Talk:End group

Mcark Peer Review
So I’ve gone through and made comments on the article, then at the end I have a summary paragraph. Had a comment about correct number of sections, but I was wrong, there are four.

For your introduction, I’m not sure if “functionalities” or “constitutional units” are relatable to a general audience. Maybe "chemical functional groups" or even "chemical groups?" Also I think that describing end groups as an “aspect” of polymer chemistry might be a bit unclear. The study of end groups might be an aspect of polymer chemistry, but I feel like "aspect" might be an inappropriate noun. I also think you could edit some of your sentence structure to make your topic more clear. For example, instead of, “In polymer synthesis, like condensation polymerization and free-radical types of polymerization, end-groups are commonly used,” try “End-groups are commonly used in different methods of polymer synthesis such as condensation and free-radical polymerization.” I’m not sure if you need to refer to your figure in the introduction. I think it's a good, clarifying figure, but I think it stands well alone. Also I would change, “end groups are used most commonly for analysis via NMR” to “end groups are used frequently for analysis via NMR” unless you can provide a citation that NMR is the most common analytical method. I think the general flow of “Here’s what end groups are. They are important for synthesis. They are also important for characterization” is a good general structure.

For your first section, I might mention something about synthesis in the title, as that’s what the section seems to be about. Also, your first sentence of the section seems to talk about applications more than synthesis or polymerization. Also it would be, “(free radical, condensation, etc.)” No “or.” I think that step-growth polymerization would be a class of polymerization, and then condensation would be a type within that class. Also aren’t there many monomeric condensation polymerizations? If not, provide a citation for stating that condensation polymerizations usually involve two or more monomers. Good examples here and interesting discussion about controlling end groups, but maybe in the figure, use “excess” instead of “more.”

The word “used” in your free radical polymerization section seems to imply that termination method and chain transfer agents are intentional, like a chemist intentionally uses chain transfer to solvent, as opposed to the termination pathway being a natural occurrence in polymer synthesis. Is this how you want it to come off? I think your content in the free radical polymerization section about how end groups are related to initiators is good. Maybe list a few termination methods and the end groups they result in?

Try to align your “Analysis of polymers using end groups” section so that it doesn’t start in the middle of your two figures. For your first sentence, try “developed for their identification” instead of, “the identification of the groups.” Make sure to link to the articles for the analytical techniques every time. Also “detailed” not “details.” I think that “the beauty of NMR (add link?)” might be a bit tonally inappropriate for an encyclopedia article. I think your NMR section might be a bit excessive. I feel like you maybe do not need the calculation in there. Maybe just say, “The relative rates of proton abundance can be used to calculate the degree of polymerization” or something like that. I think your figure of the structure with its circled protons is great, but I don’t know if you need the table. Also, figure out how to do a subscript for the Xn stuff. Also I would double check on whether to say, “calculate the Xn” versus “calculate Xn.” I’m not sure which is correct.

In the first sentence of your mass spec section, try “molecular weight, structure, degree of polymerization, etc.” Using active voice versus passive voice can make some of your sentences more clear, for example, “Although chemists utilize many kinds of MS, the two that are used most typically are…” Your discussion of disadvantages is a bit unclear. What does “simpler data” mean? What does “hard” or “soft ionization” mean? Go more into depth in your Vibrational Spectroscopy section. What kind of data does it produce? What is it helpful for?

I’m not sure what you mean by End Group Removal. Maybe explain what the section is about more generally before jumping into an example. I feel like the section may be a bit too specific to RAFT polymerization. While your explanation of this method is great and detailed, maybe add some different type of end group removal methods and why end group removal is important.

Overall I think you present interesting information, but maybe try thinking about what information you want to prioritize. Most of the sections in Polymerization and Characterization are good, but there are some more problematic ones (see above comments). Also work on making your writing clearer and more concise. I think reading aloud would really help. As far as linking terms go, I think you're good, but you may want to consider whether or not to link to a page every time you use a term. For the most part your figures are good, but I think that you could consider the sizing of them. For example, does the polystyrene figure have to be so big relative to the RAFT polymerization mechanism figure, which is very difficult to make out without enlarging? Also a few of your figures might be unnecessary. I would maybe think about outlining your article and condensing what you want to say in each section into bullet points. Start with more general ideas and then fit your examples in to support those concepts. Your sources look good and you’ve included non-journal sources, but I feel like a textbook source might really help you develop some of the more general, "bigger" facts about end groups. Good job! Mcark (talk) 02:53, 28 February 2014 (UTC)

Instructor Comments
I agree with the 2nd reviewer that some additions are warranted - namely a discussion of the "good" things that emanate from having specific end-groups. For example, the ability to bind polymers to surfaces (Polymer-S to Au) or the ability to graft/initiate an additional polymer, etc. End-groups are often there for a reason, and your page does not really comment on this, but rather focuses on how they can be used in characterization, which is a minor detail compared to the power of having specific end-groups on the polymer chains. UMChemProfessor (talk) 03:36, 3 March 2014 (UTC)

Charco0917 Review
Overall I think that this page is a big improvement over the previous page and provides a lot ore detail. The content of the introduction is easy to understand for non-experts and gives a good understanding of what an end group is. Also, the content of the page is unique in that it does not duplicate material already present on wikipedia. I did find that the second and third sentence of the introduction could be combined into one sentence. "In polymer synthesis, like condensation polymerization and free-radical types of polymerization, end-groups are commonly used. End groups are used most commonly for analysis via nuclear magnetic resonance (NMR) where the end group can be used to determine the average length of the polymer." I think that the end groups in polymerization section could be expanded upon by adding a "End groups in synthesis" section which could go more in depth into the on the topic, already mentioned, of adding excess monomer to control the end group of the resulting polymer but focus on the synthetic applications of this concept. In addition there are post-polymerization functionalizations that can be performed by incorporating various end groups or endcapping a polymer. For example in living polymerizations quenching the active species with different reagents or adding monomer with a specific end group can allow the resulting polmer to be modified post-polymerization (McCollough has references with polythiophene for this). While the highlighted examples are appropriate I believe they are mostly from class notes so a reference may be required or alternative example. In the NMR section the first sentence using the wording "The beauty of NMR" seems like inappropriate wording to use in wikipedia. Also, in the NMR section your article states that the biggest drawback for NMR functional group analysis is that the polymer must be soluble in organic solvents but i do not think this state ment should be modified with "organic solvents" because D2O could be used. In addition, there are other drawbacks that restrict the analysis to low MW polymers (signal of end group gets lost due to the signals from the repeat unit). You did a good job internally linking most of the concepts to other wikipedia pages, however there could e a link for polystyrene.

Th figures of the page are helpful in understanding the text and for the most part provide a good explanation. Mainly the figures need to be re-sized (some are illegibly small) and possibly re-positioned (looking up the "wiki-cheat sheet" will provide you the syntax needed). It is difficult to compare because not all are on the same scale but the sizes of the atoms (non-carbon atoms) in the chemdraw figures may have different sizes. Be sure that the font size in your chemdraw for heteroatoms is consistent between figures. The RAFT figure was somewhat confusing, I think more description in the figure (i.e. which step and what was the active species quenched with ?) may help the readers understanding.

I think adding more free online references to your sources (even if not used as your primary reference) would be beneficial to the wikipedia readers who do not have journal access. The examples highlighted throughout the page seem to be from class notes which is fine but I think there should be a reference so the readers may verify what you are explaining to them.

Overall, the page is an improvement over the previous wikipedia page and I think that you go into the end group techniques used to characterize polymers with good detail. However, I think that the page could further be expanded to highlight the synthetic applications of end groups in both condensation and chain growth polymerization (i.e. endcapping, grafting, Co-block polymers). The figures were clear and explained the text well but they need to be reformatted to improve the size and position on the wiki-page. The references given seem to focus around journal articles that may ot be accessible to all wikipedia users, I think adding free online sources would be benificial. The sandbox provides a good starting point for someone looking for end group analysis and provides detailed examples.

Charco0917 (talk) 16:12, 28 February 2014 (UTC)

Suggestions from ChemLibrarian
A few more suggestions here.


 * Some of your figures need adjusting locations and sizes. See Picture tutorial for tips on doing that.
 * I see you posted your tables as figures. That's not encouraged since the texts in there are not machines readable. And the resolution is low. Formatting tables in Wikipedia is not hard. Please see Help:Table for details on how to do it.

ChemLibrarian (talk) 16:51, 3 March 2014 (UTC)

Comments to Mcark Review
Thank you for all of you comments and suggestions on how to improve our page. We have fixed the various grammatical errors and sentence structure errors that you had noted in your review. We have altered first section title to reflect that it is about the synthesis of polymer end groups, as well as adding a short snip it about step-growth polymerization. The figure in the first section has also been changed to use the term excess instead of more. For the radical polymerization, we did not include a list of termination pathways since that is already covered in the radical polymerization page on Wikipedia. Your comments on the characterization section were helpful, especially with the use of the active voice. Also we chose to not go too in depth into the various techniques since there are Wikipages devoted to them, but we have linked them to those pages.

Comments to Charco0917 Review
Thank you for your thorough review of our Wikipedia site. Your suggestions pointed out ways in which we can fix errors and optimize our page to make it more effective. We fixed grammatical errors (2nd and 3rd sentence) as you suggested. We decided to add sections on graft copolymers and surface modifications to describe the ways in which end groups can be used to make new polymer architectures. Our highlighted examples are derived from a number of sources and are mainly meant to be general or simple for the reader to understand; we added some new figures to go with new information we added and altered others to make them more clear. Although D2O can be used to do NMR we felt that it is not a commonly used NMR solvent in practice and many polymers are insoluble in water. You pointed out that other drawbacks of NMR include the fact that it is limited to low molecular weight polymers; this was pointed out in our NMR spectroscopy section. Per your suggestion, we repositioned and resized figures to optimize the flow of the page; we feel that it looks much better now. We left the RAFT figure, because we thought that it was effective in explaining the general mechanism of RAFT polymerization, which we have seen in various sources. We did however try to better point out the points at which we are referring to the figure. Thank you for all of your great suggestions, we think that the page is much better now that we have made the corrections.

Comments to UMChemProfessor Review
Thank you for you comments and suggestion on some additions that we could make to improve our page. We have added sections on both surface modification using RAFT and end groups in graft polymers to highlight the utility of end groups besides in just the characterization of the polymers. We have also added an image to illustrate the surface modification of gold with the addition of a thiol end group.

Comments to ChemLibrarian Review
Thank you for you comments and suggestions on fixing the images on our page. We have resized many of the images to a more proper size and have removed the one table that just didn't really fit. We did however leave the table listing the various initiator and the radicals that are formed upon activation.

CrystalLettuce (talk) 10:50, 13 March 2014 (UTC) Schrodingerscat101 (talk) 10:50, 13 March 2014 (UTC) — Preceding unsigned comment added by CrystalLettuce (talk • contribs) Schrodingerscat101 (talk) 03:05, 14 March 2014 (UTC)