Marine, Waterborne, and Water-Resistant Polymers: Chemistry and Applications

Preface

This book focuses on the chemistry of marine polymers, waterborne polymers, and water resistant polymers, as well as special applications of these materials.

After an introductory section on the general aspects of the field, the types and uses of these polymers are summarized, followed by an overview of some testing methods.

In passing, as it so happens in the literature for these types of polymers, a lot of special organic compounds are used which for the ordinary organic and polymer chemist are not too familiar. Therefore, the structures of these organic compounds are reproduced in many of the figures.

The text focuses on the literature of the past decade. Beyond education, this book may serve the needs of industry engineers and specialists who have only a passing knowledge of these issues, but need to know more.

How to Use This Book

Utmost care has been taken to present reliable data. Because of the vast variety of material presented here, however, the text cannot be complete in all aspects, and it is recommended that the reader study the original literature for more complete information.

The reader should be aware that mostly US patents have been cited where available, but not the corresponding equivalent patents of other countries. In particular, in this field of science, most of the original patents are of Japanese origin.

For this reason, the author cannot assume responsibility for the completeness, validity or consequences of the use of the material presented here. Every attempt has been made to identify trademarks; however, there were some that the author was unable to locate.

Index

There are three indices: an index of acronyms, an index of chemicals, and a general index. In the index of chemicals, compounds that occur extensively, e.g., acetone, are not included at every occurrence, but rather when they appear in an important context. When a compound is found in a figure, the entry is marked in boldface letters in the chemical index.

Acknowledgements

I am indebted to our university librarians, Dr. Christian Hasenhüttl, Dr. Johann Delanoy, Franz Jurek, Margit Keshmiri, Dolores Knabl, Friedrich Scheer, Christian Slamenik, Renate Tschabuschnig, and Elisabeth Groß for their support in literature acquisition. In addition, many thanks to the head of my department, ProfessorWolfgang Kern, for his interest and permission to prepare this text.

I also want to express my gratitude to all the scientists who have carefully published their results concerning the topics dealt with herein. This book could not have been otherwise compiled.

Last, but not least, I want to thank the publisher, Martin Scrivener, for his abiding interest and help in the preparation of the text. In addition, my thanks go to Jean Markovic, who made the final copyedit with utmost care.

Johannes Fink

Leoben, July 15, 2015

Chapter 1

Marine Polymers

An overview of the methods, applications, and products of marine biotechnology has been presented (1). A large portion of the surface of the earth is covered by the ocean. Therefore, more than 80% of living organisms can be found in aquatic ecosystems. Thus, these organisms constitute a rich reservoir for various chemical materials and biochemical processes.

The literature for marine natural products has been extensively reviewed (2–4). Compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, mollusks, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms have been collected. Also, biosynthetic studies, and syntheses that lead to the revision of structures or stereochemistries, have been dealt with (4).

Biochemical materials and processes from marine sources make these materials available to applications in pharmaceuticals, cosmeceuticals or nutraceuticals, as well as for the production of biopolymers, bioenergy and biofuels (1). Also, biomaterials from marine-origin biopolymers have been reviewed (5).

1.1 Marine Microbes

The marine microbial biosphere is a large resource of biotechnological interest. The potential of marine microbes in biotechnology has been reviewed (6).

The biotechnological potential ranges from the synthesis of bioactive molecules to the production of biofuels, cosmeceuticals, nutraceuticals, and biopolymers.

Marine microbes can be used for biomedical purposes and also for the degradation of pollutants. Marine viruses have a great biotechnological potential. Marine archaea have been exploited for the isolation of enzymes. Also, bacteria and microbial eukaryotes are of importance for biotechnological uses (6).

1.2 Marine Microgels

The ocean plays a critical role in the global carbon cycle (7). It handles around 50% of the global primary production, yielding the world’s largest stock of reduced organic carbon (ROC) that supports one of the world’s largest biomasses. However, the mechanisms whereby ROC becomes mineralized remain unresolved. A review has been presented that focuses on laboratory and field observations that of dissolved organic carbon (DOC) self-assembles, and the formation of self-assembled microgels (SAGs).

Self-assembly has approximately 10% yield, generating an estimated global seawater SAG budget of some 1016 g carbon. The transects at depths of 10 to 4,000 m reveal concentrations of 10⁶ to 3 × 10¹² SAG l–1, thus respectively forming an estimated ROC stock larger than the global marine biomass (7).

Because hydrogels have 1% solids, i.e., 10 gl–1, whereas seawater DOC reaches only 10–3 gl–1, SAGs contain 10⁴ more bacterial substrate than seawater.

For this reason, microgels represent an unsuspected and huge micron-level ocean patchiness that could profoundly influence the passage of DOC through the microbial loop, with ramifications that may scale to global cycles of bioactive elements (7).

1.3 Polymer Production from Marine Algae

The broad class of polymeric materials includes polymers with excellent processability, chemical resistance, and mechanical properties. These properties allow polymers to be used to produce extrusion molded articles, injection molded articles, hollow molded articles, films, sheets, among many others.

Numerous polymers are derived from petroleum and natural gas. Actually, the market prices for these fossil fuels are increasing due to a number of factors, including a depletion of easily accessible deposits, growth of emerging economies, political instabilities, and environmental concerns. Therefore, polymer production methods that do not rely on fossil fuels are desirable (8).

The production of biopolymers from algae has already been described in 1975 (9). Long-chain polymers with flocculating properties have been produced.

The special issues of algae have been summarized (10). Algae are a very large and diverse group of eukaryotic organisms, ranging from unicellular genera and the diatoms to multicellular forms. An eukaryote is an organism whose cells contain a nucleus and other organelles enclosed within membranes (11).

Algae can produce 10–100 times more mass then terrestrial plants in the course of a year. Algae also produce oils and starches that may be converted into biofuels. Algae useful for biofuel production are also microalgae, consisting of small, often unicellular, types.

These algae can grow almost everywhere, but are most commonly found at latitudes between 40 degrees north and 40 degrees south. The algae can grow rapidly in nearly any environment, with almost any kind of water, including marginal areas with a limited or poor quality water. Micrographs from the algae are shown in Figure 1.1.

Figure 1.1 Micrographs from Isochrysis sp. (8): (a) merge of (c) and (d), (b) phase contrast image, (c) Nile Red stained image, (d) chlorophyll autofluoresence.

It has been found that certain algae species of the Isochrysis family produce polyunsaturated long-chain alkenones. In the studies, methyl and ethyl alkenones with 35–40 carbons having 2–4 double bonds have been detected.

Lipid-producing algae can include a wide variety of algae. Algae are classified as follows: diatoms are bacillariophytes, green algae are chlorophytes, blue-green algae are cyanophytes, golden-brown algae are chrysophytes, and phylum of algae are haptophytes. Most common algae are listed in Table 1.1.

Table 1.1 Lipid-producing algae.

Methods have been developed for producing polymers from algae. Such methods comprise (8):

1. Culturing an alkenone-producing alga under a growth condition sufficient to produce alkenones within the alga,

2. Optionally chemically modifying the alkenones to produce alkenone derivatives, such as acrylic acids, acrylic esters, alkenes, vinyl chloride, vinyl acetate, diacids, diamines, diols, or lactic acid, and

3. Polymerizing the alkenones or alkenone derivatives.

The alkenone-producing alga can be a species of the Isochrysis family, such as Isochrysis galbana, Isochrysis sp. T-Iso, and Isochrysis sp. C-Iso. The alkenones of the alga should be alkenones with a number of carbons of 35–40. The alkenones may be converted into hydrocarbons by catalytic hydroprocessing.

Eventually, the alkenones can be converted into a liquid fuel such as diesel and gasoline. Likewise, the alkenones may be processed into a gaseous fuel such as synthesis gas or methane, propane, and butane. The alga may also deliver fatty acid methyl esters.

The growth condition for culturing the alga may include a stationary growth phase, a high temperature, sufficient light, and nutrient limitation. The algae can also be directly converted into methane via a hydrothermal gasification process (8).

1.3.1 Recovery of Lipids Algae

Algae store lipids inside the cell body, sometimes but not always in vesicles (8). The lipids can be recovered in various ways, including solvents, heat, pressure, or depolymerization, such as by biologically breaking the walls of the algal cell or oil vesicles.

At least one of three types of biological agents may be used to release algae energy stores, for example, enzymes such as cellulase or glycoproteinase, structured enzyme arrays or system such as a cellulosome, a viral agent, or a combination of these agents.

A cellulase is an enzyme that breaks down cellulose, especially in the wall structures. A cellulosome is an array or sequence of enzymes or cellulases which is more effective and faster than a single enzyme or cellulase. In both cases, the enzymes break down the cell wall or lipid vesicles and release lipids from the cell.

Cellulases used for this purpose may be derived from fungi, bacteria, or yeast. Examples include cellulase produced by fungus Trichoderma reesei and many genetic variations of this fungus, cellulase produced by the bacteria genus Cellulomonas, and cellulase produced by the yeast genus Trichosporon.

A glycoproteinase provides the same function as a cellulase, but is more effective on the cell walls of microalgae, many of which have a structure more dependent on glycoproteins than cellulose (8).

1.3.2 Conversion of Algal Lipids into Hydrocarbons

A process for converting the algal alkenones into hydrocarbons is catalytic hydroprocessing, or cracking (8). The catalytic hydroprocessing technology is well known in the art of petroleum refining and generally refers to converting at least large hydrocarbon molecules into smaller hydrocarbon molecules by breaking the carboncarbon bonds (12).

The long chains of carbon in the alkenones produced by algae can be used to produce a wider range of biofuels or lubricating oils than those derived from glycerides (8).

1.3.3 Conversion of Algal Lipids into Polymers

The algal lipids can be used as feedstock in the industrial chemical field, particularly in the manufacture of polymers. The algal lipids can be polymerized, either directly or after some chemical modification (8).

Also, the algal lipids can be pyrolyzed or cracked into smaller molecules to permit the generation of standard monomers such as acrylic acids and esters, alkenes, vinyl chloride, vinyl acetate, diacids, diamines, diols, lactic acid, and others (8).

1.3.4 Crosslinking of Phenolic Polymers

It has been shown that a phenolic polymer extracted from Fucus serratus can be crosslinked using a vanadium-dependent bromoperoxidase (13). The methanol extracted phenolic polymer was adsorbed onto a quartz crystal sensor and the crosslinking was initiated by the addition of bromoperoxidase, KBr, and H2O2.

The decreased dissipation upon addition of the crosslinking agents, as measured with the quartz crystal microbalance with the quartz crystal microbalance dissipation (QCM-D), was interpreted as intramolecular crosslinks being formed between different phloroglucinol units in the phenolic polymer.

With surface plasmon resonance, it was shown that no desorption occurred from the sensor surface during the crosslinking reaction. UV/VIS spectroscopy verified the results achieved with QCM-D that all components, i.e., bromoperoxidase, KBr, and H2O2, were necessary in order to achieve intramolecular oxidative crosslinking of the polymer (13).

1.4 Marine Bioadhesive Analogs

Nature has evolved materials that possess mechanical properties surpassing many manmade composites. A nanostructured composite film that takes advantage of two different natural materials has been prepared (14). These materials are layered nacre and the marine adhesive of mussels.

L-3,4-Dihydroxyphenylalanine molecules impart an unusual adhesive strength to a clay composite and the hardening mechanism found in the natural cement plays an equally important role in the strengthening of the nanostructured nacre (14).

The in-situ molecular physicochemical characterization of bioadhesives at solid or liquid interfaces has been reviewed (15). The adhesion strategies that lie at the root of marine biofouling have been elucidated. Three major fouling organisms have been assessed: mussels, algae and barnacles.

The dispersal of these organisms, their colonization on the surfaces, and ultimately their survival are critically dependent on the ability of the larvae or spores of the organisms to locate a favorable settlement site and undergo metamorphosis. In this way their sessile existence is initiated.

Differences in the composition of the adhesive secretions and the strategies employed for their temporary or permanent implementation between the larval and adult life stages are obvious.

Until now, only a few adhesive secretions from marine fouling organisms have been adequately described in terms of their chemical composition. The presence of certain recurrent functional groups, specifically catechol, carboxylate, monoester-sulphate and -phosphate are used for this purpose. The binding modes of such functionalities to wet mineral and metal oxides surfaces have been described in detail.

A plausible explanation for the propensity of these adhesive functionalities to bind to hydrous metal oxide surfaces has been based on the basis of the hard and soft acids and bases principle, Hofmeister effects and entropic considerations.

From the in-situ analysis of marine organism bioadhesives and adsorption studies of functionalities relevant to the bioadhesion process, insights suitable for antifouling strategies and the synthesis of durable adhesive materials can be obtained (15).

1.5 Medical Applications

Marine organisms are constituted by materials with a vast range of properties and characteristics that may justify their potential application within the biomedical field (16). Moreover, assuring the sustainable exploitation of natural marine resources, the valorization of residues from marine origin, like those obtained from food processing, constitutes a highly interesting platform for the development of novel biomaterials, with both economic and environmental benefits.

In the last decade, many different biomaterials, like various types of polymers and bioactive ingredients, have been identified, isolated, and characterized. These biomaterials can be used in controlled drug delivery, tissue engineering, and diagnostic devices (17).

In this perspective, an increasing number of different types of compounds can be isolated from aquatic organisms and transformed into profitable products for health applications, including controlled drug delivery and tissue engineering devices.

The issues of marine structural proteins in biomedicine and tissue engineering have been reviewed (18). Actually, the development of biocompatible composites and vehicles of marine biopolymer origin for growth, retention, delivery, and differentiation of stem cells is of crucial importance for regenerative medicine.

Also, the current techniques for the isolation and characterization of polysaccharides, proteins, glycosaminoglycans and ceramics from marine raw materials have been reviewed (16). Specific compound classes for medical applications are listed in Table 1.2.

Table 1.2 Marine materials for medical applications (16).

Marine-derived bioactive compounds for breast and prostate cancer treatment have been reviewed (19). Marine-derived natural bioactive products, isolated from aquatic fungi, cyanobacteria, sponges, algae, and tunicates, have been found to exhibit various anticancer activities including anti-angiogenic, anti-proliferative, inhibition of topoisomerase activities and induction of apoptosis.

1.5.1 Metalloproteinases

Matrix metalloproteinases