Electrostatics of Balloon
To understand why the balloon stick to the wall
When two bodies are rubbed against each other, the charges gets transferred from one body to another. The charges are not created by rubbing.
Rub the balloon on your shirt (except cotton). Take the balloon close to the dry wall. You will observe that the balloon gets stuck to the wall.
When the balloon is rubbed to the shirt, some electron gets transferred from shirt to the balloon. Normally, there are equal number of protons and electrons in a neutral object. But, when the excess of electron accumulates on the balloon, it gets negatively charged. When negatively charged balloon is brought near to the wall, the electrons on the surface of the wall are repelled. Thereby the wall gets positively charged.
Unlike charges attract each other. Hence the balloon get stuck to the wall. If the wall is wet, it will lose the charge very quickly. The same thing happen if the air is humid. Hence, the wall has to be dry.
If the balloon is kept close to the wall for long, then the excess electrons from the balloon will flow back to the wall. The balloon will become neutral and will fall. Moreover, if the balloon is kept for long, it will gradually collapse.