Domain: Natural Science — Chemistry
Target concept: The monomer isobutylene rapidly thickens after polymerization, quickly forming a white, fluffy solid polyisobutylene, with a fast reaction rate.

Video generation prompt: Under an inert atmosphere, a Lewis-acid initiator is added to isobutylene monomer in a sealed flask to initiate cationic polymerization, and the changes in the system are recorded.

Evaluation guide:
(i) Target concept: Rapid cationic polymerization of isobutylene, initiated by a Lewis-acid catalyst, yielding polyisobutylene as a white fluffy solid.
Minimum mechanism: Monomer must be pure and anhydrous; a Lewis-acid initiator (e.g. a catalyst solution injected into the flask) generates a carbocation on contact with the isobutylene; the inert atmosphere prevents termination by nucleophiles (e.g., water, oxygen); propagation is ultrafast because the methyl groups on isobutylene stabilize the growing carbocation.
(ii) Storyline: Frame 1: Static shot of a sealed flask holding colorless liquid isobutylene monomer, connected to an inert-gas line. Frame 2: A Lewis-acid catalyst is visibly introduced into the same flask (e.g., syringe injection or valve-controlled addition); this is the action that starts the reaction. Frame 3: Continuous emergence of a white, fluffy solid from within the liquid phase, expanding in volume, staying suspended, not settling. Perspective: Fixed frontal view, full vessel in frame, no occlusion of the interior. Visibility: the liquid must stay clear enough that the nucleation and growth of the solid inside the bulk is unambiguous.

Manual:
Experimental Procedure
1. A sealed flask containing colorless liquid isobutylene monomer is shown under inert atmosphere (gas inlet line attached).
2. A Lewis-acid catalyst solution is injected into the flask, initiating the reaction.
3. Within seconds, white fluffy solid polyisobutylene forms throughout the liquid.
Observation of Experimental Phenomena
Colorless liquid → rapid emergence of voluminous, suspended, white fluffy solid inside same vessel; no settling, no discoloration, no bubbling.
Summary of Experimental Principles
Isobutylene undergoes rapid cationic polymerization once a Lewis-acid initiator generates a carbocation on the monomer; the inert atmosphere keeps out water/oxygen that would quench the reaction, and the high reactivity of the resulting tertiary carbocation drives fast chain growth, yielding polyisobutylene — a white, fluffy solid.

Prompt Grounding rubric:
level_1: No inert-atmosphere setup is shown; no isobutylene monomer or its vessel appears; no catalyst-addition action is shown; there is no visual record of anything changing in the system.
level_2: Some equipment appears (e.g. a flask or a gas line) but it's the wrong kind (e.g. an open beaker instead of a sealed flask); the liquid monomer is never clearly shown inside the vessel; there's no sign of inert gas flow into the flask; no catalyst or initiator is ever added.
level_3: A sealed vessel, an inert-gas inlet line, and a colorless liquid identified as the isobutylene monomer are all visible together; a catalyst/initiator is then introduced into that same vessel (e.g. via syringe injection or valve); the vessel stays in frame and stationary throughout; the sequence shows the monomer present first, then the catalyst added.
level_4: Everything required at the 3-point level holds, and additionally: the inert-gas connection stays visibly attached to the flask with no exposure to open air; the catalyst-addition action is clearly linked to this same flask, in the same continuous shot (no cut to a different vessel); the flask contains only the liquid monomer right up until the catalyst is added.
level_5: Everything required at the 4-point level holds, and additionally: the catalyst is added only after the monomer is already shown in the flask, never before or simultaneously; the gas line stays visibly connected and unobstructed for the whole clip; no unrelated object (glove, label, extra tool) ever enters the frame or blocks the view of the flask.

Scientific and Causal Correctness rubric:
level_1: Nothing changes state: the liquid stays liquid the whole time; no solid ever appears; there's no visible link between adding the catalyst and any resulting change; what is shown doesn't look like fast cationic polymerization (e.g. only a slow drip, gradual clouding, or no visible reaction at all).
level_2: A solid appears but in the wrong form (e.g. it looks granular, crystalline, or sinks to the bottom instead of staying fluffy and suspended); its color is wrong (e.g. yellow or brown instead of white); the solid appears before the catalyst is added, or appears in a sudden jump-cut rather than growing continuously.
level_3: A white, fluffy solid appears only after the catalyst is added to the monomer; it forms inside the same liquid-filled flask; it looks voluminous and stays suspended in the liquid rather than settling; the liquid stays clear and colorless right up until the solid starts appearing; the solid's growth is continuous, with no sudden jump from empty liquid to a fully-formed mass.
level_4: Everything required at the 3-point level holds, and additionally: the solid appears once and doesn't flicker in and out; it keeps a fluffy texture throughout (not compact, stringy, or film-like); the liquid doesn't discolor before or during solid formation; nothing else happens that wouldn't fit fast cationic polymerization (no boiling, no fuming, no unrelated color shift).
level_5: Everything required at the 4-point level holds, and additionally: the solid clearly originates from within the bulk liquid, not just at the surface or against the flask wall; its visible volume keeps increasing continuously from first appearance to the end of the clip; nothing is mistaken for solid that isn't (no bubbles, condensation, or reflections read as solid); the fluffy texture looks uniform across the whole visible mass.

Spatiotemporal Consistency rubric:
level_1: The flask suddenly appears in a different spot or the shot cuts to a mismatched background; the room's lighting changes drastically with no visible cause; the white solid appears with no liquid ever having been shown first; the flask's shape distorts between frames (e.g. it looks like a different container).
level_2: The liquid's fill level looks different before and after a cut with no visible reason; the direction of the light source (and its shadow) shifts between shots; the solid appears abruptly with no sense of growth or spreading over time; the camera zooms or pans in a way that disconnects the gas-inlet line from the flask visually.
level_3: The camera holds one fixed viewpoint; the flask stays fully in frame and doesn't shift position or tilt; the liquid surface stays level and steady; the solid's growth is visible frame to frame within the same region of the flask; nothing in the scene abruptly disappears or reappears; the lighting doesn't flicker and the shadow doesn't suddenly jump.
level_4: Everything required at the 3-point level holds, and additionally: the gas-inlet line stays attached at the same point on the flask in every frame; the liquid's meniscus and its reflections stay stable; the solid's growth follows gravity in a consistent direction (it doesn't appear to float free of the liquid); objects that should be behind or in front of others keep that same order throughout.
level_5: Everything required at the 4-point level holds, and additionally: the growing solid's motion looks smooth from frame to frame, with no stutter, freeze, or obvious jump; the flask walls don't flex, warp, or show unnatural refraction as the solid expands; reflections and highlights on the flask stay physically plausible and consistent over time.