Synthesis, Properties, and Enzymatic Hydrolysis of Poly(lactic acid)-co-Poly(propylene adipate) Block Copolymers Prepared by Reactive Extrusion

Abstract

Poly(lactic acid) (PLA) is a biobased polyester with ever-growing applications in the fields of packaging and medicine. Despite its popularity, it suffers from inherent brittleness, a very slow degradation rate and a high production cost. To tune the properties of PLA, block copolymers with poly(propylene adipate) (PPAd) prepolymer were prepared by polymerizing L-lactide and PPAd oligomers via reactive extrusion (REX) in a torque rheometer. The effect of reaction temperature and composition on the molecular weight, chemical structure, and physicochemical properties of the copolymers was studied. The introduction of PPAd successfully increased the elongation and the biodegradation rate of PLA. REX is an efficient and economical alternative method for the fast and continuous synthesis of PLA-based copolymers with tunable properties.

Direct and indirect effects on molecular mobility in renewable polylactide–poly(propylene adipate) block copolymers as studied via dielectric spectroscopy and calorimetry

“…More direct evidence on this interaction can be seen from infrared spectroscopy data shown in a recent work. 46 These results have been adapted and included in Fig. 6b as an inset.…”

“…Despite the said interactions, it is expected that there are still many free end-groups (hydroxyls and carboxyls), as in a previous study, the hydrophilicity of the copolymers was found to increase with PPAd (lowering of M n ) and, subsequently, so did the enzymatic hydrolysis. 46 The focus in now turned onto segmental dynamics. In neat PLA, a PLA is recorded and fitted well by an asymmetric HN term with a HN B 0.6 and b HN B 0.6.…”

“…[49][50][51][52][53] Compared to PLA, poly-(n-alkylene adipate)s demonstrate much easier chain diffusion, equivalently, lower glass transition temperatures (between -63 and -45 1C). 34,46,[48][49][50][51] Thus, PnAAds may act as plasticizers for PLA and, simultaneously, as additional compounds that favor manipulation of crystallization. 34,44 A recently synthesized series of block copolymers based on PLA and poly(propylene adipate), PPAd, 46 are investigated in the present work.…”

“…34,46,[48][49][50][51] Thus, PnAAds may act as plasticizers for PLA and, simultaneously, as additional compounds that favor manipulation of crystallization. 34,44 A recently synthesized series of block copolymers based on PLA and poly(propylene adipate), PPAd, 46 are investigated in the present work. The emphasis is on the direct effects of copolymer composition and chain length on the local and segmental molecular mobility.…”

Single-Chain Mechanical Properties of Gelatin: A Single-Molecule Study

“…The nonrenewable and nondegradable properties of resources such as coal, oil and natural gas have a huge impact on the environment. As the only renewable carbon source, biomass resources have attracted a large amount of attention due to their biodegradability, recyclability and environmental friendliness, and are an important way to obtain many biomass chemicals [ 4 , 5 , 6 , 7 , 8 , 9 ]. Gelatin is a natural water-soluble biodegradable polymer material.…”