Synthesis, structure and thermal properties of poly(A-block-B-block-A) copolymer based on biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and amorphous polystyrene

Abstract

A series of poly(A-block-B-block-A) copolymers based on biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and amorphous polystyrene (PS) were synthesised by atom transfer radical polymerisation (ATRP). The chemical structure, molecular weight and distribution were systematically characterised by Fourier transform infrared, 1 H nuclear magnetic resonance ( 1 H NMR) and gel permeation chromatography (GPC). The melting and crystallisation behaviours, and thermal stabilities of copolymers were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA); the degradation activation energy was calculated by Horowitz-Metzger method. Results showed that the maximum yield of triblock copolymer was 88%. DSC curves revealed that the triblock copolymers had their cold crystallisation temperature from 50?83 to 65?67uC, and the crystallinity from 55?60 to 12?60. TG curves showed that the thermal stabilities of triblock copolymers were enhanced, and its degradation activation energy decreased from 428 to 197 kJ mol 21 .

Modification and Potential Application of Short-Chain-Length Polyhydroxyalkanoate (SCL-PHA)

“…Zhu et al studied the influence of molecular structure on the crystallization behavior and thermal stability of PHBHV in an effort to obtain a copolymer with high thermal stability and mechanical properties. A series of crystalline/amorphous copolymers were designed by chemical block copolymerization, including PMMA- b -PHBHV [ 100 ] and PS- b -PHBHV [ 101 ] triblock copolymers. They found that the cold crystallization temperature of both PMMA- b -PHBHV and PS- b -PHBHV were shifted to a higher temperature with the increasing content of amorphous component, and for PMMA- b -PHBHV the increased value was up to 60 °C.…”

“…The graft ratio of MA on the P3HB macromolecule chains increased from 0.2 to 0.9 wt % and the degradation temperature ( T d -5% ) of P3HB increased by 35 °C [ 110 ]. The thermal stability of PS- b -PHBHV triblock copolymers was analyzed by TGA and results showed that the T d -5% and T max of triblock copolymers increased by 30 and 40 °C compared with those of PHBHV, respectively [ 101 ]. Park et al found that the thermal stability of P3HB was improved by the crosslinking reaction between the epoxy group and terminal carboxyl group in polyglycidyl methacrylate (PGMA) [ 111 ].…”

Synthesis and thermal decomposition kinetics of poly(methyl methacrylate)-b-poly(styrene) block copolymers

“…Therefore, T d, max increases with the increase of the PS segments, which means that the improvement of thermal stability is mainly attributed to the introduction of rigid PS segments into polymer backbone. 34,35…”

“…Therefore, T d, max increases with the increase of the PS segments, which means that the improvement of thermal stability is mainly attributed to the introduction of rigid PS segments into polymer backbone. 34,35 On the basis of the above analysis, pyrolysis process of all polymers can be divided into two stages. The first stage has maximum decomposition temperature T 1 ranging from 200 C to 340 C, during which the mass loss of copolymer is not significant, and the mass loss of PMMA-b-1PS is 3% (14% to 17%) and PMMA-b-1.8PS is about 8% (5% to 13%), while the PMMA initiator is about 9% (22% to 31%).…”