Instead of rendering a 3D lattice of chains, this version tracks a large statistical ensemble of 400 polymer chains as pure bond-state arrays and displays three 2D-native views of the same random-scission process: a bond-state matrix (one row per chain, one column per ester bond — green = intact, orange fading to dark = recently/long-since cleaved), a live fragment-length histogram (the emerging Flory-type distribution of surviving oligomer lengths), and a Mn / mass strip chart plotting both quantities against elapsed time.
Each intact ester bond has a constant per-step probability of cleaving — first-order kinetics, exactly like radioactive decay:
dN/dt = −k(t)·N
N(t) = N₀ · e^(−∫k dt)
Number-average degree of polymerization Xn follows from the fraction of bonds broken p(t):
Xn(t) = Xn(0) / (1 + Xn(0)·p(t))
Mn(t) ∝ Xn(t)
Mass loss lags Mn decay: a chain cut in half is still two solid fragments. Only fragments at or below a short oligomer threshold are counted as dissolved, reproducing the delayed, then steep, PLA/PGA "bulk erosion" mass-loss curve.
Autocatalysis: acidic end-groups created by scission accelerate nearby hydrolysis, scaling the effective rate constant by the ensemble-wide fraction already broken — the same self-catalyzed acceleration seen in thick PLGA implants.
- Rate constant k — baseline per-step hydrolysis probability per intact bond.
- Autocatalysis strength — how much accumulated scission accelerates further scission.
- Chain length — initial monomers per chain, i.e. initial DP, Xn(0).