In this study, stannous octoate (Sn(Oct)2) as catalyst, methoxy polyethylene glycol or polyethylene glycol as co-catalyst to ring-opening lactide (LA) and glycolide (GA) to synthesize a series of non-toxic, non-solvent, and injectable thermosensitive methoxy polyethylene glycol (mPEG) and poly(lactide-co-glycolide) di-block copolymer (mPEG-PLGA), then this copolymer was end-blocked with 2, 2-bis (2-oxazoline) (Box). The effect of the Box structure in the di-block copolymer on the lower critical transition temperature (LCST), gel stability, phase transition temperature, and cell cytotoxicity of the copolymer was investigated in this study. The results showed that the copolymer’s LCST increased and their critical gelation concentrations (cgc) reduced when the copolymer dissolved in different solutes for the copolymer chain en-capped with Box. The range of gel formation temperature increase when they dissolved in different solutions, such as saline, Bovine Serum Albumin (BSA), or glucose (10 wt%), but their degradation rate would slow down. The stability of storage of the copolymers in different temperatures was measured, in which the commercial products, Macro Med, was referred as its product shelf life duration 18 months when storage in -20 oC of temperature.
This research is focus on synthesis of the shape-memory materials based on [polyethylene glycol (PEG) / polycaprolactone (PCL)]-polyurethane (PU) which is biodegradable. Because biodegradable PCL is hydrophobic when we use it as a soft-chain, then combine it with a hard-chain PU which is made from 2, 4-toluene diisocyanate (TDI) and chain-extend agent to synthesize a shape-memory polyurethane, the products will also exhibit hydrophobic. In this article, , we try to change the molecular weight of PEG in the polyethylene glycol (PEG) / polycaprolactone (PCL) to improve the their hydrophilicity and let the products become more biocompatible. Besides, we also compared the properties of polyurethane by changing the composition of soft-chain and hard-chain. The structure and properties and molecular weight of the copolymers were measured with FT-IR, DSC, and GPC. The results showed that when the composition of hard-chain increases, the crystallinity of PCL will decrease because of the physical-crosslink formed by hard-chain in the structure, and then the melting point will be decreased. In addition, the water contact angles of the [(PEG-PCL)-PU] di-block copolymers decrease with increase of the hydrophilic PEG. PCE20 series copolymers have better shape-memory recovered ratio because the amount of hard-chain can effectively form enough physical-crosslink.