End-group effect on chain conformation of poly(propylene glycol) and poly(ethylene glycol)

✍ Scribed by Sunghoe Yoon; William J. MacKnight; Shaw Ling Hsu

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 138 KB
• Volume: 64
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19970404)64:1<197::aid-app18>3.0.co;2-1

✦ Synopsis

A comparison is made of the chain conformational distribution of hydroxyterminated poly(propylene glycol) (PPG) and poly(ethylene glycol) (PEG) with their methoxy-terminated derivatives. The significant end-group dependence on the glass transition temperature in PPG was observed by differential scanning calorimetry. Raman active skeletal vibrations in the low-frequency region indicated a significant difference in chain conformation distribution between methoxy-and hydroxy-terminated PPGs, yet almost no difference between MPEG and HPEG. The increased chain stiffness in HPPG in comparison to MPPG has been attributed to the hydrogen-bonding interaction associated with the hydroxy end group in HPPG. Furthermore, the structural differences observed between PPG and PEG have been attributed to the differences in the interaction of the hydroxy end group to the ether oxygen in the two polymers. The interaction between the hydroxy end group and ether oxygen differs because the {CH 3 side group is present for one and not for the other. These structural differences are reflected in the glass transitions temperatures measured.