviations and Symbols ............................................................................... xxi
1 Introduction ............................................................................................................. 1
1.1 Lipids as Renewable Feedstocks ....................................................................... 2
1.2 Renewable Materials from Lipids ................................................................... 9
1.2.1 Triglyceride Based Materials .................................................................................. 9
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Fatty Acid Based Materials ................................................................................... 13
1.3 Materials for Energy Storage ................................................................................ 18
1.3.1 Phase Change Materials ........................................................................................ 18
1.3.1.1 Paraffin waxes ................................................................................................ 21
1.3.1.2 Lipid-derived PCMs ..................................................................................... 23
1.4 Antimicrobial Materials ................................................................................ 28
1.4.1 Antibiotic Resistance ............................................................................................. 31
1.4.2 Amphiphilic Antimicrobials ................................................................................ 35
1.5 Hypotheses and Objectives ............................................................................ 39
1.5.1 Phase Change Materials ........................................................................................ 40
1.5.2 Thermoplastic Polytriazoles and Antimicrobial Materials .............................. 42
2 Phase Change Materials ......................................................................................... 45
2.1 Saturated Linear Diesters from Stearic Acid as Renewable Phase Change
Materials ......................................................................................................................... 46
Highlights ............................................................................................................................ 47
2.1.1 Abstract ................................................................................................................... 48
2.1.2 Introduction ........................................................................................................... 49
2.1.3 Materials and methods .......................................................................................... 50
2.1.4 Results and discussion .......................................................................................... 52
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2.1.5 Conclusion .............................................................................................................. 59
2.1.6 Acknowledgements ............................................................................................... 60
2.2 Latent Heat Storage Using Renewable Saturated Diesters as Phase Change
Materials ......................................................................................................................... 61
Highlights ............................................................................................................................ 62
2.2.1 Abstract ................................................................................................................... 63
2.2.2 Introduction ........................................................................................................... 65
2.2.3 Materials and methods .......................................................................................... 70
2.2.3.1 Materials ......................................................................................................... 70
2.2.3.2 Preparation of the PCMs ............................................................................. 70
2.2.3.3 Characterization ............................................................................................ 72
2.2.3.4 PCM Modified Beverage Container ........................................................... 72
2.2.3.5 Beverage Temperature Retention Test ....................................................... 73
2.2.4 Results and Discussion .......................................................................................... 75
2.2.4.1 Green Synthesis ............................................................................................. 75
2.2.4.2 Thermal Transition Properties .................................................................... 79
2.2.4.3 Hot Beverage Temperature Control and Retention ................................. 83
2.2.5 Conclusion .............................................................................................................. 86
2.2.6 Acknowledgements ............................................................................................... 88
3 Thermoplastic Polytriazoles .................................................................................. 89
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