scholarly journals Effect of Molecular Weight on Gelling and Viscoelastic Properties of Poly(caprolactone)–b-Poly(ethylene glycol)–b-Poly(caprolactone) (PCL–PEG–PCL) Hydrogels

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2372
Author(s):  
Noam Y. Steinman ◽  
Noam Y. Bentolila ◽  
Abraham J. Domb

Hydrogels based on poly(caprolactone)–b-poly(ethylene glycol)–b-poly(caprolactone) (PCL–PEG–PCL) have been evaluated extensively as potential injectable fillers or depots for controlled release of drugs. Common drawbacks of these copolymer systems include instability of aqueous solutions and low mechanical strength of gels, issues which are commonly overcome by adding pendant groups to the end of the copolymer chains. Here, a systematic study of the effects of increasing polymer molecular weight (MW) is presented, utilizing PEG blocks of MW 2, 4 or 8 kDa. Triblock copolymers were prepared by the ring-opening polymerization of Ɛ-caprolactone by PEG. Copolymers prepared with PEG MW 2 kDa did not form hydrogels at any copolymer molecular weight. Copolymers prepared with PEG MW 4 kDa formed gels at MW between 11 and 13.5 kDa, and copolymers prepared with PEG MW 8 kDa formed gels at MW between 16 and 18 kDa. Copolymers with PEG block 8 kDa formed hydrogels with high viscosity (17,000 Pa·s) and mechanical strength (G′ = 14,000 Pa). The increased gel strength afforded by increased molecular weight represents a simple modification of the reactants used in the reaction feed without added synthetic or purification steps. Shear-thinning of PCL-PEG-PCL triblock copolymer hydrogels allowed for injection through a standard 23G syringe, allowing for potential use as dermal fillers or drug delivery depots.

Nitric Oxide ◽  
2004 ◽  
Vol 11 (3) ◽  
pp. 263-272 ◽  
Author(s):  
Amedea Barozzi Seabra ◽  
Gabriela Freitas Pereira de Souza ◽  
Lilian Lúcia da Rocha ◽  
Marcos Nogueira Eberlin ◽  
Marcelo Ganzarolli de Oliveira

2007 ◽  
Vol 208 (24) ◽  
pp. 2642-2653 ◽  
Author(s):  
Alena Braunová ◽  
Michal Pechar ◽  
Richard Laga ◽  
Karel Ulbrich

2004 ◽  
Vol 70A (1) ◽  
pp. 154-158 ◽  
Author(s):  
Moon Suk Kim ◽  
Kwang Su Seo ◽  
Gilson Khang ◽  
Sun Hang Cho ◽  
Hai Bang Lee

2012 ◽  
Vol 567 ◽  
pp. 123-126
Author(s):  
Teng Fei Shen ◽  
Man Geng Lu ◽  
Li Yan Liang

In this work, microporous membrane biomaterials based on high weight molecular polylactide (PLA) and low molecular weight poly(ethylene glycol) (PEG) using rapid solvent evaporation method were prepared and investigated. The effect of PEG segments added on the thermal and degradation behaviors was studied. According to the results, produced PLA/PEG biomaterial has lower glass transition temperature (Tg)in comparison with neat PLA. It was also found that the degradation rates of the PLA/PEG biomaterials were significantly increased with adding of PEG, which explained by increasing hydrophilic groups. For better porous fixation, CL-blocked polyisocyanate (CL-bp), which was synthesized from reaction of isophorone diisocyanate (IPDI) with dimethylol propionic acid (DMPA) and Trimethylolpropane (TMP) followed by addition of caprolactam (CL), were introduced. The microporous forms were observed by the scanning electron microscope (SEM), which showed the mean diameters of prepared PLA/PEG microporous were around 10μm.


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