Polymerization - Science topic

I am trying to develop of a Sustain release drug (BCS class I). so that, I want to use a hydrogel forming agent which molecular weight out of range between 100,000 and 8,000,000. I am also wanting to avoid following hydrogel forming polymer group- Polyethylene oxide, hydroxypropyl, methylcellulose, hydroxypropyl cellulose and Carboxyvinyl polymer.

I am currently running thermal polymerizations of compounds that form free radicals at elevated temperatures (T>120 degrees C).  I want to attempt to polymerize at discrete temperatures between 120 and 200 degrees C.  

Can I use AIBN radical initiator at these elevated temperatures without risk of explosion (in the literature it seems that AIBN is typically used at temps ranging from 60-80 degrees C)?  

If not, is there another radical initiator I can use at temperatures this high??

Thanks!

I am fabricating a polymer by the bulk free-radical process. The monomers are very sensitive to the 60 degree centigrade. How can I have free radical polymerization by Azo initiators from 25 to 40 degree centigrade?

It seems this polymer exists widely and the lyases that are specific for it are relatively abundant in genomes of both fungi and bacteria. I have searched extensively in litterature but I may have missed something. Is it part the cellwalls or an eps with a purpose?

Best regards

-B

Hi,everyone！I want to ask that:After the AC containing the polymer chain is optimized, water molecules are added, and then molecular dynamics simulation is performed. How to see how much pressure is set to be reasonable for the AC containing water molecules and polymer chain?If the pressure is lower than the pressure used to balance the polymer chain unit cell, the structure of the polymer chain will change, and the density will decrease, etc.so I am confused, thank you all!

Dear Reader,

Recently, I have prepared a polymeric nanofiber using PVA polymer doped with some nanoparticles and I want to find out its microhardness. So, I was planning to do nanoindentation characterization. The nanofibers were fabricated by electrospinning method and it was obtained as a thin layer coated on a glass substrate, the thickness of the nanofibers was found to be in the ranges 31 nm to 120. As I am expecting meaningful results, what could be the appropriate load and loading rate to carried nanoindentation on the nanofiber?.

Thank you

Hi, I was wondering if anyone could help me here. I noticed that a pMMA plastic that I have is experiencing cloudy swirling patterns at its interface with an aqueous terpene solution. I was wondering if anyone could help me understand what is going on.

Based on what I know about terpenes, I don't think this is a chemical reaction. If it is a chemical reaction, I would think chain scission would be the most likely cause. However, I don't really see how this could be happening.

My other thought is that this is a solvent effect. The terpene is low MW, and with a backbone, I could see some solvent migrating into the polymer's amorphous structure. This would create areas with different refractive indexes and hence the cloudy appearance on the polymer. I think this is what is happening, but I can't find any research to back it up and wonder if anyone else has any ideas.

Thank you,

Is/are there some other factors than Thrombin that can be used for the polymerization of Fibrinogen? I need to polymerize Fibrinogen but do not want to use Thrombin for this process but could not find an alternative through my literature search. Will be great if somebody can suggest/share their experience of use of some other small/big biomolecule that can be used.

Greetings everyone,

I have the GPC data of polymerization product (contain PMMA, MMA, BPO and PVA) which shows the molecular weight (Da) vs molecular weight distribution (%). Lately, we need to obtain the mass fraction or mole fraction of its component. Is it possible to obtain the mass fraction of each component from the GPC data? Would you suggest any recommended method to measure the mass fraction of the polymerization product?

Why use solvent method to prepare polymer film is always uneven and curled （dried in a blast drying oven） and what is the relationship between the transparency of the polymer film and the degree of crystallinity?

Hi all,

I am carrying out a catalytic reaction to break down a polymer (PCL-PEG-PCL, 2k-2k-2k). I am unsure how to calculate the number of moles of polymer. Say that I want 3.0 mg of substrate. If I take the molecular weight of the polymer as it is (6000 g/mol), that would work out to be 0.5umol (u = micro).

If I want to add 5mol% of the catalyst (MW = 518 g/mol), that would work out to be 0.013 mg, which is far too small a value to weigh.

A colleague of mine suggested that after obtaining the number of moles of polymer, multiply that value with the total number of repeating units of monomers, i.e. 18+45+18, I would get 40.5umol, and the amount of catalyst I would need is 1 mg (doable). In this case, am I adding 5mol% based on the no. of moles of monomers?

I thought of calculating the amount of polymer I need based on the amount of catalyst I want to put in as well. So for example, if I want to put 1mg of catalyst to make up 5mol%, I would need 38.6umol of polymer, which works out to be 0.23g.

Pretty confused as to how I should go about this. Does anyone have a suggestion or a different way to calculate?

Many thanks!

I want to measure the contour length of collagen expperimentally

I am trying to get procedure for preparing the microcapsule by in-situ polymerization using camphor as hydrophobic core material. Using polyacrylic acid as a co-polymer and melamine-urea-formaldehyde as pre-polymers. Please suggest to me the way to make it.

Hey forum members,

I seek a micro-compounder (~5gr batches) for a clinical study batch, meaning under a GMP QA system. Simple polymer. Simple API.

Since thats a small batch I‘m looking at this stage to get it as service. Any idea where to start looking?

thanks all

i have graphene mixed with ethanol and deposited onto metal substrate and subjected below AFM cantilever, but i'm getting unusually high noises in the image recorded, whereas when the same was tried with graphene mixed with polymer i was able to record some decent images.

Params in both cases

Setpoint: 20nN

Time:1.0s

Image size: 62.5um

Points/line:256

P-gain: 10000

I-gain:1000

D-gain:0

Could anyone find out my mistake and point it out, so that i may be able to correct it.

I would like to fabricate a nanosensor for sensing application of biological molecules like cholestrol, uric acid etc

Please discuss how can I select a suitable polymer and the nanofiller (two dimensional material, MXene etc) to develop a new composite sensor material which would give good results using electrochemical workstation of three electrode system

Expecting valuable suggestions

I want to use the Archimedes principle to get the density of materials but I am not sure how to deal with samples with close pores.

Usually, polymer-silica hybrid support is synthesized by impregnation of silica nanoparticles over polymer support, which turns out to be effective all the time. Other than this method what are the alternatives for hybrd support synthesis????

I want to find the modulus of nanocomposite and see the reinforcement effect on nanocomposite by using the Halpin-Tsai model equation

I want to know that after polymerization of PDMS and before curing,what is the phase and viscosity?Does it have some visual chacteristics which show the polymerization has happened?

I will appreciate all responses.

A standard way to measure isocyanate (NCO) content in polymer is to first react with dibutylamine then back titrate the unreacted base with a strong acid. My Standard of Procedures says to dissolve sample in toluene, add dibutylamine, add isopropanol then back-titrate. What is the purpose of using isopropanol?

EDIT 1: See https://www.kyoto-kem.com/en/pdf/industry/PlasticRubber/ETII-98003.pdf for a procedure similar to the one I'm using. I am looking for the purpose of isopropanol present in large quantities, when there's already a solvent for the sample, a reagent in excess, for which there is also a (back-)titrant.

can I get a Forcefield parameter for Polyurethane polymer?

prefarable CVFF forcefield parameters for Polyurethane

I want to use pa6 for additive manufacturing. My goal is to use the components above 200 degrees celsius. My part has be dimensionally stable at 200 degrees celsius. I am confused between Tg and Tm. I know that i can use pa6 above Glass transition temperature because it semi crystalline polymer but i want to know till what temperature i can use it.

it is known that the degree of crystallinity of a polymer has obvious influence on its physical properties, such as strength, conductivity. Does the polymer material with different degrees of crystallinity show any difference in their chemical properties, e.g. chemical reactivity ?

the second question is, according to the reports, what kind of polymer has the highest crystallinity? is it possible to achieve >98% crystallinity ?

HDPE samples were aged at higher temperatures in the presence of water and CO2 than the TGA test was performed in Nitrogen? Weight gain is seen in the curve? What could be the possible reason for that?

Kindly see the curve in attached file.

I synthesized a conjugated polymer, but that's a little bit soluble in common organic solvent.(ex. MeOH, hexane, chloroform... etc.)

Except for soluble part, there remain product a lot.

Souble part can be characterized by GPC(Mn is about 1800.).

I know that the soluble part also exhibit low M.W that's hard to called polymer(monomer's M.W=170g/mol)

but, I wonder know insoluble part is polymer.

How can I confirm that?

I really appreciate your reply.

Thx.

This is a polymer heating problem.

Polymer enters at around 180C (x=0) in the barrel. Also barrel initial temperature is 180 (t=0). Some heat Is added along whole length of barrel q. We have to find exit temperature of polymer. There are heaters at 280C (r=20) along whole length of barrel at r=20 cm. Also at r=0, the temperature is 180C. exit temperature is around 250C(x=150). Also there is heat generation. Plus the polymer move with some velocity.

I decided to solve using PDE, convection-diffusion equation as polymer move from left to right along barrel.

Now how to solve as function of space and time. I am looking for some example and for inbuilt method in MATLAB.

Thanks

I am making polymer composite by solvent mixing method.

When I am trying to add filler solution in polymer solution it quickly get solidified. How to make them then uinform? It doesn't give time to ultrasonication also.

I want to calculate Jsc from EQE and want to match with Light I-V data. Could you please suggests the method?

Hello,

I am working on the photocatalytic degradation of PEG 400. I would like to know if it's possible to determine the degree on polymerization based on NMR integration, or by the MW of the polymer?

I did a quick search and found this page: https://www.sigmaaldrich.com/materials-science/polymer-science/polymer-analysis.html . However, I am not able to locate the end group proton signals due to proton exchange.

Attached is the NMR spectrum of PEG 400 at 0h. I used an internal standard (1,1,2,2-tetrachloroethane) - it's to facilitate the calculation of the yield of the reaction. I'm guessing that the stronger (more intense) signal is from the repeating units, whereas the weaker signal (around 3.4ppm) corresponds to the protons at the tail end of the polymer.

Thank you.

I want to polymerize TEOS on a surface. I know that NH4OH is a preferred catalyst and an alcoholic solvent should be used .But I can not find certain amounts of each material to use.

Does any one have experience or any reference to share?

thank u all.

Hello,

I spin-cast two different polymers onto wafers and measure their height as a function of initial concentration. For polymer A, I have the weight-average molecular weight (Mw) as well as the polydispersity index (PDI) and can thus calculate Mn. For polymer B, I only know the number-average molecular weight (Mn). Now I wonder: is it acceptable to calculate the concentration based on Mn, e.g. n = m/Mn and than c = n/V as usual for Mw?

Otherwise I'd give the mass concentration, but that renders the comparison between A + B impossible. What do you think?

Best,

Philipp

I am struggling to gain the same consistency of the polymerized gel, I am using 0.1%wt in 7g of PEGDMA, it cured sometimes into a partial gel, other times into a clumpy gel and other times into an over cured polymer. I have tried to use different light intensities by reducing or increasing the distance between the PDMS chip and the UV light (365nm). Sometimes I get results in Eppendorf tubes.

I burn Corn husks Sunflower husks after take analysis chemical the summation of AL2o3 with Sio2 become less than 60 .... CAN I PUT IN GEO POLYMER BRICK ?

I am working on a preparation of representative polymeric structures of some popular polymers, such as polyimide or PTFE for MD simulation, during which a single nitrogen or oxygen atom will be shot towards the surface.

I am preparing the polymeric cubes in the following way: 1) I pack a number of polymeric chains into a given volume to obtain a loose configuration (density of around 0.2 g/cm2), 2) I add a geometry restraint (an elastic wall) a few angstroms above the surface 3) I set the volume regime to decrease of -0.00001 in the a and b directions 4) I run a NVT simulation during which my system gets compressed to a more realistic densities, e.g. 1.4 g/cm3 for polyimide or 2.2 g/cm3 for PTFE.

My problem is that I finish the simulation with a lot of residual stress, the pressures recorded at the end of the simulations can be around 2000MPa, this does not allow me to run another simulation on the compressed structure (the atoms shooting part), because the cube just explodes. Could you suggest a way of post-processing to remove this residual stress? or maybe another approach on how to produce a realistic densities for polymers (to pack a volume to 1.4 g/cm, many polymer chains need to be added, which results in a long computation, often ended with an error that a solution could not be found). I am using the SCM software for my simulations. Thanks!

Hello everyone,

I have some PHAs blended with fillers and nucleating agents, yet I don't know what kind of fillers or nucleating agents. The producer has shut down and there's no way to get in touch with.

** Any ideas how can I identify the type of fillers and nucleating agents?

I was thinking to use EDS to identify the type of fillers, I am not sure though...

Any responses will be highly appreciated.

I am trying to avoid wet etching as the polymer is quite sensitive. I want to etch Ti, but avoid etching the polymer and gold. Ideally the temperature will be kept below 80 °C.

Basically, I would like to know how to treat or coat on the uncoated bare TiO2 (Ti-OH rich) surface with polymer which has anchoring groups in the polymer structure like trimethoxygroups. What is the basic surface coating method on uncoated TiO2?

I have synthesized PNIPAM (Poly (N-isopropylacrylamide)) microgels, which are copolymerized with oligo-ethylene glycol based comonomers. I have to determine the exact number concentration for each microgel using viscosity experiments. I wonder which formula will work to calculate the number concentration?

Dear colleagues.

How can we implement the kinetics of the polymerization of aromatic amines in easier and simpler ways?

Are there simpler methods for Nano polymers (other than those obtained with 273K and ultrasonic resistors)?

I have never conducted a meta analysis before, so I was wondering how to approach it.

Let's say I wanted to look a how a specific metric has evolved over the past 20 years, for example the reported polymer molecular weight for the highest tensile strength (the question here is arbitrary). Any pointers to how I one would go about that? Seems pretty straight forward to brute force it, albeit very time consuming.

Any help would be appreciated.

I need to spin a 120um thick film. My current procedure consists of spinning the polymer (about 20um), uv exposure, plasma etch, and then spinning another 20um thick layer, uv again, plasma etch again, then spin the third layer, so on and so forth . I was able to build up to a 120um thickness but my transparent fill turned very yellow. any suggestions? I’m currently spinning at 1000rpm. I know I can change the concentration of the polymer or reduce the speed of the spinning, but is there any other more efficient way of achieving this?

I am modeling Carbon Fiber Reinforced polymer wrapped concrete column in Abaqus, but I have faced so many difficulties especially in the Model< Interaction and Constraint module. SO could you share me related tutorials please. Even it could be CFST modeling.

In ANSYS, how to model temperature dependent polymer characteristics? I mean to say which visco-elastic material properties are important in terms of Ansys? also which visco-plastic material properties are important in terms of Ansys?

Did anybody come across this impurity at around 1800 m/z and knows what it is and how to get rid of it? I guess its a polymer and I was not able to clean it of my system with 1:1:1:1 = H2O:ACN:Isoprop:MeOH.

Thanks in advance.

We are planning to make Polymeric nanoparticles for co-delivery of 2 flavanoides. Which is the best method, that one should follow.

I am trying to find methods for theoretical calculation of enthalpy of formation of Polymers. till now I have found the oligomeric method (Gaussian) which uses the extrapolation of results from subtracting to polymer units with N and N-1 no. of monomer groups. Other method is using PBC (Gaussian) which does not take into account the terminal hydroxy groups of the polymer such as HTPB. Last method is the additive method. Is there a reliable method to perform this kind of calculations?

Also, how one can calculate the solid phase enthalpy of formation of polymer?

I want to perform the synthesis of a hydrogel and I want to know if I can polymerize NIPPAm with PEGmethacrylate or only with PEGacrylate?

Hi,

I am using a mix of 2 polymers and want to try and crosslink them. I have a UVA lamp of 365nm and have tried the lab previously at 30cm above. How would you recommend I approach the lab and what questions should I ask myself? I am looking at the excitation values for each polymer, but not exactly sure how long I should shine the UV light over the polymers for.

Thank you.

Omar

I need to draw a crystal structure for polymer, but I cannot find a dataset that contains the information needed for the certain polymer. I would like to draw it in Materials Studio. What should I do?

What is the maximum solubility limit of poly(4-methyl-1-pentene) in N,N, dimethylformamide?

I gone through solubility parameter concept but I did not get the answer for maximum amount of polymer to be dissolved in solvent.

Can we used other solvent such as n-hexane, cyclohexane chloride as a solvent to dissolved polymer?

I have made polyurethanes from methylene diphenyl diisocyanate (MDI). There is no moisture in the reaction. The final polymer is faint yellow or brown even when I used a sterically hindered phenolic antioxidant namely, Irganox 1098. The color of the polymer intensifies after heating the polymer at 160-170 deg C under pressure. The polymer is otherwise stable at that temp. The degradation temperature is higher than 170 deg C. Can you suggest anything to eliminate the color of the polymer both after synthesis and molding? Thanks

Hi Everyone,

I made some polymer(Polylactide) films on Silicon wafer. The polymer was dissolved in DCM and THF.

I observed that the colour of the film at the centre of the Wafer is different from the edges.

I reduced the RPM to 500rpm and it is still the same.

What should I do?

I want to prepare a cellulose-based biopolymer solid electrolyte by solution casting technique. However, choosing the right cellulose derivative has been my major challenge. Among the many factors to consider are amorphousness, mechanical stability, solubility in water etc of the cellulosic material. Is carboxy methylcellulose the right choice for me?

Polymerization of alkene double-bond monomer to single bonded polymer is the typical chemical mechanism, but what (other than mechanical interlocking) forms strong bond between this polymer and a metal/ceramic surface? what are the atomistic descriptions of chemical bonds at polymer-ceramic or polymer-metal interface?

I have prepared the Glass/epoxy composite specimens using the hand layup method.

I would like to test these composites for fatigue. ASTM E606 available to me.

Can I perform the fatigue testing of the polymer matrix composites using the ASTM E606 standard?

what are the things that need to be considered while fatigue testing using ASTM E606?

I am a beginner in this area, could anybody elaborate the answer?

nanoparticles coated with chitosan as well uncoated nanoparticle

Hi all,

I need to make stock solution of TFA(triflic acid) in dry dcm for ring opening polymerization.

Is it possible to place TFA in liquid nitrogen, and while is in liquid nitrogen vacuum the air out. After removal from liquid nitrogen add nitrogen flow and add the dry dcm inside.

Is this protocol possible or you have some better suggestion? Never did this reaction so ask for safest way to perform this procedure. Appreciat all the help.

Can anyone provide any insight as to why my Tris/Gly SDS-Gels are polymerizing slowly? This especially applies to my stacking gel (image attached) both 4% and 6%. The stacking gel wells polymerize slowly and are thin and lopsided.

-All buffers are kept at room temp (except 40% Acrylamide/bis-Aryclamide 37.5:1 kept at 4C)

-10% APS is made fresh

Thanks

I am separating the AuCNs, which are Au nanoclusters. I used the 3% stacking and 30% resolving polyacrylamide from the reference. Eachtime when the resolving gel is polymerizing, plenty of heat coming out, forcing some (maybe is) bubble formation. And may due to the resolving concentration is too high, the gel in the lower edge of the glass plate is difficult to polymerization. Can anyone give me a protocl or some addvice? Thank you !

Purified G actin and got 42kda band and an additional band just below it. While performing G actin polymerization and labeling with rhodamine-phalloidin I didn't observe filaments under the fluorescence microscope

I want to know the progress in the development of polymer laminated, biodegradable material based facemasks.

Any answer will be useful / Surfactants / Procedure

I am using this pre-emulsion in sequential emulsion polymerization

Hi All,

I have build the model of cellulose polymer using xleap and hemicellulose polymer using glycam carbohydrate builder. Now, I need to place the two polymer chain parallel two each other. How can I do it? Any suggestion would be appreciated.

Thanks.

A sample of Polyethylene has an average degree of polymerisation of 1200. What is the coiled length and the extended length of an average molecule given the bond length is 0.154nm and the bond angle between three adjacent C atoms is near 109.5°.

Is it possible for more than one glass transition range for a thermoplastic polymer. If so why and how? I need the exact answer of this question. Please help.

I want a fluorescent labeled polyacrylic acid. Because to check the layer coating.

However, since polyacrylic acid is a carboxyl polymer, I am not sure which fluorescent material is suitable. It would be nice if you let me know which material is better to use. Thank you.

Hi all,

I am trying to make a standard curve for Nile Blue A fluorescence using Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) as the standard and a plate reader to measure fluorescence. My issue is, I have only managed to solubilise the PHA polymer using chloroform, which then also solubilises the polystyrene plate I am using for analysis. In addition to this, chloroform does not mix well with the Nile Blue A solution I am using to stain with, which is mostly water. So my question is, is there a more non-polar solvent I can use to dissolve the PHA polymer that will not immediately effect the plate, or alternately, if I grind the polymer strips down into a powder, will the Nile Blue A still be effective at staining this?

Thanks.

I am trying to perform Gaussian optimization of a polymeric structure with 250 atoms. It is made up of only C and H atoms with several aromatic phenyl ring interlinked by C=C. Every time I am trying to optimize it is showing me a memory exceeded error. I have also given 50 GB as %mem but still no use. Can anyone help?

Require an alternative way to analyze the chemical structure and polymer origin of microplastics without μ-FT-IR. Since μ-FT-IR is very expensive to run samples for analysis, any alternative approaches would be very useful.

i want to deposit film of polycarbazole over silicon wafer through three electrode electrochemical cell.

I would like to know if the properties of a polymer impact on the size of the particle it forms. I'm working with different polyssacharides (alginic acid from different seaweed), which are precipitated by the exact same method. Is it to be expected that the mean particle size of the polymers are different (because of molar mass, polydispersivity, monomers ratio, polarity - one of them has high hydroxyl content -, branching...)? Or is the particle size normally an exclusive function of the process and not the chemical nature of the material?

What can be done to precipitate polymer nanoparticles, such as polydopamine when it doesn't precipitate at 10000 rpm for 15 minutes??????

Dear Researchers,

I am a researcher and I am working on a Xenon accelerated aging of a polymer and I need the ASTM G 155 standard. I will be grateful if someone can share it with me.

Best wishes all

Please suggest the applications for stable polymer based metal composits

I am in search of a polymer which has a solubility in oil.

Generally, how we can find a substitute for a specified material?

I'm working on polymer.

I've tried 8mg sample in 0.6 ml solvent for 13C NMR but I got a high noise spectrum.

Any specific amount for polymer sample in running NMR ?

I have synthesized electro-chemically AuNPs with some stabilizers. To know the exact molecule, capping the NPs (to know if the capping agent has polymerized), Is it right to perform a GC-MS?