Gel - Decision tree gel
8 important questions on Gel - Decision tree gel
What happens with the gel strength of a polymer gel (helices) when the charge is increased?
- Decrease: more electrostatic repulsion, so helix formation is more difficult --> less strong network
- Increase: more repulsion, so the strength in between the contact points can become stiffer --> increasing gel strength
What happens with the gel strength of a polymer gel that gelates due to salt-bridges when salt/calcium is added?
- Decrease: too much calcium creates too many contact points --> no formation of 3-dimensional network
- Increase: more charged, more contact points/stronger interactions for the polymer to form a gel --> can show syneresis when unstable
How is a stable particle gel formed?
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You have a gel (mixed system) of polymers + large particles, the gel strength decreases due to electrostatic attraction, how come?
- Particle withdraws polymer from network --> creaming/sedimentation (depending on kinetics). Phase separation and partly gelation can occur
- With large particles, network formation is more difficult. Particles are disrupting network formation. Take space and only small networks can be formed.
You have a gel (mixed system) of different polymers, the gel strength decreases due to electrostatic attraction, how come?
- Salt bridges: the two polymers form a complex with the help of a salt. This can precipitate. Depending on the kinetics a turbid gel can be observed.
- Oppositely charged polymers: the two polymers form a complex with strong interactions. Precipitation occurs. Depending on the kinetics a turbid gel can be observed.
You have a gel (mixed system) of different polymers, the gel strength decreases due to electrostatic repulsion, how come?
You have a gel (mixed system) of different polymers, the gel strength increases due to electrostatic repulsion, how come?
- Single network: 1 polymer gels and the other fills the space and interacts with water. The concentration of the network polymer increases and a stronger network is created.
- Interpenetrating network: both polymers formed a network. A stronger gel was formed
You have a gel (mixed system) of different polymers, the gel strength increases due to electrostatic attraction, how come?
Concentrations too high: depletion interactions --> Phase separated network
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