Synthesis and characterization of polypropylene‐<i>graft</i>‐poly(<scp>l</scp>‐lactide) copolymers by CuAAC click chemistry

Abstract

ABSTRACT The syntheses of polypropylene‐ graft ‐poly( l ‐lactide) copolymers (PP‐ g ‐PLAs) via copper (I)‐catalyzed azide‐alkyne cycloaddition “click” reaction (CuAAC) using azide side‐chain functionalized polypropylene (PP‐N 3 ) and alkyne end‐functionalized poly( l ‐lactide) (PLA‐Alkyne) were reported. The CuAAC was then applied to azide and different feeding ratios of alkyne functional polymers to give PP‐ g ‐PLAs that were characterized by FTIR, 1 H‐NMR, GPC, DSC, and WCA measurements. The CuAAC click reaction was achieved by two different feeding ratio (PP‐N 3 :PLA‐Alkyne = 1:5 and 1:10) and thermal, biodegradable, and surface properties of obtained graft copolymers were investigated. The molar ratio of PLA were calculated as 72.7 (PP‐ g ‐PLA‐1) and 78.4% (PP‐ g ‐PLA‐2) by 1 H‐NMR spectroscopy. The water contact angle (WCA) values of PP‐ g ‐PLA‐1 (81 o ± 1.3) and PP‐ g ‐PLA‐2 (75 o ± 1.6) copolymers were compared with commercial chlorinated polypropylene (PP‐Cl) (90 o ± 1.0), suggesting a more hydrophilic nature of desired graft copolymers produced. Conversely, the enzymatic biodegradation studies revealed that the weight losses of graft copolymers were determined as 13.6 and 22.1%, which is about 4% for commercial PP‐Cl sample. Thus, it was clear that this simple and facile method was effective in promoting biodegradation of commercial polypropylene and attractive particularly for worldwide environmental remediation goals. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2595–2601