An Experement

[wildbillbugman]

Hello To All
Several weeks ago I began evaluating a commercialy availible Silane Treated PVOH in substitution for my Homade Silane treated PVOH (That I have been substituting for gelatin in silver halide emulsions) Results are the best I have ever had, not only for silver-halide emulsions but as a carrier for Pt/Pd/Au/Pigment on glass. I have long known about these polymers,from the middle and far east, but have never befor been able to get a sample. Kuraray America is a Japanese company with an office in TX or IL. I here website is www.kuraray-am.com. They sent me a free 1lb sample of there R-1130,The higher viscosity of two viscosities availible. After making several simple emulsions, I will probablky never silane treat PVOH myself again.
Anyway, I made a small batch of panchro emulsion in which, instead of splitting, the batch into three parts AFTER precipitation, I split the ammoniacle silver solution into two parts. I then added S/Au, in the form of Steigmman's Solution to both halves. Then I added Sands SDE3008(green senstizing dye) to one half and SDA3057(red sensitizing dye) to the other. Interestingly, the SDA3057 turned Cyan (the objective) dispite the fact that no Iodine was present.
I combined the two halves and added formalin. Coated onto glass, about 6 mils wet thickness. The next day I exposed through red,green and blue separation filters. The sensitivity of the red exposed plates was only slightly weeker than the green and blue exposed plates.(BTW-The color of the emulsion itself is bright lavende).
I am very much incouraged.
If anyone is interested in more detale,ask and ye shall receive. I have no secrets.
Bill

 

[wildbillbugman]

For clarification, I should say that the two halves of the ammoniacle silver/dye/steigmann's solution were added,one at a time to the Resin/Br/I solution under shear of 1200rpm.
Bill

 

[dwross]

Congratulations! I love it! I am truly inspired by your scientific persistence and integrity and your artistic vision. Your bug macros are gorgeous. You're definitely in my 'cool dude' pantheon, sir.
, d

 

[holmburgers]

So, do I understand this correctly... you're not using gelatin at all?

 

[wildbillbugman]

Yes,
That is correct. Not a mg. of gelatin.
Bill

 

[holmburgers]

That seems quite incredible to me. I'd love to know more, but I just don't know what to ask. Perhaps I will after the emulsion workshop...

 

[Photo Engineer]

Bill;

How did you harden it?

PE

 

[wildbillbugman]

PE,
Formalin. But I am not convinced,yet, that any hardener is required. HOT water will soften the emulsion, or hot water will soften a solution of the polymer in waster,after drying on glass. But when cold it is hard and virtualy imposible to get tthe solution or an emulsion made of this polymer off glass.

Bill

 

[Photo Engineer]

Bill;

From my days coating PVA, I remember that it is not noted for being hardenable, so another site must be present. We used to add other active sites for hardening. I wonder what the reaction might be. Nothing occurs to me OTOMH.

Thanks.

PE

 

[T-grain]

Bill, that thing you started looks very interesting to me! If you can share some more details about, I would be more than glad! I have a question though: did you use the silanized PVOH just for a better adherence to glass, or also due to its (somewhat) different properties compared to plain PVOH? At which temp does it set?
thanx in advance

 

[T-grain]

Ron,
couldn't be PVOH hardenable (at least in an alkaline medium) by using boric acid? Or perhaps using glutaraldehyde?
regarding its mechanical/optical properties, does it differ much from gelatine? were there any attempts for using PVOH in photo emulsions?
since there are also some PVA variants available functionalized with anionic (and cationic) groups, couldn't be that stuff hardenable by just adding an aluminium salt?
thanks

 

[Photo Engineer]

It is more common to use Acryl Amide, Poly Vinyl Pyrrolidone or Butvar in emulsions, and none of these nor Poly Vinly Alcohol resemble gelatin in any way. Gelatin has a structure which is imposed by its protein makeup. The amino acids act to peptize gelatin and it can chill set and crosslink. The others can, but under conditions often harmful to the silver halide grains.

The Silanes probably add something to the mix to improve the activity of the vehicle with the AgX crystals. IDK. It also may supply hardening sites. We usually used a site with an active methylene on it so that we could harden.

I've worked extensively with polymers in order to replace gelatin. It is not an easy task. I await Bill's results.

PE

 

[T-grain]

Ron, what do you mean with a site with an active methylene-on which polymer? gelatine?
so PVP could be a "lousy" substitute for gelatin?
I am also very curious about Bill's results!
thanks

 

[Photo Engineer]

Gelatin has active cross linking sites that work with formalin or other hardeners. These are amine based. Other active sites which can be placed on polymers are -C=O CH2 C=O (this is hard to draw and explain). In any event, Poly Vinyl Alcohol by itself is difficult to harden and has no sites to peptize Silver Halide grains as they form.

Therefore, something else (Silane?) is helping Bill. I am curious as well.

PE

 

[Kirk Keyes]

It is more common to use Acryl Amide, Poly Vinyl Pyrrolidone or Butvar in emulsions,

Butt-Head: Whoa, huh huh, he just said "Butvar!"
Beavis: Yeah, Heh heh heh eh eh eh heh heh heh.

Sorry...

 

[Kirk Keyes]

Silanizing agents attack compounds that contain hydroxyl groups by displacing the alkoxy groups on the silanizing agent and forming a covalent -Si-O-Si- bond.

It seems to me reacting a silanizing agent with Polyvinyl Alcohol will just add the silane to the alcohol groups - it will add mass to the PVOH chain, but not crosslink anything.

Also, to those reading that don't have experience with silanizing agents, they are kind of nasty compounds. You need to take real care when handling them. They are toxic through contact with skin and corrosive - that is they react with your skin as well.

 

[T-grain]

Kirk, actually we don't know how the PVA (in this case) is derivatized, crosslinked or not. The Kuraray site states that it has silanol groups. therefore, these are probably more or less Si-OH groups which can interact with glass surface by hydrogen bonding SiOH......HOSi and of course within the polymer itself
I have first-hand experience with silylating (mostly trimethylsilylating to be precise) agents, since we use them in our lab for GC work. They are really useful stuff (greatly extend the volatility range of coumpounds), but yes, they are really nasty to work with.

 

[Hologram]

Kirk, actually we don't know how the PVA (in this case) is derivatized, crosslinked or not. The Kuraray site states that it has silanol groups. therefore, these are probably more or less Si-OH groups which can interact with glass surface by hydrogen bonding SiOH......HOSi and of course within the polymer itself
I have first-hand experience with silylating (mostly trimethylsilylating to be precise) agents, since we use them in our lab for GC work. They are really useful stuff (greatly extend the volatility range of coumpounds), but yes, they are really nasty to work with.

It's been made probably along these Kuraray's patents: US 4617239 and US 4567221.

 

[Kirk Keyes]

I have first-hand experience with silylating (mostly trimethylsilylating to be precise) agents, since we use them in our lab for GC work.

Same here.

What GC stuff do you do? I run air for volatiles with GC/MS (TO-15) and various drinking water and waz waste methods for water and soil with ECD or FID detectors.

 

[T-grain]

Same here.

What GC stuff do you do? I run air for volatiles with GC/MS (TO-15) and various drinking water and waz waste methods for water and soil with ECD or FID detectors.

As for silylation, we do mostly aminoacids and other similar stuff (cannot disclose everything, sorry ). Otherwise, we do mostly food and pharma analyses, a wide array.

 

[Photo Engineer]

Lost in this all is the fact that nothing here seems to supply a means of hardening the polymer, but it does appear to have some properties that allow adhesion to the glass. Will it work on film support?

PE

 

[jeffreyg]

All this is way above me. I am a dentist and use silane as a coupling agent to coat porcelain restorations prior to bonding them to teeth with resin cements to enhance the bond. Using it with the emulsion to coat glass plates is probably works in a similar fashion. As a dental product silane is over $50 for 12ml.

Just thought this may be of interest.

http://www.jeffreyglasser.com/

 

[Marco B]

All this is way above me. I am a dentist and use silane as a coupling agent to coat porcelain restorations prior to bonding them to teeth with resin cements to enhance the bond. Using it with the emulsion to coat glass plates is probably works in a similar fashion. As a dental product silane is over $50 for 12ml.

Just thought this may be of interest.

Maybe a bit similar, from Wikipedia:

"Several industrial and medical applications exist for silane and functionalized silanes. For instance, silanes are used as coupling agents to adhere glass fibers to a polymer matrix, stabilizing the composite material. In other words, Silane coats the glass fibers to create better adhesion to the polymer chain. They can also be used to couple a bio-inert layer on a titanium implant."

 

[wildbillbugman]

Hi Everyone,
It is quite possible that, in my recent emulsions, the formalin just sat there doing nothing. However,last night I did a quick search of crosslinkers for PVA. I not only found refferences to formalin and glyoxal, but to borax and even to bromine salts. Rather than argue over it, I plan to do some experements. I will compare the water solubility of films made from Kuraray silane / PVA with and without formalin and some other components of the emulsion.
Yes, silane coupling agents are toxic. That is one reason to use Kuraray product instead of pure coupling agents. But I think that, for me, it is way too late to worry about it now. I started working with organo-silanes in 1974. I am careful, but time is time and quantity is quantity.
Moe later,
Bill

 

[wildbillbugman]

An Expriment

Bill, that thing you started looks very interesting to me! If you can share some more details about, I would be more than glad! I have a question though: did you use the silanized PVOH just for a better adherence to glass, or also due to its (somewhat) different properties compared to plain PVOH? At which temp does it set?
thanx in advance

Actualy, adhesion to glass is the whole thing. Although silane groups replacing hydroxyls will decreace watersolubility. In another study, I replaced all of the OH with silane . The resulting polymer was totaly insoluble in water. The Kuraray polymer is fairly easy to disolve in NEAR BOILING water. So there must be relatively few silanes, relative to hydroxyls.
Unlike gelatin, a PVA based emulsion dose not "set up". It must be alowed to dry.