Several synthetic strategies based on the use of substituted aromatic and hetero-aromatic thiols for the covalent binding of modifier compounds to PVC are described. A variety of aliphatic alcohols and amines are linked to the aromatic or heteroaromatic rings via highly active functionalities as the isocyanate, acidchloride, or chlorosulfonyl group, and the three chlorine atoms of trichlorotriazine. The first three pathways lead to protected aromatic disulfides obtaining the substituted aromatic thiols by reduction as a final step of an unprecedented synthetic route. The second approach, in a novel, extremely efficient, and scalable process, uses the particular selectivity of trichlorotriazine to connect aliphatic amines, alcohols, and thiols to the ring and creates the thiol via nucleophilic substitution of a heteroaromatic halogen by thiourea and subsequent hydrolysis. Most of the modifier compounds were linked to the polymer chains with high degrees of anchorage. The presented approaches are highly versatile as different activations of aromatic and heteroaromatic rings are used. Therefore, many types of tailored functional nucleophiles may be anchored to PVC providing non-migrating materials with a broad range of applications and properties.

We have investigated the ring-opening polymerization (ROP) of ε-caprolactone using mixtures of methanesulfonic acid and the guanidine 1,5,7-triazabicyclo[4.4.0]dec-5-ene as the catalyst. Our interest in these mixtures is based on the capability of both acids and bases to behave as bifunctional catalysts; the former by the combined action of acidic hydrogens and basic oxygens, and the latter by the hydrogen-bond acceptor and donor features of, respectively, a basic nitrogen center and an ortho-hydrogen atom. We found that these compounds are capable of forming eutectic mixtures at a certain molar ratio. Upon the use of these mixtures – e.g. with molar ratios near to the eutectic one – as catalysts, neither further solvents nor initiators were required to carry out the ROP of ε-caprolactone. The resulting polycaprolactones (PCLs) were highly crystalline (more than 87%) and exhibited an excellent capability to support the growth of murine L929 fibroblasts. We consider that the preparation of biocompatible PCLs at physiological temperatures and in the absence of reagents other than the monomer and the catalyst offers an interesting alternative to both the self-cross-linked oligomers/macromers of acrylate-based PCL-derivatives and the pH/temperature-sensitive PCL copolymers used to date as injectable biomaterials.