What do you mean changing the Ph of the juice and the molecular size of the nicotine? Lost me a little there. The acidity of the nicotine juice would probably vary through flavorings and additives (whether factory or added by suppliers), making the ph different for every available flavor/type, not to forget to mention different from the few manufacturers there are.
Nicotine, on a molecular level....how much smaller does it have to get to be absorbed in the lungs? The nicotine is being carried by the vapor, therefore, hold in till the vapor is reduced or gone, and viola....absorbing, near 100% Similar trait to analog cigs, except, not recommended holding the cigarette smoke in this way. If the nicotine in the ejuice can already be absorbed dermatologically, wouldn't the porous inner walls of our lungs absorb the nicotine to a greater degree?
Seems to me, eliminating re-sellers from re-bottling would eliminate the variable ph and variable quality of the e-juice. (This is the only market that I am aware of that this is acceptable. Someone buys a bottle of Coke-Cola, adds Cherry flavoring, re-bottles it and would you buy it?)
As for the nicotine intake, I would imagine it would be as simple as changing the way you inhale, hold, and exhale.