Tetrahydrofuran

Poly-d,l-lactide-co-glycolide (RG502H; lactide:glycolide molar ratio, 50:50; inherent viscosity of a 0.1% concentration in CHCl₃, 0.20 dL/g) was purchased from Evonik Corporation (Theodore, AL, USA). This polymer, abbreviated as PLGA in the text, was used as a microsphere-forming material. Poly (vinyl alcohol) (PVA; 88 mol% hydrolyzed; molecular weight, 25,000 g/mol) was obtained from Polysciences, Inc. (Warrington, PA, USA). Progesterone, ethyl formate, acetone, hydroxypropyl methylcellulose (HPMC; viscosity of a 2% aqueous solution, 40~60 cP), and Tween 80 were procured from Merck Korea (Seoul, Korea). A 28% ammonia solution was obtained from Junsei Chemical Co., Ltd. (Tokyo, Japan). Methanol and tetrahydrofuran were supplied from Honeywell Korea (Seoul, Korea).

Chloroprene Rubber (CR; SN 122 grade) was supplied by The Weir Group PLC (Glasgow, UK). Thiokol (TLP; LP-3 grade; mercaptan terminated liquid polysulfide polymer of n diethyleneoxymethane units connected with Sx linkages, where 6 ≤ N ≤ 42 and x predominantly equal to 2) was purchased from Wessington Group Ltd. (Reading, UK). 2,2′-Azobis(2-methylpropionitrile) (AIBN; 98% purity; free radical initiator), Stearic Acid (StA; 95% purity, reagent grade) and Chloroform-d (CDCl3; 99.8 atom % D) were purchased from Sigma-Aldrich Co Ltd. (Dorset, UK). Magnesium Oxide (MgO; ≥97% purity, Light Technical grade) and Zinc Oxide (ZnO; ≥98% purity, Light Technical grade) were purchased from VWR International Ltd. (Leicestershire, UK). Toluene (≥99.9% purity, HPLC grade) and Tetrahydrofuran (THF; ≥99.9% purity, inhibitor free, HPLC grade) were purchased from Honeywell International Inc. (Bracknell, UK).
In the present work CR/TLP blends were tested in different conditions, before and after curing, healing and recycling. The terminology adopted to refer to the blends in specific conditions is as follows:

Compound: something that has been mixed, but not cured.

Cured compound: new cured compound.

Healed compound: cured compound healed after damage induction.

Recycled compound: recycled cured compound.

The monomers GMA (≥97%) and BA (≥99%), the macromonomer PEGMA (average molecular weight Mn = 950 g/mol) and the initiator azobisisobutyronitrile (AIBN) were purchased from Aldrich (Taufkirchen, Germany) and used as received. The solvents tetrahydrofuran (THF, anhydrous, p.a, ≥99.9%), 1,4-dioxane (p.a, ≥99.8%), hexane and diethyl ether (p.a, ≥99.5%) were obtained from Carlo Erba (Milano, Italy), while the solvent chloroform (p.a, ≥99.8%) was obtained from Honeywell (Ile de France, France). These solvents were used as received without further purification. Deuterated chloroform (CDCl₃, 99.8% D) was purchased from Eurisotop (Saint-Aubin, France). The waterborne polyurethane dispersions WPU1 and WPU2 were kindly provided by Megara Resins SA (Megara, Greece). These WPUs have been synthesized through the prepolymer method, using the same diisocyanate agent. In WPU1, a polycarbonate polyol was utilized while in WPU2, a polyether-ester polyol was used. Moreover, it should be noted that WPU2 was a hybrid-alkyd PU, instead of WPU1 which was pure PU.
Ultra-pure water was obtained by means of an Arium mini water purification system from Sartorius (Goettingen, Germany).

Acetonitrile, ethanol, methanol and dimethyl formamide were purchased from Sigma-Aldrich (Taufkirchen, Germany), tetrahydrofuran and dimethyl sulfoxide from Honeywell (Seelse, Germany) and water for injection from BIOSER (Trikala, Greece). Tests were performed by adding 1mg of Tegaran capsule content to test tubes containing 1ml of solvent and mixing by using a Stuart vortex mixer SA8 (Staffordshire, United Kingdom) for 5min at 2500rpm and an mrc sonication bath AC-150H (Essex, United Kingdom) for 5min. The quantity of each solvent was increased until final volume of 10ml and solubility was assessed visually.