Solubility of polymers might be explained by the dissolving rules of linear polymer or the Hildebrand relationship.

The enthalpy change on mixing of a polymer and a solvent, whole volume of the solution, volume fractions for solvent and polymer and solubility parameters for solvent and polymer impact on the solubility of the polymer in a solvent.

If the solubility parameters for the solvent and the polymer are close to each other, the solvent will be good for the polymer. Thus, the polymer solubility can be predicted.

ref:

Article Solvent-, ion- and pH-specific swelling of poly(2-acrylamido...

Tayebe, you can estimate the solubility parameter from methods such as group contribution and then use the concept of the Hansen solubility parameter (the first link that Pavel provided above) to examine the possibility of dissolving a polymer in the desired solvent. You should consider that these equations do not consider any specific interactions between the components! For estimation of the solubility parameter, the chapter 7 in the book of van Krevelen (properties of polymers) is a good reference.

Dear Ebrahim, really thanks for your explanation.Chapter 7 of properties of polymers is very useful.

Search for the Solubility parameter d (delta) of the polymer ans the solvent. the closer they are the more the solvent will solve the polymer. Approximative Example: Polymer: PMMA d=9, Solvents: H2O d=23, MMA d=10 . The solvent that will solve PMMA better will be MMA.

(NOTE: the solubility parameters reported are not real, have just be taken for demonstrative purposes)

It is important to note that the higher the polymer's molecular weight, the closer the solubility parameter of the solvent needs to be if you want to get a polymer solution in that solvent.

Sometimes the use of some mathematic parameters (such is the Hansen parameter -the first link provided by Pavel) can give you an idea of the solubility of a mixture. Nevertheless, these use to be just approximations and do not consider specific interactions between components. In this sense, a deeper look to your system should be necesssary to fully-explain the final solubility of the mixture. I am in totally agreement with Ebrahim Jalali Dilhe's porposed book.

The solubility parameters are much better elaborated and much more useful than most people believe. Hansen solub param are 3-dimensional, not just only simply rough approximations! I recommend to use this book:

http://books.google.com.hk/books/about/CRC_Handbook_of_Solubility_Parameters_an.html?id=aZ-7pyH1cR4C

I have used it very intensively and with good success. It also shows and explains usefulness and limitations.

The solubility parameter which is based on the cohesive energy density is a simple approach to understand substance dissolution and it is never a tool to quantify or predict solubilization. The best examples are polyolefines and fluoropolymers (PTFE) which fail to solubilize in any known solvent even at high heating.

This cohesive energy is by the way the reason behind the non-evaporation aspect of polymers, it increases with the chain length rendering even more difficult the solubility of a given polymer. The equation of the solubility parameter use the evaporation thermodynamic parameter which is the latent heat, and since polymers does not evaporate the use of the classical Joël Hildbrand parameter in question.

So, to the best of my knowledge will be to check the solubility of a substance by doing experimental tests, by taking the polar/apolar character of the substance/solvent in question into account.

Dear Andrei Rogoza, and thanks for the remarks, however one should differenciate between melting or suspension (which is the best that we can do for the aforementioned polymers when we try to solubilize them in a solvent at high temperature), real solubulization never can be achieved on the molecular level, which means solute-solvent coexist on the neighborhood. It is in fact almost the same situation where Prof. Bernhard Wessling stress (for many time) for the case of the solubility of conducting polymers.

I disagree with Aek Aziz, please let me explain why:

Solutions are possible if for the dissolution process

delta G = delta H - T*delta S < 0.

However, delta H is not just only the solvation enthalpy, but for (partially crystalline) polymers, you also need to overcome the melt enthalpy (you have to invest it!). For a good match between polymer and solvent, the crystallites melting enthalpy can be provided by the good solvent.

But in some cases (also due to high molecular weight of the polymer), the solvent can't, so you have to introduce the necessary energy for melting by heating:

- the low molecular weight eicosane is nicely soluble in hexane

http://lxsrv7.oru.edu/~alang/solubility/soltemp.php?csids=7929&cs=2.788&solvent=hexane&solmp=-95&solbp=68.5&limreact=0&limprod=0

- high molecular weight polyethylene (which we could also call here "polyeicosane" just for the purpose of illustration) is insoluble in hexane, but soluble in decaline at high temperature: why decaline? because you can not heat hexane as high as is needed to melt the polyethylene crystals.

Then why no solvent for PTFE?

- because PTFE melts at 600 K, there is no solvent with the appropriate solubility parameter which you can heat as high to melt the PTFE crystals.

The melt enthalpy aspect is not accounted for in the solubility parameter theory, neither in Hansen's, nor in Hildebrandt's theory. When using solubility parameters, you should know this and account for, not reject the solubility parameter concept.

Please let me add the following:

in a previous comment, I wrote " the higher the polymer's molecular weight, the closer the solubility parameter of the solvent needs to be if you want to get a polymer solution in that solvent".

Why is this? it is first for entropic reasons (the monomer units which need to be solvated by the solvent can not have an unlimited number of configurations in space as a low molecular weight solute can attain, especially not with respect to neighboured monomer units);

but also for solvatation (enthalpic) reasons: for a monomer or a small molecule ("sugar"), the solvent can and will and must (!) surround it from all directions (3-dimensionally), so you have a lot of solute-solvent interactions; for an oligomer, the inner monomer unitscan only be solvated circumferentially, while in the oligomer axis, there are other monomer units; only the monomer units at the end of the chain can be solvated from 3 directions (not from 4 as "sugar" can be!);

the longer the polymer, the more monomer units can only be circumferentially solvated.

another comment to Andrei Rogoza:

I have not directly worked on solubility parameters, I was only a practical user of these concepts for 3 decades (and tried to understand them a little deeper than only from surface). Therefore I can not offer a paper which you may look for as an "out-of-box information".

What I can offer is one paper where I applied the concept (it is a book chapter):

https://www.researchgate.net/publication/253651172_Conductive_Polymers_as_Organic_Nanometals

Then you go to par 2, p 525

When reading the whole article or at least that subchapter p 5252 ff, you can find some confirmation for what you wrote:

- for molecular weight determination, it is very important to know whether one has a true polymer solution, or maybe already over-saturated (which the higher the molecular weight, at the lower concentration is the case!),

or, as in the case I am discussing there,

- one can not determine molecular weight by GPC at all because the polymer / solvent system one is looking at is not a solution but a dispersion! (as is the case which I was working on)

Chapter Conductive Polymers as Organic Nanometals

one more comment to Andrei Rogoza (your comment crossed my last ones in time and space):

as we are discussing about atmospheric pressure conditions (and solubility parameters apply - as far as I know - to these conditions as well), and the average polymer scientist is working on earth and not on Jupiter :-), my comments for hexane are valid;

I would not be surprised at all (I never tested, and I never searched in literature) if hexane could dissolve polyethylene under high pressure at high temperature, but then what? no practical use, but some confirmation for solution thermodynamics :-)

re PTFE and perfluorokerosene, I did not know, interesting, thanks! and it also confirms what I commented,

Andrei, you will certainly be one of the very few people in the world having read this paper (completely?) and still say "easy to understand" :-)

thank you, and I hope you don't just send kind words :-)

Yes, I agree, I am also not sure what exactly a solution of sodium in ammonia looks like ... but for the discussion topic here, it would probably lead us into some deviation, if not a dead end ... :-)

What I wanted to show in my paper is the non-linearity of the Na/NH3 system which also indicates this may not be a true solution but a dispersion! (p 537).

- which would mean: we do not have isolated Na atoms in the NH3 "solution" (= not a true solution, but a dispersioN!), but Na clusters of whatever size. as you said: 10, 100, 1000 atoms?

- needs to be carfully determined (if one wants to really know)

Dear friends,thank you for your useful comments. I learned a lot.

I agree with Bernhard Wessling.

Dear all and especially to Prof. Bernhard Wessling for the nice contributions.

To Tayebe Khosravi, I was looking for some papers which I studied in the past on the subjet of solubility, among these, the following link I think wil provide you with a good starting: LA Utracki and R Simha ' Statistical thermodynamics predictions

of the solubility parameter '; Polymer International; Vol.53, pp.279–286 (2004). link: DOI: 10.1002/pi.1365

as we know if difference of solubility parameter between the polymer and solvent be less than 0.5 that is a good solvent for that polymer, but in reality bad solvent could solve the polymer a bit. And if there are two kind of polymer which one of them is good soluble in solvent its difficult to say how much of the other polymer will be in the solution, it vary with the effect of two polymer's solubility parameter on each other.

Although after mixing the polymer(s) in the solvent, if it's transparent and clear you can't say there is a homogeneous solution as all above say it is a good dispersion and by letting some time for resting solution the chains of polymer(s) will precipitated. I found it for PS in Acetic Acid which by literature shouldn't be any but there is some.

It is a widespread misunderstanding that clear transparent solvent / polymer systems always are true solutions. Some may instead be dispersions, and if the particle size of the polymer particles is less than 2-300 nm, then the solvent/polymer systems appears to be a solution, but still is a dispersion! (and will be stable!)

For a true solution, all monomer units must be fully surrounded by solvent molecules, and MU / MU interactions must completely be replaced by MU/solvent interactions. True polymer solutions are more rare than you think: many polymers can only be truely soluble at low concentrations, above that they are partially dissolved, partially just swollen, so some mixed thing between solution and dispersion.

The conductive polymers which I had worked on had all been definitely insoluble, they formed (if well done) nice and very stable dispersions, transparent (but coloured, as these polymers absorb in the nisible range).

Flory-Huggins theory explains the relationship between Mw and concentration (entropy), Enthalpy (solubility parameters) and temperature,

.

http://en.wikipedia.org/wiki/Flory%E2%80%93Huggins_solution_theory

CRC Press (Boca Raton, Florida) publishes a fine book called "Handbook of Solubility Parameters and Other cohesion Parameters," edited by Allan F. M. Barton (739 pages; ISBN 0-8493-0176-9). In it you will find excellent descriptions of 3-dimensional parameters, which are essential to understand "solubility" of polymers. The older 1-dimensional parameters are not very useful. The 3D versions introduce polarity effects and hydrogen-bonding effects which substantially improves the utility of the concept. Solubility is achieved when all three components match up within a small range. I personally used the Hoy parameters, but my impression is that the Hansen parameters are also useful.

I spend decades in the coatings industry, where I regularly used these for both solvent borne and waterborne polymers. In spite of literature claims at the time to the contrary, I found that I got very good results for so-called water-reducible polymers which were acid functional and required a blend of a water-miscible co-solvent with water in addition to neutralizing the acid groups to achieve a proper stable dispersion with very small particle. While not literally a "soluble" result, this turned out to be an excellent guide to achieving minimal particle size and stability.

I was also able to use 3D parameters to design coalescing solvents for latex polymers that were permanently retained the subsequent films, thereby achieving zero VOC (volatile organic content) for the system. The key was in matching the H-bonding parameter in particular for coalescent molecules that were a few thousand in MW. Surprisingly, they would diffuse into the particles rapidly (within the time of the total experiment of 4 hours), but resisted diffusing back out either in the latex form or in the film form. We speculated that this was due to the large number of polymer-coalescent interactions per molecule that simply exceeded the exchange rate of the total sites of interaction.

US Patent 5,326,808 by Floyd and Craun describe the essence of some of our work. Examples 46 and 47 demonstrate that coalescing solvents properly matched in solubility parameter to the polymer being softened will be non-migrating after the film is formed, as mentioned above. We used tables of parameters such as those listed in the CRC Press handbook described above to achieve this unique match-up. [Note that while we used a micro suspension polymerization process, we later were able to demonstrate that we could also use standard emulsion polymerization processes and depend on normal diffusion to imbibe the coalescing solvent into the latex polymer by simply dispersing the coalescent into the latex post-polymerization.]

But the key point of my answer is to get a copy of the CRC Handbook of Solubility Parameters and learn first hand how this all works. The tables of parameters are worth the price of the book alone.

Lou Floyd

By the way, from the CRC press handbook, the Hoy solubility parameters for ethanol and ethylene glycol dimethyl ether are as follows:

ethanol -- dispersion 12.6; polar 11.2; h-bond 20.0; total 26.1

EGDME -- dispersion 13.0; polar 10.0; h-bond 17.4; total 23.9

There is no single set of parameters for a given poly glycol, since they would depend on the degree of polymerization, which in turn would determine the number of ether groups and residual OH groups. If you know the approximate DP, then a quick count could be used to calculate the parameters, as described in the Handbook.

F. Floyd, I agree, this book is excellent, I used it all the time as well, this book was constantly on my desk.

Morton, this is indeed an important aspect, which I had highlighted in another discussion here on RG, about Polyaniline solubility, and there I mentioned my extensive article about solubility, covering experimental and theoretical thermodynamical aspects including the effect of crystals on solubility. May you or others are interested in it:

https://www.researchgate.net/publication/253651172_Conductive_Polymers_as_Organic_Nanometals

Chapter Conductive Polymers as Organic Nanometals

The good solvent is that which is in the center of the sphere Hansen solubility. It may be that it is a single or a mixture of liquid. If you want more details, see my post: Ahmed Belfkira, Jean-Pierre Montheard: Solubility parameters of poly (4-Substituted α-acetoxystyrenes) and Copolymers of vinylidene cyanide alternating with Substituted styrenes.

This attach may be useful

some people asked for some link to Barton's Solubility Parameter Handbook:

http://www.amazon.com/Handbook-Solubility-Parameters-Cohesion-Edition/dp/0849301769

(I am not a professor, just a simple chemistry doctor with some experience)

At high concentrations (and 10% is extremely high!), even truely soluble polymers are not completely dissolved, therefore it can happen what you observed. The reason for this is that you need enough solvent molecules to completely solvate EACH monomer unit, AND you must have enough solvent molecules left which are not occupied with solvatation jobs, but freely mobile.

I am not sure whether 1% is dilute enough for a 300,000 Mw polymer, Flory-Huggins theory may help you to calculate.

This link may help you as well, I did not read in detail:

http://ptgmedia.pearsoncmg.com/images/chap3_0130181684/elementLinks/chap3_0130181684.pdf

This link may also be helpful, but I did not succeed yet in opening it:

http://nsdl.niscair.res.in/bitstream/123456789/405/1/Solution+Properties.doc

I found another interesting web site for a more general introduction into solublity parameters:

http://cool.conservation-us.org/coolaic/sg/bpg/annual/v03/bp03-04.html

As you suspected, the solvent solubility parameter changes with temperature for two reasons. First, the solvent expands and since cohesive energy density (CED) is measured as Joules per cubic centimeter, a 10% expansion lowers the CED by 10% and the solubility parameter by 5%. Also, the higher temperature decreases cohesive interactions since the molecules rotate faster and this lowers the CED more. DMF has a very high solubility parameter value and may only be a solvent at high temperature; polystyrene has a relatively low value. In fact DMF is listed in the Polymer Handbook as a non-solvent. However, phase diagrams always curve with concentration. It is possible that it could dissolve 1% of polystyrene.

You might try DMAc instead. Its solubility parameter is 22.1 vs 24.8 for DMF and 18 to 21 for polystyrene. We have used it as a solvent for polystyrene in GPC measurements. The Polymer Handbook shows that tetramethyl urea has the right Hansen solubility parameters to be a very good solvent for polystyrene and may be polar enough for your other material. Also you could use a mixture of solvents to increase solubility without loosing reactivity.

Higher the polymer's molecular weight, the closer the solubility parameter where temperature and concentration can affect the solubility of polymer.

I agree, I will write it in different words: the higher the polymer's molecular weight, the closer the solubility parameter of the solvent must be so to enable solubility; low molecular weight polymers or oligomers may be soluble in solvents having a solubility parameter differing from the polymer / oligomer ones, the same solvents may not be able to dissolve the "same" polymer when it has a higher molecular weight.

You are in luck!

I wrote a series of programs available in a dictionary from Springer publishing, but attached for download for your convenience. This is a simple plug-in value that will save you much time. (Link to Springer Publishing polymer programs – Dr. Jan W. Gooch (404 403 0047, [email protected]

http://extras.springer.com/2011/978-1-4419-6247-8)

Good luck,

Jan

by the way, for my previous answer

"I agree, I will write it in different words: the higher the polymer's molecular weight, the closer the solubility parameter of the solvent must be so to enable solubility; low molecular weight polymers or oligomers may be soluble in solvents having a solubility parameter differing from the polymer / oligomer ones, the same solvents may not be able to dissolve the "same" polymer when it has a higher molecular weight."

there is some thermodynamical background: the entropic term in dissolution free energy.

Please refer Polymer Hand Book , the solubility parameter of the solvent should be either close or slightly higher than that of the polymeric solute to be dissolved.

Please see the attached article which offers simplified account of polymer-solvent solubility parameters

If we take .1 gram PEGDME,and try to find out the solubility in various organic solvents . Try to find out the amount soluble in solvents. On the basis of solubility, we can calculate %of solubility and we can select suitable solvent for solubility.

You should know that the best solvent of a polymer is a liuiqde with forces of secondary interactions similar to those of the polymer (Van Der Waals and hydrogen bonds). To find it, you have to test your polymer solubility in a variety of solvent and determine the center of the sphere of solubility (best solvent for the polymer). You can find more details in:

Solubility parameters of poly(4-substituted α-acetoxystyrenes) and alternating copolymers of vinylidene cyanide with substituted styrenes

Ahmed Belfkira andJean-Pierre Montheard, Journal of Applied Polymer Science

Volume 51, Issue 11, pages 1849–1859, 14 March 1994

LIke dissolves like c'est la règle la plus simple.il faut utiliser la formule de Hilderbrand avec les paramètres de solubilité de votre polymère et choisir un solvant ayant paramètre proche. I faut aussi penser à utiliser un mmélange de solvant.

Vous avez raison Nacerddine Haddaoui.À mon avis.

The statement given by learned academician is very correct ,provided you know the molecular weight,then and then only one can say low / high molecular weight polymer.

So first find the molecular weight and then apply the suggestion given by learned academician. So use the classical methods select the best solvent in which polymer is dissolved in cold as well as hot conditions.

Is there a lowest solubitly of polymer with a certain molecular weight distribution?

in my research , i find that a linear polymer with a number molecualr weight 4500D, PDI 1.37. It can disolve in water at concentration 25wt%, but when we diluted it to concentration 0.5wt%, we found some polymer precipitated. so i am curious is there a lowest solubitly of polymer with a certain molecular weight distribution? any one can offer some exsamples ? thanks.  

I do not believe that a concentration of 25% represents a true solution, it will only be partially dissolved, partially dispersed / swollen. The result when diluting tells me that this polymer (whatever it is) is not truely soluble.

Apart from that, I do not fully understand your question: "a lowest solubility"? are you looking for a polymer which has the lowest solubility compared to any other polymer in whatever solvent?

I did not meant to up vote the question of Carl. But also did not wanted to down vote it.

I would speculate that a fraction of the product you investigated is insoluble in water.

At 25 % you may not observe this fraction as it was stabilized by the soluble or highly swollen compounds. So likely a critical lower solution concentration might not exist.

By the way, I think putting your own question would be more appropriate to do separately because it does not match the original question very much.

the polyme i am study is a amphiphilic copolymer , sythesis by ring-opinging polymerization. usually botain a PDI 1.2, and as the number-average molecualr weight is only about 4500. i am sure it can disloved in water at 25wt%.  but after i obtain the wider PDI by mixing , with semilar number-average molecualr weight, it still can dissolve in water at high concentration. but precipated after dilution.

and some teacher told me that usually polymer have no the higest solubility , but having the lowest solubility. and molecuar weight distribution is a key factor... the light weight molecuaar is a cosolvent as high concentration , when diluted,the amount of light weight molecular is not enough to solubilizing the heavy part. here i hope someone can offer me some exsamples. any polymer in whatever solvent..

ps: sorry for tayebe khosravi. i tried make a new topic about my solubility questuon, but no one pay atension to it , till i find ur interesting questuion , and some researcher are active here , so i put my question here , hope u don`t mind.

As a general rule, for linear and branched (but not crosslinked) polymers, a plot of solubility vs solubility parameter for a range of solvents will peak when the solubility is matched.  For lightly crosslinked polymers, the swell volume will peak when the solvent solubility parameter matches that of the polymer.  The lower the molecular weight of a linear or branched polymer, the greater the solubility.  At very low MW's the liquids are miscible when the SP is a match.

Carl, I assume what you have as "solution" at high concentration is a colloidal system, not a solution. Your polymer will not be truely dissolved, but dispersed and swollen.

Already when you say "low molecular weight portoins of the polymer act a co-solvent" this supports what I say (apart from that your statement is an assumption, not a conclusion from analysis). 

A polymer is only in solution if ALL its monomer units, ALL its chain elements are COMPLETELY surrounded ("solvated") by solvent molecules.

In case of your 25% "solution", I tell you: there are not enough water molecules to completely solvate all the chains, all the monomer units, and if there were, this system with 25% would be a solid gel (no free water molecules any more, extremely high viscosity ==> gel) 

If my assumption is correct, then the low molecular weight portions of the polymer help to generate the colloiudal system and function as a dispersion agent.

When we talk of a polymer solution, we must not speak of average mass or concentration. Solubilization as Bernhard Wessling said macromolecules are completely surrounded by solvent molecules: single phase less or more viscous (depending on MM).

NB: The solubility tests: a few milligrams of polymer in a few cubic centimeters of liquid

In summary, in my experience, the best way to find a good solvent for a polymer (linear or branched but not chemically or physically crosslinked, non-crystalline (amorphous))  is to use the parametric model C. Hansen.

Good luck.

THE SOLUBILITY PARAMETER IS A USEFUL TOOL IN DETERMINING THE SOLUBILITY OF ONE SUBSTANCE IN THE OTHER EG IN POLYMERS. THE CLOSER THE VALUES THE MORE LIKELY THE SOLUBILITY OF THE SOLUTE IN THE GIVEN SOLVENT. CHECK SOLUBILITY TABLE FOR COMPARISON

hello,  in some systems there is use of double cross linkers with more than one pore generating solvents. in this case, how can we calculate the Solubility parameters? which basis would be more suitable and idea, Hildbrande or Hansen? anyone has experience in this? i would appreciate feedback. 

solubility parameter (Hansen should be more conclusive) do not show the effect of cross linking. What would be different is in case of low to medium molecular mass polymers without cross linking you will obtain a solution. Otherwise you will observe swelling only depending on molecular mass and degree of cross linking. Solubility parameters are about thermodynamics not about kinetics.