When poly (lactic acid-co-melamine) [P(LA-co-MA)] is synthesized via direct melt polycondensation (DMP), with the more MA in the feed content, the copolymer with a three-MA-core structure linked by the ether bond is formed. Increasing the molar feed ration(LA)/n(MA), the structure of the copolymers is gradually changed from multi-core structure into SPLA structure only containing one MA core, and a peak value of Mwexists as expected. The aromatic cores with different functional groups have an important influence on the Mwpeak value, and the internal factors are the conjugate effect and the nucleophilicity caused by the different functional groups themselves.
Directly starting fromD,L-lactic acid (LA) and melamine (MA), novel star-shaped biodegradable material poly (lactic acid-co-melamine) [P(LA-co-MA)] as a kind of potential flame retardant is synthesized via melt polycondensation. When the molar feed ration(LA)/n(MA) is 60/1, the optimal synthetic conditions are discussed. After the prepolymerization at 140 °C for 8 h, using 0.4wt% stannous chloride as the catalyst, the melt copolymerization at 160 °C for 8 h gives the copolymer with the biggest intrinsic viscosity 0.87 dLg-1.
Using 1,3,5-benzenetrioxyundecanol (mTU) as the core, and more cheaper D,L-lactic acid (D,L-LA) as starting material, a novel star-shaped poly(D,L-lactic acid) (SPDLLA) was synthesized via direct melt polycondensation with simple process and low-cost. The obtained biodegradable polymer SPDLLA was systematically characterized with the intrinsic viscosity [η], FTIR, 1H-NMR, GPC and XRD. The Tg and crystallinity of all SPDLLA were much lower than that of the linear poly(D,L-lactic acid). When n(D,L-LA) : n(mTU) was 120 : 1, the biggest Mw was 10800, which was bigger than that obtained from L-lactic acid (L-LA). All Mw meet the requirement for drug delivery application.
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