Adipamide Synthesis Essay
Your class has been writing a few argumentative essays here and there, and you have to admit … you’re getting pretty good at it. But now your instructor says that you need to take it a step further and write a synthesis essay.
The name might be a little intimidating, but don’t worry—I’ll be here to give you example topics and walk you through the steps to writing a great synthesis.
First … What Is a Synthesis Essay?
Before we jump right into generating ideas and writing your synthesis, it would be pretty useful to know what a synthesis essay actually is, right?
When you think about a synthesis essay, you can think of it as being kind of like an argumentative essay.
There is one key difference, though—your instructor provides you with the sources you are going to use to substantiate your argument.
This may sound a little bit easier than an argumentative essay. But it’s a different kind of thinking and writing that takes some time to get used to. Synthesis essays are all about presenting a strong position and identifying the relationships between your sources.
Don’t fall into the trap of simply summarizing the sources. Instead, make your point, and back it up with the evidence found in those sources. (I’ll explain this in more detail when we talk about the writing process.)
Many of your sources will probably have information that could support both sides of an argument. So it’s important to read over them carefully and put them in the perspective of your argument.
If there’s information that goes against your main points, don’t ignore it. Instead, acknowledge it. Then show how your argument is stronger.
If this all seems a little too theoretical, don’t worry—it’ll all get sorted out. I have a concrete example that takes a page from the Slytherins’ book (yes, of Harry Potter fame) and uses cunning resourcefulness when analyzing sources.
Great and Not-So-Great Topics for Your Synthesis Essay
A great topic for a synthesis essay is one that encourages you to choose a position on a debatable topic. Synthesis topics should not be something that’s general knowledge, such as whether vegetables are good for you. Most everyone would agree that vegetables are healthy, and there are many sources to support that.
Bad synthesis topics can come in a variety of forms. Sometimes, the topic won’t be clear enough. In these situations, the topic is too broad to allow for you to form a proper argument. Here are a few example bad synthesis essay topics:
Synthesis on gender
Write about education
Form an argument about obesity
Other not-so-great examples are topics that clearly have only one correct side of the argument. What you need is a topic that has several sources that can support more than one position.
Now that you know what a bad topic looks like, it’s time to talk about what a good topic looks like.
Many great synthesis essay topics are concentrated around social issues. There’s a lot of gray area and general debate on those issues—which is what makes them great topics for your synthesis. Here are a few topics you could write about:
Do video games promote violence?
Is the death penalty an effective way to deter crime?
Should young children be allowed to have cell phones?
Do children benefit more from homeschooling or public school?
The list of good topics goes on and on. When looking at your topic, be sure to present a strong opinion for one side or the other. Straddling the fence makes your synthesis essay look much weaker.
Now that you have an idea of what kinds of topics you can expect to see, let’s get down to how to actually write your synthesis essay. To make this a little more interesting, I’m going to pick the following example topic:
Are Slytherin House members more evil than members of other houses?
Steps to Writing an Impressive Synthesis Essay
As with any good essay, organization is critical. With these five simple steps, writing a surprisingly good synthesis essay is surprisingly easy.
Step 1: Read your sources.
Even before you decide on your position, be sure to thoroughly read your sources. Look for common information among them, and start making connections in your mind as you read.
For the purposes of my Slytherin synthesis example, let’s say I have four different sources.
- Source A is a data table that lists the houses of all members of the Death Eaters.
- Source B is a complete history of the Slytherin House, including the life and views of Salazar Slytherin.
- Source C is a document containing the names of students who were sorted into a different house than what the Sorting Hat had originally assigned to them.
- Source D is a history of the Battle of Hogwarts.
Step 2: Decide what your position is.
After you work through your sources, decide what position you are going to take. You don’t actually have to believe your position—what’s more important is being able to support your argument as effectively as possible.
Also, remember that once you pick a position, stick with it. You want your argument and your synthesis to be as strong as possible. Sticking to your position is the best way to achieve that.
Back to our example … after reading through my documents, I decide that the students and alumni of the Slytherin House are not more evil than students in the other houses.
Step 3: Write an awesome thesis statement.
Once you’ve decided on a position, you need to express it in your thesis statement. This is critical since you will be backing up your thesis statement throughout your synthesis essay.
In my example, my thesis statement would read something like this:
Students and alumni from Slytherin are not more evil than students in the other houses because they fill the whole spectrum of morality, evil wizards are found in all houses, and their house traits of cunning, resourcefulness, and ambition do not equate to an evil nature.
Step 4: Draft a killer outline.
Now that you have your argument down in words, you need to figure out how you want to organize and support that argument. A great way to do this is to create an outline.
When you write your outline, write your thesis statement at the top. Then, list each of your sub-arguments. Under each sub-argument, list your support. Part of my outline would look like this:
Thesis statement: Students and alumni from Slytherin are not more evil than students in the other houses because they fill the whole spectrum of morality, evil wizards are found in all houses, and their house traits of cunning, resourcefulness, and ambition do not equate to an evil nature.
I. Evil wizards are found in all houses.
A. Source A: Examples of Death Eaters from other houses
B. Source D: Examples of what Death Eaters from other houses did at the Battle of Hogwarts
In my outline, I used my sources as the second level of my outline to give the names of the sources and, from each, concrete evidence of how evil non-Slytherin wizards can be.
This is only an example of one paragraph in my outline. You’ll want to do this for each paragraph/sub-argument you plan on writing.
Step 5: Use your sources wisely.
When thinking about how to use your sources as support for your argument, you should avoid a couple mistakes—and do a couple of things instead.
Don’t summarize the sources. For example, this would be summarizing your source: “Source A indicates which houses the Death Eaters belong to. It shows that evil wizards come from all houses.”
Do analyze the sources. Instead, write something like this: “Although many Death Eaters are from Slytherin, there are still a large number of dark wizards, such as Quirinus Quirrell and Peter Pettigrew, from other houses (Source A).”
Don’t structure your paragraphs around your sources. Using one source per paragraph may seem like the most logical way to get things done (especially if you’re only using three or four sources). But that runs the risk of summarizing instead of drawing relationships between the sources.
Do structure your paragraphs around your arguments. Formulate various points of your argument. Use two or more sources per paragraph to support those arguments.
Step 6: Get to writing.
Once you have a comprehensive outline, all you have to do is fill in the information and make it sound pretty. You’ve done all the hard work already. The writing process should just be about clearly expressing your ideas. As you write, always keep your thesis statement in mind, so your synthesis essay has a clear sense of direction.
Now that you know what a synthesis essay is and have a pretty good idea how to write one, it doesn’t seem so intimidating anymore, does it?
If your synthesis essay still isn’t coming together quite as well as you had hoped, you can trust the Kibin editors to make the edits and suggestions that will push it to greatness.
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1. Polymers: From Petrol-Based to Biobased and Beyond
Polymers are one of the most important materials that are being exploited and developed by mankind, which play an essential and ubiquitous role in our modern life. They are large molecules or macromolecules that are composed of many small molecular fragments known as repeating units. They are in widespread use as plastics, rubbers, fibers, coatings, adhesives, foams and specialty polymers .
According to their origin, polymers can be classified as natural polymers or synthetic polymers. Natural polymers occur in nature via in vivo reactions, where biocatalysts, normally enzymes, are inevitably involved. Natural polymers can be found in all living organisms: plants, animals and human beings. Examples of natural polymers include lignocellulose, starch, protein, DNA, RNA and polyhydroxyalkanoates (PHAs), just to name a few. Normally, the structures of natural polymers are well-defined, with some exceptions like lignocellulose.
Synthetic polymers are commonly produced via polymerization of petrol-based chemicals having simple structures. Chemical catalysts, especially metal catalysts, are normally used in the preparation of synthetic polymers. Because of the booming of petrochemical industry and the concomitant availability of cheap petroleum oils, as well as the well establishment and advancement of polymerization techniques, numerous synthetic polymers have been developed, for example, phenol-formaldehyde resins, polyolefins, polyvinyl chloride, polystyrene, polyesters and polyamides, and so on. Synthetic polymers which include the large group known as plastics, became prominent since the early 20th century; and plastics are widely used as bottles, bags, boxes, textile fibers, films, and so on.
Currently, there is a huge demand for polymers. The global production of plastics increased from 225 million tons in 2004 to 311 million tons in 2014 (Scheme 1) ; and the global polymer production is expected to reach 400 million tons in 2020 . This huge polymer consumption leads to a massive demand for fossil resources for the polymer industry, which however brings some severe problems. On the one hand, fossil resources are depleting resources with limited storage; and their formation requires millions of years. There is a great concern that fossil resources will be exhausted within several hundred years. On the other hand, hazardous waste and emissions are generated along with the consumption of fossil resources, which induce severe environmental problems such as global warming and pollutions like smog and haze which are breaking out frequently, for instance in China nowadays. Driven by the growing environmental concerns, it is necessary and appealing to develop sustainable polymers for reducing the current dependence on fossil resources and decreasing the production of pollutants. As a matter of fact, laws have been approved by the European Union to reduce the usage of environmentally abusive materials, and to trigger more efforts to find eco-friendly materials based on renewable resources [4,5].
Biobased polymers are pointed out to be the most promising alternatives [5,6,7,8,9,10,11,12,13,14,15,16], which are defined as “sustainable materials for which at least a portion of the polymer consists of materials that are produced from renewable raw materials” . Generally speaking, biobased polymers can be produced via three routes [8,11]: (1) pristine natural polymers, or chemical or physical modifications of natural polymers; (2) manufactured biobased polymers from a mixture of biobased molecules with similar functionalities that are converted from biomass feedstocks; and (3) synthesis of biobased polymers via polymerization of biobased monomers with tailored chemical structures.
Some natural polymers such as natural rubber, cotton, starch and PHAs, are useful materials; however, they are limited in variety, and their properties and applications are also limited as they are determined by their chemical structure. Considering the rich abundance of biomass feedstocks in nature, it is of great interest to produce biobased polymeric materials by chemical or physical modifications of natural polymers, or from biobased molecules that are converted from biomass feedstocks. Actually human beings already used the former approach long time ago during the 1800s. Many commercially important polymers are prepared via this approach, for example, vulcanized natural rubber, gun cotton (nitrocellulose), cellulose esters and cellulose ethers. However, chemical and physical modifications of natural polymers are often subject to the poor solubility and process difficulty of natural polymers, as well as, unwanted impurities within the network of natural polymers which are hard to remove. On the other hand, conversion of biomass feedstocks to end-products is a promising pathway for the production of high tonnage consumer polymeric products such as paper, paints, resins and foams . For instance, oleochemicals can be converted from vegetable oils and fats, which are biobased building blocks for the production of thermoset resins and polyurethanes. However, the obtained biobased polymeric materials often possess diverse chemical structures; and it is nearly impossible to produce biobased polymers with identical structures as the petrol-based counterparts, due to the use of biomolecule mixtures. Besides, some unwanted structures or impurities might be inherited from the biomolecule mixtures, which might greatly influence the properties and applications of the final polymeric materials.
Utilization of biobased monomers with tailored structures in polymer synthesis is the most promising approach towards biobased polymers, which can result in not only sustainable alternatives to petrol-based counterparts with similar or identical structures, but also in novel green polymers that cannot be produced from petrol-based monomers [5,8,9,14,15,16]. However, this is also the most expensive approach of all three as aforementioned.
Benefiting from solar energy, numerous biobased monomers can be produced from yearly-based biomass feedstocks via biocatalytic or chemo-catalytic processes, which provide a great opportunity to access diverse biobased polymers [5,7,8,9,10,11,14,15,16,18,19,20,21,22,23,24,25,26,27]. Meanwhile, more and more biobased monomers are already or will become commercially available in the market due to the fast development of biotechnologies and their price will be competitive with that of the petrol-based chemicals [26,28,29,30,31,32,33,34].
Enzymatic polymerization is an emerging alternative approach for the production of polymeric materials, which can compete against conventional chemical synthesis and physical modification techniques [35,36,37,38,39,40,41,42,43,44]. Enzymatic polymerization also provides a great opportunity for accessing novel macromolecules that are not accessible via conventional approaches. Moreover, with mild synthetic conditions and renewable non-toxic enzyme catalysts, enzymatic polymerization is considered as an effective way to reduce the dependence of fossil resources and to address the high material consumption and pollution problems in the polymer industry.
At present, petrol-based monomers are still predominately used in enzymatic polymerizations. By combining biobased monomers and enzymatic polymerizations in polymer synthesis, not only the research field of enzymatic polymerization could be greatly accelerated but also the utilization of renewable resources will be promoted. This will provide an essential contribution for achieving sustainability for the polymer industry, which will eventually play an important role for realizing and maintaining a sustainable society.
Polyesters are polymers in which the monomer units are linked together by ester groups. Examples of polyesters include some naturally occurring polyesters like cutin, shellac, and poly (hydroxybutyrate) (PHB), and many synthetic polyesters such as poly(butylene succinate) (PBS), poly(lactic acid) (PLA), poly(ethylene terephthalate) (PET), polybutylene terephthalate (PBT) and poly(4-hydroxybenzoate-co-6-hydroxynaphthalene-2-carboxylic acid) (Vectran®, Kuraray, Chiyoda-ku, Tokyo, Japan). According to the chemical composition of the main chain, polyesters can be classified as aliphatic, semi-aromatic and aromatic polyesters (Scheme 2).
Most known aliphatic polyesters could be produced as biobased polymers [45,46], as the majority of their starting monomers can be produced from biomass feedstocks. Aliphatic polyesters are also (bio)degradable materials which can be recycled, disposed, composted or incinerated with a low environmental impact [46,47]. Aliphatic polyesters are widely used as thermoplastics and thermoset resins, with many commodity and specialty applications. Among them, PLA is the most well-known aliphatic polyester, which can be used as fibers, food packaging materials and durable goods, with a global demand of around 360 kilo tons in 2013 . PBS is another important commodity polyester which can be applied as packaging films and disposable cutlery, with a global market of around 10–15 kilo tons per year . In addition, aliphatic polyesters have found potential applications in biomedical and pharmaceutical fields such as in sutures, bone screws, tissue engineering scaffolds, and drug delivery systems, due to their biodegradability, biocompatibility and probable bioresorbability [46,50,51,52].
Compared to aliphatic polyesters, semi-aromatic polyesters generally possess better thermal and mechanical properties, which can be used as commodity plastics and thermal engineering plastics. Examples of semi-aromatic polyesters are poly(trimethylene terephthalate) (PTT), PET, PBT, and poly(ethylene naphthalate) (PEN). Among them, PET is the most commonly used semi-aromatic polyester. It is the fourth-most-produced plastic , with a global supply of more than 19.8 million tons in 2012 . PET has been widely used as beverage bottles, food containers, fibers and fabrics, packing films, photographic and recording tapes, engineering resins, and so on. It should be noted that PET is commonly referred by its common name, polyester, in textile and fiber applications; whereas the acronym “PET” or “PET resin” is used when applied as bottles, containers and packaging materials.
Aromatic polyesters are high performance thermoplastics, with high thermal stability and chemical resistance, and excellent mechanical properties. Aromatic polyesters have found many applications in the mechanical, chemical, electronic, aviation and automobile industries . However, aromatic polyesters generally possess a poor solubility even in aggressive solvents and are difficult to process, caused by their extremely rigid structures . Examples of aromatic polyesters are poly(4-hydroxybenzoate-co-6-hydroxynaphthalene-2-carboxylate) (Vectra®, Celanese, Irving, TX, USA; Vectran®, Kuraray, Chiyoda-ku, Tokyo, Japan), poly(4-hydroxybenzoate-co-4,4′-biphenylene terephthalate) (Xydar®, Solvay, Brussels, Belgium; Ekonol®, Saint-Gobain, Courbevoie, France) and poly(6-hydroxynaphthalene-2-carboxylate-co-4-hydroxybenzoate-co-4,4′-biphenylene terephthalate).
Besides, aromatic polyesters and some semi-aromatic copolymers such as poly(2-chlorohydroquinone terephalate-co-l,4-cyclohexylenedimethylene terephthalate) and poly(p-hydroxybenzoate-co-ethylene terephthalate) are liquid crystalline materials in which both liquid crystalline and polymer properties are combined. These liquid crystalline polyesters are generally characterized by a rod-like molecular structure, rigidness of the long axis, and strong dipoles . Aromatic polyesters are good candidates for thermotropic main-chain polymers due to the highly rich aromatic (mesogenic) fragments, and the low inter-chain forces because of the relatively low energy of association of the ester groups.
Generally speaking, polyesters can be produced via two methods: (1) step-growth polycondensation of diols and diacid/diesters, or hydroxyacids/hydroxyesters; and (2) ring-opening polymerization of cyclic monomers (lactones, cyclic diesters and cyclic ketene acetals) and cyclic oligomers. Both of these two methods have some merits and also suffer from some drawbacks. On the one hand, the building blocks for step-growth polycondensation are generally easily obtained at a relatively cheap price. However, elevated reaction temperatures (150–280 °C), long reaction times, high vacuum condition, heavy metal catalysts and a precise stoichiometric balance between monomers are normally required for polycondensation. In addition, side-reactions and volatilization of monomers may occur at elevated temperatures or under high vacuum [50,57]. On the other hand, removal of by-products is not required by ring-opening polymerization and, therefore, high molecular weight products can be obtained under relatively mild conditions in a matter of minutes. Besides, side reactions can be greatly suppressed during ring-opening polymerization. However, extra synthesis steps and heavy metal catalysts are often required for the preparation of the starting materials, cyclic monomers and cyclic oligomers.
Moreover, polyesters can be also synthesized by other methods such as polyaddition of diepoxides to diacids , and acyclic diene metathesis (ADMET) polymerization of diene monomers containing ester bonds in the main chain .
At present, some biobased polyesters are already commercially available, including fully biobased PLA, PHAs, and poly(ethylene furanoate) (PEF), partially biobased PBS, PET, PTT and poly(butylene adipate-co-terephthalate) (PBAT), and so on (Table 1) [34,49,60,61,62,63,64,65,66,67,68]. However, polymers including polyesters, polyamides and other types, are still mainly derived from petroleum oils. The production capacity of biobased polymers represented only a 2% share of the total polymer production in 2013 and will increase to 4% by 2020 .
Polyamides are polymers in which the monomeric units are linked together by amide bonds. Examples of polyamides include naturally occurring polyamides like proteins, and synthetic polyamides such as polycaprolactam (nylon 6 or PA 6), poly(hexamethylene adipamide) (nylon 6,6 or PA 6,6), poly(hexamethylene terephathamide) (PA 6,T), and poly(p-phenylene terephathamide) (PPTA, Kevlar®, DuPont, Wilmington, DE, USA). Similar to polyesters, polyamides can be classified to three types: aliphatic, semi-aromatic and aromatic polyamides, depending on the chemical composition of the main chain (Scheme 2).
Aliphatic polyamides, commercially known as nylons or nylon fibers, are highly valued semi-crystalline thermoplastics that are widely used as synthetic fibers, construction materials, food packing materials, engineering resins, and so on . Currently, a variety of aliphatic polyamides are commercially manufactured, including nylon 6 (PA 6), nylon 10 (PA 10), nylon 11 (PA11) and nylon 12 (PA 12), and nylon 4,6 (PA 4,6), nylon 6,6 (PA 6,6), nylon 6,10 (PA 6,10) and nylon 6,12 (PA 6,12). Among them, nylon 6 is the largest produced aliphatic polyamide by far, with a global production of 4.2 million tons in 2010; and nylon 6,6 ranked the second largest aliphatic polyamide in the market, with a global production of 2.1 million tons. Actually, nylon 6,6 is the first example of aliphatic polyamides, which was firstly produced in the laboratory by Carothers and Hill at DuPont in 1930. After that, this polyamide was prepared by DuPont as nylon 6,6 fiber on 28 February 1935, and then produced at full-scale in July 1935. Regarding nylon 6, it was firstly developed by Schlack at IG Farbenindustrie in 1938, for the purpose of reproducing the properties of nylon 6,6 without violating the patents [70,71]. At present, 66% of nylon 6 production is used as fibers, 30% is applied as engineering thermoplastics, and the rest 10% is consumed as films. For nylon 6,6, 55% of the current production is used as fibers, and the remainder is applied as engineering thermoplastics. Other nylons like nylon 4,10, nylon 6,12, nylon 10,10, nylon 11 and nylon 12 are commonly used as high performance materials .
Semi-aromatic polyamides consist of both aliphatic and aromatic fragments in the polymer main chain. Especially, polyphthalamides (PPAs), a type of semi-aromatic polyamides, are defined by ASTM D5336 as “polyamides in which at least 55 mol % of the carboxylic acid portion of the repeating unit in the polymer chain is comprised by a combination of terephthalic acid (TPA) and isophthalic acid (IPA)” . Compared to aliphatic polyamides, semi-aromatic polyamides are much stiffer, rendering the polyamides with higher mechanical strength and better thermal resistance. In addition, semi-aromatic polyamides possess many other merits such as high heat chemical/abrasion/corrosion resistance, good dimensional stability, superior processing characteristics and direct bonding to many elastomers. Semi-aromatic polyamides can be used as thermal engineering materials and high performance materials, which have found various applications in many areas, for example, in marine, automotive industry, oil industry, electronics, machinery, domestic appliances, medical devices, personal care, and so on. Examples of semi-aromatic polyamides are PA 6,T, poly(nonamethylene terephthalamide) (PA 9,T), and poly(decamethylene terephthalamide) (PA 10,T). They are commercially produced by many companies such as DuPont (Zytel®HTN, PA 6,T), Solvay (Amodel®, PA 6,T), EMS-GRIVORY (Grilamid®HT, PA 6,T), Mitsui (ARLEN®, PA 6,T/6,6), Kuraray (Genesta®, PA 9,T), and Evonik (VESTAMID®HTplus, PA 6,T/X or PA 10,T/X) [72,74].