The Binding of Preformed Polymers to Hair

The work of Steinhardt and Harris and the affinities of organic acids [14] and quaternary ammonium hydroxide compounds [15] to keratin illustrate the importance of increasing molecular size and even nonprimary bonds to the substantivity of ingredients to hair. In the case of polymeric ingredients, 

It is convenient to consider three extreme types of bonds between polymer and hair  

Primary valence bonds (ionic and covalent bonds) 

Note that bond classifications of this type are not rigorous the transition from one type to another is gradual. Therefore, intermediate bond types do exist [16], although for simplicity in the following discussion a rigorous classification of bond type is presented. 

Primary valence bonds include ionic and covalent bonds and are the strongest binding forces. They generally have bond energies of approximately 50 to 200kcal/mole [17]. Ionic bonds are extremely important to the interactions of polymeric cationic ingredients and hair, whereas covalent bonds are probably involved between polymer and hair in certain in situ polymerization reactions or in the reaction of oxidation dyes with hair. 

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