Method for preparing polylactone by ring opening

#The present invention belongs to the technical fields of organic catalysis and high polymer materials, and particularly relates to a method for preparing polylactones by ring opening catalysis using a pyridinium salt.

#Polylactones are currently marketed as bio-based degradable materials, and have important application values in industrial production fields such as biodegradable plastics and medical fields such as surgical sutures, drug controlled release carriers, dental bone materials and the like due to the advantages of being recyclable and degradable, saving water, energy and raw material consumptions, reducing waste discharge and the like.

#As for polylactic acid, two polymerization methods of direct polycondensation of lactic acid and ring opening polymerization of lactide are mainly used at present. In the process of synthesizing polyester by direct polycondensation of lactic acid, trace moisture in the reaction product is difficult to remove, resulting in a generally not high average relative molecular weight, and therefore limited in many applications. The ring opening polymerization of lactide is mainly catalyzed by metals in the past studies, but in recent years, the drawbacks brought by the use of metals as catalysts in the preparation of aliphatic polyesters are gradually exposed, and the development of polylactic acid in the fields of biomedicine and microelectronics is limited due to the metal residues in the products. Therefore, in recent years, many scholars have gradually turned the research goal to organic catalysis. DMAP is the first organic catalyst used in the polymer synthesis. Connor etc. (Fredrik Nederberg et al. Angewanfefte Chemie International Edition, 2001, 40, 2712-2715) reported the first achievement of an organocatalysis living polymerization under conditions of ethanol, isopropanol or benzyl alcohol as an initiator and DMAP or PPY as a catalyst to give a polylactic acid product with controllable activity and narrow molecular weight distribution.

#Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which:

#FIG. 1: 1H NMR of polylactic acid prepared with 4-(N, N-dimethylamino) pyridine hydrochloride catalyst;

#FIG. 2: 1H NMR of polytrimethylene carbonate prepared with 4-(N, N-dimethylamino) pyridine hydrochloride catalyst; and

#The invention is further illustrated by the following examples, which are intended to illustrate and not to limit the invention. Those skilled in the art will appreciate that the embodiments do not limit the invention in any way, and that suitable modifications and data changes may be made thereto without departing from the spirit and scope of the invention.

#The structures of catalysts used in the examples are shown in the following table:

#No. Structure 16 3 5 7 12 14 10