Shear induced crystallization of poly(L-lactide) and poly(ethylene glycol) (PLLA-PEG-PLLA) copolymers with different block length

2010 ◽  
Vol 18 (4) ◽  
pp. 675-680 ◽  
Author(s):  
Xiao Hu ◽  
Jia-Zhuang Xu ◽  
Gan-Ji Zhong ◽  
Xiang-Lin Luo ◽  
Zhong-Ming Li
e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Nongnit Morakot ◽  
Jirasak Threeprom ◽  
Yodthong Baimark

AbstractBiodegradable films of methoxy poly(ethylene glycol)-b-poly(DL-lactideco- glycolide-co-ε-caprolactone) diblock copolymers (MPEG-b-PDLLGCL) were prepared by solution casting method. Effects of MPEG block length and DLL:G:CL ratio of the MPEG-b-PDLLGCL films on their mechanical properties and hydrolytic degradation were studied and discussed. It was found that the mechanical properties of films were strongly dependent on glass transition temperatures (Tg) of the diblock copolymers. The hydrolytic degradation was investigated in phosphatebuffered solution at 37°C. The degraded films were characterized using gravimetry (%water uptake and %weight loss), 1H-NMR spectroscopy, differential scanning calorimetry and size exclusion chromatography. The %weight loss of the degraded films increased and molecular weight decreased on increasing the MPEG block length and incorporating the G and CL units, according to their %water uptakes. The MPEG content of the degraded film decreased and the Tg increased with hydrolytic degradation time.


2019 ◽  
Vol 52 (2) ◽  
pp. 142-158 ◽  
Author(s):  
Yodthong Baimark ◽  
Yaowalak Srisuwan

The brittleness of poly(L-lactide) (PLLA) bioplastic is the main disadvantage for practical applications. Herein, we report the synthesis of high-molecular-weight PLLA- b-poly(ethylene glycol)- b-PLLA (PLLA-PEG-PLLA) block copolymers by ring-opening polymerization of LLA. The highly flexible PLLA-PEG-PLLAs were prepared by reactive melt blending with an epoxy-based chain extender formed as long-chain branched structures. The effects of PEG block length and content of chain extender were investigated. The results showed that the chain extension reaction reduced crystallinities of the PLLA-PEG-PLLAs. All the chain-extended PLLA-PEG-PLLA films had no phase separation. The lower crystallinities of PLLA-PEG-PLLA films obtained with higher contents of chain extender enhanced the film drawability. The longer PEG block length resulted in higher strain at break and lower stress at the break of PLLA-PEG-PLLA films. These chain-extended PLLA-PEG-PLLAs have potential for use as highly flexible bioplastics.


2013 ◽  
Vol 48 (20) ◽  
pp. 7055-7062 ◽  
Author(s):  
Solmaz Bayati ◽  
Ramón Pamies ◽  
Sondre Volden ◽  
Kaizheng Zhu ◽  
Anna-Lena Kjøniksen ◽  
...  

2010 ◽  
Vol 20 (17) ◽  
pp. 3416 ◽  
Author(s):  
Yun Young Choi ◽  
Ji Hye Jang ◽  
Min Hee Park ◽  
Bo Gyu Choi ◽  
Bo Chi ◽  
...  

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 602
Author(s):  
Yulia A. Kadina ◽  
Ekaterina V. Razuvaeva ◽  
Dmitry R. Streltsov ◽  
Nikita G. Sedush ◽  
Eleonora V. Shtykova ◽  
...  

Nanoparticles based on biocompatible methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (mPEG113-b-P(D,L)LAn) copolymers as potential vehicles for the anticancer agent oxaliplatin were prepared by a nanoprecipitation technique. It was demonstrated that an increase in the hydrophobic PLA block length from 62 to 173 monomer units leads to an increase of the size of nanoparticles from 32 to 56 nm. Small-angle X-ray scattering studies confirmed the “core-corona” structure of mPEG113-b-P(D,L)LAn nanoparticles and oxaliplatin loading. It was suggested that hydrophilic oxaliplatin is adsorbed on the core-corona interface of the nanoparticles during the nanoprecipitation process. The oxaliplatin loading content decreased from 3.8 to 1.5% wt./wt. (with initial loading of 5% wt./wt.) with increasing PLA block length. Thus, the highest loading content of the anticancer drug oxaliplatin with its encapsulation efficiency of 76% in mPEG113-b-P(D,L)LAn nanoparticles can be achieved for block copolymer with short hydrophobic block.


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