Poly-L-lactide (PLLA) is a popular choice for medical devices due to its
bioresorbability and superior mechanical properties compared with other
polymers. However, although PLLA has been investigated for use in bioresorbable
cardiovascular stents, it presents application-specific limitations which
hamper device therapies. These include low toughness and strength compared with
metals used for this purpose, and slow degradation. Blending PLLA with novel
polyethylene glycol functionalised
poly(L-lactide-co-$\varepsilon$-caprolactone) (PLCL-PEG) materials has been
investigated here to tailor the mechanical properties and degradation behaviour
of PLLA. This exciting approach provides a foundation for a next generation of
bioresorbable materials whose properties can be rapidly tuned. The degradation
of PLLA was significantly accelerated by addition of PLCL-PEG. After 30 days of
degradation, several structural changes were observed in the polymer blends,
which were dependent on the level of PLCL-PEG addition. Blends with low
PLCL-PEG content displayed enthalpy relaxation, resulting in embrittlement,
while blends with high PLCL-PEG content displayed crystallisation, due to
enhanced chain mobility brought on by chain scission, also causing
embrittlement. Moderate PLCL-PEG additions (10% PLCL(70:30)-PEG and 20 - 30%
PLCL(80:20)-PEG) stabilised the structure, reducing the extent of enthalpy
relaxation and crystallisation and thus retaining ductility. Compositional
optimisation identified a sweet spot for this blend strategy, whereby the
ductility was enhanced while maintaining strength. Our results indicate that
blending PLLA with PLCL-PEG provides an effective method of tuning the
degradation timescale and mechanical properties of PLLA, and provides important
new insight into the mechanisms of structural relaxations that occur during
degradation, and strategies for regulating these.Lucideon Lt

Best, SM

Cameron, RE

Duffy, P

Kwon, KA

McMahon, S

Oosterbeek, RN

Zhang, XC

English

Apollo (Cambridge)

Tuning structural relaxations, mechanical properties, and degradation timescale of PLLA during hydrolytic degradation by blending with PLCL-PEG

Thermal data measured by DSC for blends of PLLA with PLCL(70:30)-PEG or PLCL(80:20)-PEG, either before (Fig01) or after (Fig08) degradation. Contains Microsoft Excel files with Tg measurements and experimental details, as well as measured changes in enthalpy of relaxation after degradation. Example raw DSC curves are also given (.txt format), as well as script and data files for generating plots (.txt).
Molecular weight distributions for blends of PLLA with PLCL(70:30)-PEG or PLCL(80:20)-PEG, measured by GPC, either before (Fig02) or after (Fig06) degradation. Contains Microsoft Excel files with raw GPC curves. Average molecular weights are also given in a Microsoft Excel file (Table01). Measured distributions for blends are compared with a calculated distribution based on a linear combination of individual blend components. Script and data files for generating plots (.txt) are also included.
Mechanical testing data from tensile tests of blends of PLLA with PLCL(70:30)-PEG or PLCL(80:20)-PEG (Fig03). Tests were carried out before degradation in the dry state, before degradation in 37°C water, and after degradation in 37°C water. Contains Microsoft Excel files with measured properties and example stress-strain curves, as well as script and data files for generating plots (.txt).
Degradation pH measurements from degradation of blends of PLLA with PLCL(70:30)-PEG or PLCL(80:20)-PEG in PBS at 37°C (Fig04 and Fig05). Contains Microsoft Excel files with raw pH measurements over time, as well as photographs of polymer samples during degradation. Script and data files for generating plots (.txt) are also included.
Raw SEM images (.tif) of an 80:20 blend of PLLA and PLCL(70:30)-PEG before and after degradation are included (Fig07).
Crystallinity data measured by XRD for blends of PLLA with PLCL(70:30)-PEG or PLCL(80:20)-PEG, either before (FigS1) or after (Fig09) degradation. Contains Microsoft Excel files experimental details, and sample codes. Example raw XRD patterns are also given (.uxd format), as well as script and data files for generating plots (.txt).
Plots are generated using gnuplot (www.gnuplot.info),The authors thank Lucideon Ltd. for financial support of the project. RNO also thanks the Woolf Fisher Trust and the Cambridge Trust for provision of a PhD scholarship

Oosterbeek, Reece

Duffy, Patrick

McMahon, Sean

Zhang, Xiang

Best, Serena

Cameron, Ruth

Research data supporting "Tuning structural relaxations, mechanical properties, and degradation timescale of PLLA during hydrolytic degradation by blending with PLCL-PEG"

https://www.repository.cam.ac.uk/bitstream/handle/1810/298724/2019%20Oosterbeek%20et%20al%2c%20Tuning%20structural%20relaxations%2c%20mechanical%20properties%20and%20degradation%20timescale%20of%20PLLA%20during%20hydrolytic%20degradation%20by%20blending%20with%20PLCL-PEG.pdf?sequence=1&isAllowed=y

Tuning structural relaxations, mechanical properties, and degradation timescale of PLLA during hydrolytic degradation by blending with PLCL-PEG

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