Radiation‐induced graft polymerization of styrene onto poly(3‐hydroxybutyrate) and its copolymer with 3‐hydroxyvalerate

Abstract

Graft copolymerization of styrene (St) onto poly(3-hydroxybutyrate) (PHB) andpoly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(HB-HV)) was carried out using simultaneous irradiation and pre-irradiation techniques with 6oCo y-rays. The degree of grafting (X,) of styrene onto PHB increased with increasing pre-irradiation dose and grafting temperature while in the graft reaction of the copolymer, X, was higher at 50°C than at 70°C. This X, was lower than that in grafting methyl methacrylate (MMA) onto PHB and its copolymer. In the electron spin resonance (ESR) study, the PHB radical formed by irradiation was converted to a propagating radical by introducing St monomer at room temperature (25 "C) for grafting. The propagating radical was observed even at 50°C and 70"C, grafting of St onto PHB occurs actively at such temperatures. The decay of the radical concentration during grafting well corresponded to radical consumption in graft polymerization. The molecular weight (Mn) depended on the grafting conditions and the increase of the grafting temperature induced the formation of reduced M, because of early termination. It was confirmed that the increase of X, in pre-irradiation of more than 10 kGy was due to the increment of the graft chain. ZUS AMMENFASSUNG: Die Pfropfcopolymerisation von Styrol (St) auf Poly(3-hydroxybutyrat) (PHB) und auf dessen Copolymeres Poly(3-hydroxybutyrat-co-3-hydroxyvalerat) (P(HB-HV)) wurde unter gleichzeitiger Anwendung von Bestrahlungs-und Vorbestrahlungstechniken mit 60Co-y-Strahlung durchgefuhrt. Der Pfropfungsgrad (X,) von Styrol auf PHB erhohte sich mit zunehmender Vorbestrahlungsdosis und Pfropfungstemperatur. Dagegen lag der Pfropfungsgrad des Copolymeren bei 50 "C hoher als bei 70°C. Verglichen mit der Pfropfung von Methylmethacrylat auf PHB und dessen Copolymeres wurden mit Styrol geringere Pfropfungsgrade erzielt. ESR-Untersu-

Synthetic routes to degradable copolymers deriving from the biosynthesized polyhydroxyalkanoates: A mini review

“…This conjugate could be used as biodegradable controlled-release systems of pesticides with potentially higher resistance to weather conditions in comparison to conventional forms of pesticides [124]. If a nucleophile (monomethoxy PEG, mPEG) empolyed in the trans- [134,135] esterification under bis(2-ethylhexanoate) tin (catalyst), a PHB-b-mPEG copolymer was formed (Figure 7). The diblock copolymers were amphiphilic and could be self-assembled into sterically stabilized colloidal suspensions of PHB crystalline lamellae.…”

“…The #-radiation grafting polymerization could be done at the ambient temperature without any initiator. Vinyl monomers, such as methyl methacrylate or 2-hydroxyethyl methacrylate [132,133], styrene [134,135], isoprene [136], acrylic acid [137], and maleic anhydride [138] have been reported to be grafted onto PHB or PHBV with a high yield (up to 80%).…”

A Novel Characterization Method for Graft‐Polymer Structures Chemically Attached on Thermally Stable Polymer Films

“…Water was from a Millipore Milli-Q UV system, consisting of a UV lamp and multiple microporous fi lters to give a resistance of > 18.2 M Ω cm and a total organic carbon content of < 10 ppb. NMR ( 1 H, 13 C, 19 F and distortionless enhancement by polarization transfer (DEPT)) spectra were recorded using a Bruker AV 300 MHz spectrometer at room temperature, using deuterium oxide (D 2 O) as the solvent. The chemical shifts are reported in ppm relative to sodium 2,2-dimethyl-2-silapentane-5-sulfonate (DSS) (Aldrich) as the standard.…”

“…[ 2 , 3 , 6-16 ] The analysis of the chemical structures and molecular weights of the grafts in grafted fi lms prepared by radiationinduced graft polymerization and the subsequent solidstate chemical transformations is restricted to degradable or soluble polymer substrates, such as poly(ethylene oxide), poly(butylene oxide) and natural polymers. [17][18][19] However, grafts introduced into practical polymer substrates are generally thermally and chemically stable, and, thus, cannot be isolated from the substrates for detailed analysis. Recently, we found that the poly(styrenesulfonic acid) (PSSA) grafts in fl uorinated polymer substrates can be successfully isolated in water at 85 ° C by the swellinginduced detachment of the hydrophilic grafts from the hydrophobic polymer substrates without decomposition of the side chains and main chains (thus maintaining the molecular weights).…”

Surface modification of biodegradable poly (butylene succinate) by gas PIII

“…1. It possesses good processability, superior mechanical properties, harmless degradation products (CO 2 and H 2 O), and adjustable degradation rate [1][2][3], which are promising for bone and cartilage repair.…”