کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5204759 1381970 2007 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Bacterial polyesters grafted with poly(ethylene glycol): Behaviour in aqueous media
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Bacterial polyesters grafted with poly(ethylene glycol): Behaviour in aqueous media
چکیده انگلیسی

An easy method for grafting of poly(3-hydroxyoctanoate-co-3-hydroxyundecenoate) (PHOU) was developed. Oxidation of the pendant double bonds of PHOU into carboxyl groups to yield poly(3-hydroxyoctanoate-co-3-hydroxy-9-carboxydecanoate) (PHOD) and the esterification of the carboxyl side groups with poly(ethylene glycol) (PEG) were carried out in a single reaction solution. The grafting yield is dependent on the molar mass of the PEG graft. The maximum carboxyl group conversion (52%) was obtained with PEG Mn = 350 and decreased with increasing molar mass of PEG (19% for PEG Mn = 2000). Yields were determined by 1H and 13C NMR. Short PEG grafts lowered the glass transition temperature (PHOD-g-PEG 350 −57 °C) compared to PHOD (−19 °C) and PHOU (−39 °C). This effect depends on the COOH conversion and PEG chain length. Grafting enhanced the hydrophilic character of the modified polymers making them soluble in polar solvents, such as alcohols and water/acetone mixtures. PHOD-g-PEG films were more stable towards hydrolytic degradation as PHOD films. No obvious modification of films was observed after more than 200 days at pH 7.2 and 37 °C. The molar mass of the grafted polymers decreased only slightly during this period, while PHOD films were hydrolyzed into soluble fragments.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer Degradation and Stability - Volume 92, Issue 7, July 2007, Pages 1384-1392
نویسندگان
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