User:AlphaBravo12/sandbox

Article Evaluation (Polymer)
The mechanical properties section only addressed two types of properties. It didn't mention toughness, wear resistance, or many other mechanical properties that could be pertinent to polymers.
 * The article seems very relevant, nothing that I read made me question why it was in the article.
 * Plasma polymerization could have been addressed in slightly more detail rather than say it did not fit neatly into the other two categories of chain growth. It was a little distracting not to just be told why, it made me want to click the wiki link and switch off the article I was on to read about it.
 * The section on morphology seemed a little lacking. For one thing, lamellae were not described in that section even though that is the name given to ordered regions.
 * Lastly, it was interesting that there wasn't even a minor discussion on chain reptation in the morphology or mixing section. It's widely modeled phenomenon that is really relevant to polymer interaction and mechanical behavior.
 * Overall, it was a thorough article, I think some sentence structures could have been bettered to make the reading a little more clear.
 * The article did appear neutral. I didn't sense any bias towards better materials, methods, or applications.
 * There weren't really any viewpoints that were over- or underrepresented. There was subject matter that could have more detail added but not really viewpoints.
 * The links that I tried do work. There were a few citations such as, "McCrum, p. 30" that were not in the bibliography and gave no additional information. Those were not possible to judge whether the information supported what was stated. Otherwise, what I found seemed to back up the facts listed in the article.
 * It would seem that quite a few references are missing. The sections on degradation and product failure are lacking in references having one between to the two sections that I could see.
 * I couldn't really tell if sources were biased or not. It didn't seem that way. Journal articles can definitely have bias but it seems that they were not used to promote different polymers over one another or make claims about the benefits of one method vs. another.
 * Talk Page
 * The talk page seems to think the article was written at too high of a level, which I can agree with. The person who wrote that did not seem to abide by the, "don't be rude" rule. They were a little demeaning to the person writing it.
 * Some people also pointed out the problems with the article that I did, i.e. a lack of mechanical properties and references later on in the article.
 * The article is rated a, "level-4 vital article". It does not seem to be a part of any wiki projects.
 * I think that this article is actually below the level that we are talking about it in class. The article definitely resonates with things that we have gone over, but we have been talking about things in much more depth. In class, we have also been getting more of the history of the polymer process.

AlphaBravo12 (talk) 13:38, 4 April 2019 (UTC)

Article Selection
Polymer Blend


 * This articles content is relevant to the topic. A discussion of the methods of blending polymers is given while a few examples are listed.
 * The article did seem neutrally written.
 * Each claim did not have a citation, notably the history section had no citations.
 * It appeared that the sources cited were reliable.

Polyethylene Wax


 * The topic is not well covered, it only has two sentences describing it. The sentences do appear relevant though.
 * It is a very neutral tone.
 * Each claim had a citation. The citations seemed reliable.

Polyethylene Adipate


 * The topic has little information on it but what is there is relevant. Close paraphrasing may have been used in the article.
 * The tone of the article is neutral.
 * Each claim does not have a citation. The citations that are present do seem reliable.

AlphaBravo12 (talk) 15:08, 9 April 2019 (UTC)

Outline for Wikipedia Article
Original from Wikipedia:

Polyethylene adipate (or PEA), is an aliphatic polyester formed from polyethylene glycol and adipic acid. Its CAS Number 24938-37-2 and its linear formula is [OCH2CH2OCO(CH2)4CO]n. It forms monoclinic crystals, mp 55C,[1] and the amorphous material has a low Tg at -70C. However its practical use is mostly as a pre-polymer of polyurethane. It is often blended with other polyesters to form the soft segments. A strain of Penicillium 14-3 can degrade it. Lipases from R. arrizus, R. delemar, Achromobacter sp. and Candida cylindracea; as well as an esterase from hog liver also degraded PEA.[2]

This article has a lot of close plagiarism, plagiarism, and poor grammar.

Outline for Improved Article (Modeled on the Polyethylene Wikipedia article):

1.     Intro

a.     Background on PEA, summarize article

2.     Properties

a.     Intro - nice selection of basic properties (melting point and etc.) from: https://www.chemicalbook.com/ProductChemicalPropertiesCB9291025_EN.htm (not on bibliography)

https://www.sciencedirect.com/science/article/pii/0013468684870255

https://www.sciencedirect.com/science/article/pii/S0014305700000574

This will allow for a well rounded discussion on Tg and Tm as well as other traits of the polymer using several sources to avoid close plagiarism. This section can discuss why aliphatic copolyesters are used and what their benefits are.

b.     Mechanical properties

This section will address the low mechanical properties of PEA. Its main benefit is as a plasticizer so it does not have very high mechanical strength.

https://www.sciencedirect.com/science/article/pii/S0014305700000574

c.      Crystallization

PEA crystallizes as spherulites and can form double banded rings. This is mentioned in several sources and the crystallinity can affect biodegradability among other properties.

https://www.sciencedirect.com/science/article/pii/S0032386109010593

https://pubs.acs.org/doi/abs/10.1021/ie901356q

https://pubs.acs.org/doi/abs/10.1021/ie301968f

https://pubs.acs.org/doi/abs/10.1021/cg5002539

d.     Microstructure

The microstructure of PEA goes beyond just descriptions of the crystal patterns. One author compared it to the banding in butterfly wings or the skins of fruit.

https://pubs.acs.org/doi/10.1021/acs.macromol.8b00549

e.      Conductance

PEA has been used as a conductive polymer before with moderate success. It has interesting material properties under a current including that it can recrystallize.

https://www.sciencedirect.com/science/article/pii/0013468684870255

3.     Synthesis

a.     Polycondensation

Polycondensation is the usual route taken in order to synthesize PEA. The reaction is between dimethyl adipate and ethylene glycol.

https://www.sciencedirect.com/science/article/pii/S0014305707002832

b.     Ring-opening polymerization

Ring-opening polymerization can also be used to obtain PEA, it can be denoted ROP-PEA. This alternate method may be beneficial as it uses different initial chemicals to derive.

https://www.sciencedirect.com/science/article/pii/S0014305707002832

4.     Biodegradability

a.     Biodegradability

PEA can increase the ability for a copolymer blend to be hydrolyzed. This could be very useful in creating environmentally friendly plastics and alternative petrochemicals.

https://www.sciencedirect.com/science/article/pii/S0141391018302635

https://www.sciencedirect.com/science/article/pii/S0040603117303052

https://www.sciencedirect.com/science/article/pii/S0014305700000574

5.     Uses for PEA and Chemically Modified PEA

a.     Mending capabilities

Adding Diels-Alders bonds to the PEA backbone can enable it to mend. This is beneficial as self-mending polymers have industrial advantages.

https://www.sciencedirect.com/science/article/pii/S0141391010000522

b.     Aromatic side chains

One paper in particular looked at how PEA with an aromatic phenyl side chain was added. They included a discussion on mechanical properties, how chain alignment is affected, and how biodegradability changes with increasing side chain addition.

https://www.sciencedirect.com/science/article/pii/S0014305700000574

c.      Microcapsules for drug delivery

When PEA is combined with PBA it forms a porous microstructure that could be used for drug delivery.

https://pubs.rsc.org/en/Content/ArticleLanding/2015/SM/c4sm02489c#!divAbstract

d.     Plasticizer

PEA when combined with other polymers, like PLA, can cause the materials to become more plastic and less brittle.

https://www.sciencedirect.com/science/article/pii/S0040603117303052

Images:

Spherulite structure

While not directly specific to PEA, it would make a nice image and is from Wikipedia Commons.

Ring banding (drawn/reproduced/cartoon)

I will make a cartoon of the ring banding shown below from Meyer et al. (2010). A cartoon will suffice to show the patterning that PEA shows.

PEA structure

As far as I can tell, there is no copyright protection on chemical formulas. Therefore, I’ll be reproducing, with some alterations, the chemical structure from Sigma Aldrich for the Wikipedia page:

https://www.sigmaaldrich.com/catalog/product/aldrich/181919?lang=en&region=US

PEA synthesis

This will give a good background on how PEA is made and what it is made from. Again, as far as I can tell there is no copyright on chemical formulas or reactions. I will reproduce it to make it clearer and unique. This was from Pathavuth et al. (2007).

https://www.sciencedirect.com/science/article/pii/S0014305707002832

AlphaBravo12 (talk) 00:15, 25 April 2019 (UTC)

__________________________________________________________________________________

= Poly(ethylene adipate) = Poly(ethylene adipate) or PEA is an aliphatic polyester. It is most commonly synthesized from a polycondensation reaction bet ween polyethylene glycol and adipic acid. PEA has been studied as it is biodegradable through a variety of mechanisms and also fairly inexpensive compared to other polymers. Its lower molecular weight compared to many polymers aids in its biodegradability.

Polycondensation
Poly(ethylene adipate) can be synthesized through a variety of methods. First, it could be formed from the polycondensation of dimethyl adipate and ethylene glycol mixed in equal amounts and subjected to increasing temperatures (100°C, then 150°C, and finally 180°C) under nitrogen atmosphere. Methanol is released as a byproduct of this polycondensation reaction and must be distilled off. Second, a melt condensation of ethylene glycol and adipic acid could be carried out at 190-200°C under nitrogen atmosphere. Lastly, a two-step reaction between adipic acid and ethylene glycol can be carried out. A polyesterification reaction is carried out first followed by polycondensation in the presence of a catalyst. Both of these steps are carried out at 190°C or above. Many different catalysts can be used such as stannous chloride and tetraisopropyl orthotitanate. Generally, the PEA is then dissolved in a small amount of chloroform followed by precipitation out in methanol.

Ring-Opening Polymerization
An alternate and less frequently used method of synthesizing PEA is ring-opening polymerization. Cyclic oligo(ethylene adipate) can be mixed with di-n-butyltin in chloroform. This requires temperatures similar to melt condensation.

Properties
Poly(ethylene adipate) has a density of 1.183g/mL at 25°C and it is soluble in benzene and tetrahydrofuran. PEA has a glass transition temperature of -50°C. PEA can come in a high molecular weight or low molecular weight variety, i.e.10,000 or 1,000 Da. Further properties can be broken down into the following categories.

Mechanical Properties
In general, most aliphatic polyesters have poor mechanical properties and PEA is no exception. Little research has been done on the mechanical properties of pure PEA but one study found PEA to have a tensile modulus of 312.8 MPa, a tensile strength of 13.2 MPa, and an elongation at break of 362.1%. Alternate values that have been found are a tensile strength of ~10 MPa and a tensile modulus of ~240 MPa.

Chemical Properties
IR spectra for PEA show two peaks at 1715-1750cm-1, another at 1175-1250cm-1, and a last notable peak at 2950cm-1. These peaks can be easily determined to be from ester groups, COOC bonds, and CH bonds respectively.

Crystallization Properties
PEA has been shown to be able to form both ring-banded and Matlese-cross (or ring-less) type spherulites. Ring-banded spherulites most notably form when crystallization is carried out between 27°C and 34°C whereas Matlese-cross spherulites form outside of those temperatures. Regardless of the manner of banding, PEA polymer chains pack into a monoclinic crystal structure (some polymers may pack into multiple crystal structures but PEA does not). The length of the crystal edges are given as follows: a = 0.547nm, b = 0.724nm, and c = 1.55nm. The monoclinic angle, α, is equal to 113.5°. The bands formed by PEA have been said to resemble corrugation, much like a butterfly wing or or Pollia fruit skin.

Electrical Properties
Conductivity of films made of PEA mixed with salts was found to exceed that of PEO4.5LiCF3SO3 and of poly(ethylene succinate)/LiBF4 suggesting it could be a practical candidate for use in lithium ion batteries. Notably, PEA is used as a plasticizer and therefore amorphous flows occur at fairly low temperatures rendering it less plausible for use in electrical applications. Blends of PEA with polymers such as poly(vinyl acetate) showed improved mechanical properties at elevated temperatures.

Miscibility
PEA is miscible with a number of polymers including: poly(L-lactide) (PLLA), poly(butylene adipate) (PBA), poly(ethylene oxide), tannic acid (TA), and poly(butylene succinate) (PBS). PEA is not miscible with low density polyethylene (LDPE). Miscibility is determined by the presence of only a single glass transition temperature being present in a polymer mixture.

Biodegradability
Aliphatic copolyesters are well known for their biodegradability by lipases and esterases as well as some strains of bacteria. PEA in particular is well degraded by hog liver esterase, ''Rh. delemar, Rh. arrhizus, P. cepacia, R. oryzae, and Aspergillus sp. '' An important property in the speed of degradation is the crystallinity of the polymer. Neat PEA has been shown to have a slightly lower degradation rate than copolymers due to a loss in crystallinity. PEA/poly(ethylene furanoate) (PEF) copolymers at high PEA concentrations were shown to degrade within 30 days while neat PEA had not fully degraded, however, mixtures approaching 50/50 mol% hardly degrade at all in the presence of lipases. Copolymerizing styrene glycol with adipic acid and ethylene glycol can result in phenyl side chains being added to PEA. Adding phenyl side chains increases steric hindrance causing a decrease in the crystallinity in the PEA resulting in an increase in biodegradability but also a notable loss in mechanical properties.

Further work has shown that decreasing crystallinity is more important to degradation carried out in water than whether or not a polymer is hydrophobic or hydrophillic. PEA polymerized with 1,2-butanediol or 1,2-decanediol had an increased biodegradability rate over PBS copolymerized with the same side branches. Again, this was attributed to a greater loss in crystallinity as PEA was more affected by steric hindrance, even though it is more hydrophobic than PBS.

Poly(ethylene adipate) urethane combined with small amounts of ligin can aid in preventing degradation by acting as an antioxidant. Additionally, the mechanical properties of the PEA urethane increased by ligin addition. This is thought to be due to the rigid nature of ligin which aids in reinforcing soft polymers such as PEA urethane.

When PEA degrades, it has been shown that cyclic oligomers are the highest fraction of formed byproducts.

Ultrasonic degradation
Using toluene as a solvent, the efficacy of degrading PEA through ultrasonic sound waves was examined. Degradation of a polymer chain occurs due to cavitation of the liquid leading to scission of chemical chains. In the case of PEA, degradation was not observed due to ultrasonic sound waves. This was determined to be likely due to PEA not having a high enough molar mass to warrant degradation via these means. A low molecular weight has been indicated as being necessary for the biodegradation of polymers.

Plasticizer
Poly(ethylene adipate) can effectively be used as a plasticizer reducing the brittleness of other polymers. Adding PEA to PLLA was shown to reduce the brittleness of PLLA significantly more than poly(butylene adipate) (PBA), poly(hexamethylene adipate) (PHA), and poly(diethylene adipate) (PDEA) but reduced the mechanical strength. The elongation at break was increased approximately 65x over neat PLLA. The thermal stability of PLLA also showed a significant increase with an increasing concentration of PEA.

PEA has also been shown to increase the plasticity and flexibility of the terpolymer maleic anhydride-styrene-methyl metacrylate (MAStMMA). Observing the changes in thermal expansion coefficient allowed for the increasing in plasticity to be determined for this copolymer blend.

Mending capabilities
Self-healing polymers is an effective method of healing microcracks caused by an accumulation of stress. Diels-Alder (DA) bonds can be incorporated into a polymer allowing microcracks to occur preferentially along these weaker bonds. Furyl-telechelic poly(ethylene adipate) (PEAF2) and tris-maleimide (M3) can be combined through a DA reaction in order to bring about self-healing capabilities in PEAF2. PEAF2M3 was found to have some healing capabilities after 5 days at 60°C, although significant evidence of the original cut appeared and the original mechanical properties were not fully restored.

Microcapsules for drug delivery
PEA microbeads intended for drug delivery can be made through water/oil/water double emulsion methods. By blending PEA with Poly-ε-caprolactone, beads can be given membrane porosity. Microbeads were placed into a variety of solutions including a synthetic stomach acid, pancreatin, Hank's buffer, and newborn calf serum. The degradation of the microcapsules and therefore the release of the drug was the greatest in newborn calf serum, followed by pancreatin, then synthetic stomach acid, and lastly Hank's buffer. The enhanced degradation in newborn calf serum and pancreatin was attributed to the presence of enzyme activity and that simple ester hydrolysis was able to be carried out. Additionally, an increase in pH is correlated with higher degradation rates.

AlphaBravo12 (talk) 17:24, 30 April 2019 (UTC)