SYNTHESIS OF DEGRADABLE CROSS-LINKED POLYMERS BASED ON 1,5-DIOXEPAN-2-ONE AND CROSS-LINKER OF BIS-EPSILON-CAPROLACTONE TYPE

Poly(lactones) may be crosslinked by ring-opening polymerization of th e corresponding cyclic esters in the presence of tetrafunctional bis(e psilon-caprolactone). The homopolymer of 1.5-dioxepan-2-one (DXO) has poor mechanical properties but also some very goad properties, such as biocompatibility and degradability. Crosslinking of degradable polyme r based on the poly(ether-ester) DXO was performed with crosslinkers h aving the same reactivity as the monomer. 2,2-Bis(epsilon-caprolactone -4-yl)propane (BCP) and bis(epsilon-caprolactone-4-yl) (BCY) with tetr afunctionalities were synthesized from the corresponding diols and the n used as comonomers during the polymerization of DXO. The comonomers showed the same reactivity to the initiator, stanneous 2-ethylhexanoic acid, as DXO and perfectly random crosslinked films were obtained. Th e crosslinked films showed a high degree of swelling already at 2-3 mo l % BCP or BCY. The BCP crosslinker was somewhat less soluble in DXO a t lower temperatures, but all BCP was soluble at 180 degrees C. These polymeric films were elastic with no crystallinity and the T-g values increased from -39 degrees C for pure DXO to -35 degrees C for BCP cro sslinked films and -21 degrees C for BCY crosslinked ones. (C) 1997 Jo hn Wiley & Sons, Inc.