Effect of molecular weight on gelling and viscoelastic properties of poly(Caprolactone)–b‐ poly(ethylene glycol)–b‐poly(caprolactone) (PCL– PEG–PCL) hydrogels

Noam Y. Steinman, Noam Y. Bentolila, Abraham J. Domb*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

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.

Original languageEnglish
Article number2372
Pages (from-to)1-12
Number of pages12
JournalPolymers
Volume12
Issue number10
DOIs
StatePublished - Oct 2020

Bibliographical note

Publisher Copyright:
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Keywords

  • Injectable hydrogels
  • PEG–PCL
  • Pseudoplastic

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