Guan-ying Wu

SYNTHESIS OF POLYISOBUTYLENE WITH SEC-ARYLAMINO TERMINAL GROUP BY COMBINATION OF CATIONIC POLYMERIZATION WITH ALKYLATION

The highly reactive polyisobutylenes (PIBs) with α-double bonds (87.5 mol%) or tert-chloro (tert-Cl) groups (95 mol%) could be prepared via the cationic polymerization of isobutylene (IB) coinitiated by BF3 or TiCl4 respectively. The Friedel-Crafts alkylation of diphenylamine (DPA) with the highly reactive PIB with α-double bonds was further conducted under different conditions, such as at different alkylation temperature, in the mixed solvents of CH2Cl2/n-hexane with different solvent polarity and at DPA concentration ([DPA]). The resultant PIBs with sec-arylamino terminal groups were characterized by GPC with RI/UV dual detectors and 1H-NMR spectrum. The experimental results indicated that alkylation efficiency increased with increases in reaction temperature, solvent polarity and [DPA]. The 77 mol% of sec-arylamino terminated PIBs could be obtained in 10/90 (V/V) mixture of nHex/CH2Cl2 with [DPA]/[PIB] of 3.0 at 60°C for 45 h. Moreover, the alkylation of DPA with highly reactive PIBs with mainly tert-C...

SYNTHESIS AND CHARACTERIZATION OF POLY(L-GLUTAMIC ACID-co-L-ASPARTIC ACID)

Poly(amino acid) has been widely utilized in drug delivery, tissue engineering and biomedical materials. The biomaterials based on poly(glutamic acid) are usually modified via copolymerization with other monomers such as L-aspartic acid to improve the uncontrolled degradation rate. The ring-opening homo- and co-polymerization of γ-benzyl-L-glutamate N-carboxyanhydride (BLG-NCA) and β-benzyl-L-aspartate N-carboxyanhydride (BLA-NCA) were carried out in solution by using triethylamine (TEA) as initiator. The BLG-NCA homopolymerization could take place even at -30°C and molecular weight of poly(γ-benzyl-L-glutamate) decreased with increasing polymerization temperature. The BLA-NCA polymerization did not occur at -10°C and was needed to be carried out at 25°C to improve the polymerization. Poly(γ-benzyl-L-glutamate) and poly(β-benzyl-L-aspartate) with unimodal molecular weigh distribution and weight average molecular weight (Mw) of 32100 and 4000 could be obtained at 25°C. The copolymers of γ-benzyl L-glutamate and β-benzyl L-aspartate with unimodal molecular weight distribution and Mw ranging from 5600 to 24600 could be prepared. The useful copolymers of poly(L-glutamic acid-co-L-aspartic acid) were further prepared by removal of benzyl groups.