Multimolecular vs. Macromolecular Colloids: Key Differences Explained
Multimolecular colloids are clusters of many small molecules (e.g., gold nanoparticles) held by weak forces. Macromolecular colloids are single giant molecules (e.g., starch, proteins) dispersed in solvent, each particle being the macromolecule itself.
Home cooks see cornstarch thicken soup and assume it’s “particles.” Chemists know it’s actually long starch chains—macromolecules—while the cloudiness in gold-ruby glass is millions of tiny gold atoms teaming up, a multimolecular dance. The confusion? Both look cloudy, yet one is many, one is huge.
Key Differences
Multimolecular colloids form from small units aggregating; particle size ~1–100 nm, reversible. Macromolecular colloids are already large single molecules; size 1–1000 nm, irreversible. Stability relies on charge vs. solvation.
Which One Should You Choose?
Pick multimolecular colloids for sensors (gold sols) needing tunable color. Choose macromolecular colloids for drug delivery (dextran) needing biocompatibility and controlled viscosity.
Examples and Daily Life
Fog (water droplets) = multimolecular; gelatin dessert = macromolecular. Both scatter light, yet one melts on reheating, the other stays intact.
Can you filter them?
Neither passes ordinary filter paper, but ultrafiltration separates macromolecular colloids by size.
Are they toxic?
Gold multimolecular colloids are inert; some synthetic macromolecular carriers need safety testing.