Description of collagen fibril formation by a theory of polymer crystallization

A well‐known nucleation‐growth model, used extensively to describe the crystallization of synthetic polymers, has been applied to collagen. The model gives (1) a general representation of the effect of temperature on the rate of collagen fibril formation, (2) a semi‐quantitative description of the effect of collagen concentration on growth rate, and (3) an estimate of fibril diameter that is in agreement with observations made by electron microscopy. The mechanism described is apparently that of the early stages of fibril growth, in which microfibrils are formed. An important parameter required in this approach is the free energy of fibril formation. The free energy was approximated by use of an expression derived by Flory for rodlike polymers. Flory's equation plus experimental data on collagen solubility permitted calculation of the free energy over a range of temperature. The resultant expression was of the same form as one commonly used in describing crystallization of synthetic polymers.