*2.1. Materials*

Commercial PLLA Luminy® L175 was obtained from Total Corbion (The Netherlands) with D-lactide content below 1%, according to the supplier. Weight average molar mass M w of 78 kg/mol and dispersity M w/Mn of 1.8 were measured by size exclusion chromatography (SEC) with a multi-angle laser light scattering detector in dichloromethane using an Agilent Pump 1100 Series (preceded by an Agilent G1379A Degasser), equipped with a set of two PLGel 5 μ MIXED-C columns. A Wyatt Optilab Rex differential refractometer and a Dawn Eos (Wyatt Technology Corporation) laser photometer were used as detectors. Dichloromethane was used as eluent at a flow rate of 0.8 mL min-<sup>1</sup> at room temperature (RT).

MWCNT Nanocyl NC-7000 (Nanocyl, Belgium) with an average diameter of 9.5 nm, length of 1.5 μm, and 90% purity, were used. PLLA covalently attached to MWCNT (PL-g-CNT) was synthesized by ring-opening polymerization of L,L-lactide according to a well-established procedure [53,54]. LPSQ-COOMe was synthesized as previously described [38,39]. Procedures for the synthesis of PL-g-CNT and LPSQ-COOMe are described below.

Dichloromethane purchased from StanLab (Poland) (purity 99.5%) and acetone purchased from POCH (Poland) (purity 99%) were used as received.

## *2.2. Synthesis of PL-g-CNT*

Ring-opening polymerization of L,L-lactide was carried out as follows: Sn(Oct)2 (1 mL of 0.25 mol L−<sup>1</sup> solution in dry tetrahydrofuran (THF)) and L,L-Lactide (L,L-LA, 7.42 g, 51.5 mmol) were transferred under vacuum into break-seals and then sealed after being frozen in liquid N2. MWCNT−OH (7.4 mg) was placed directly into the reaction ampule, dried under vacuum for 4 h, and sealed. Break-seals that contained the Sn(Oct)2/THF solution and L,L-LA monomer and a tube that contained dry MWCNTs in a vial were sealed to the glass reaction vessel (∼10 mL). Under vacuum, the break-seals and vial were broken, and all components were mixed at RT. THF was removed by distillation, and then the reaction vessel was sealed. The reaction vessel was placed into an ultrasonic bath for 60 min (130◦C) to disperse MWCNT−OH, then placed into a thermostated oil bath, and the polymerization was carried out at 130 ◦C for approx. 24 h. The resulting polymer was dissolved in CHCl3 and precipitated into methanol, separated by filtration, and washed several times with methanol. The mass of the vacuum-dried product was 6.31 g (85% yield). The content of MWCNTs in the product was 0.1 wt.%. The molecular characteristics of the product were determined according to the procedure described previously [53]. It was found that PL-g-CNT was a mixture composed of PLLA grafted on MWCNT and free PLLA. Only approximately 15−20 wt.% of the PLLA chains were found to be polymerized from the MWCNT. Mw and Mw/Mn of the free PLLA fraction were 82 kg/mol and 1.4, respectively, as determined by SEC using the equipment described above. The molar masses of both PLLA fractions should be similar [55]. 1H NMR of PL-g-CNT (CDCl3): δ= 5.16 (q, 1H, CH-CH3 polymer), 1.67 (d, 3H, CH3 polymer) ppm.

## *2.3. Synthesis of LPSQ-COOMe*

LPSQ-COOMe was synthesized as previously described [38,39]. Methyl thioglycolate (Acros Organics, 95%) was added into a solution of ladder-like poly(vinylsilsesquioxanes), Mn = 1000 g/mol, Mw/Mn = 1.4, obtained as described in [56], dissolved in dry THF (c = 8 wt.%) and placed in a quartz crucible. The ratio of reagents was [HS]0/[Vi]0 = 1.4). A photoinitiator (2,2-dimethoxy-2-phenylacetophenone, Acros Organics, 99%) was then added with stirring to the solution of reagents at [Vi]0/[DMPA]0 = 50. The mixture was irradiated for 15 min with UV light (λ = 365 nm). Volatiles were removed under reduced pressure and the residue was purified by precipitation into a large amount of hexane/ethyl acetate (1: 1 *v*/*v*). The product was dried under high vacuum at RT to the constant weight (reaction yield 91%) and characterized with 1H NMR spectroscopy using a Bruker DRX-500 MHz spectrometer: δ [ppm] (THF-d8): 0.16 (s. OSiMe3), 1.06 (m. SiCH2), 2.77 (m. CH2S), 3.25 (m. SCH2), 3.65 (s. OCH3). The 1H NMR spectrum is shown in Figure S1 of Supporting Information (SI). Full NMR characteristics have been previously published in [38,39].

The obtained LPSQ-COOMe was essentially an amorphous substance with Tg at −41.2 ◦C as determined by DSC during heating at 10 ◦C /min from −100 ◦C.

## *2.4. Preparation of Nonwovens*

Before further use, commercial PLLA pellets were dried under reduced pressure for 4 h at 100 ◦C. After drying, PLLA was dissolved in dichloromethane to obtain 12 wt.% solution. LPSQ-COOMe was added to PLLA solution to obtain 5:100 and 10:100 weight ratios of the modifier to PLLA (PL-LPSQ5, PL-LPSQ10). Furthermore, MWCNT were added to the solution containing neat PLLA and PLLA with LPSQ-COOMe to obtain 1:1000 weight ratio of MWCNT to PLLA (PL-CNT, PL-LPSQ5-CNT, PL-LPSQ10-CNT). All the solutions and dispersions were mixed with acetone in a volume ratio of 7:3. The dispersions were homogenized using an ultrasonic homogenizer, the Hielscher UP 200S (Hielscher, 130 Germany, power 200 W, amplitude 30%, frequency 24 kHz), at RT for 20 min.

PL-g-CNT was dissolved in dichloromethane to obtain a 6 wt.% solution. Then the solution was mixed with acetone in a volume ratio of 7:3 and homogenized, as described above.

PLLA-based nonwovens were electrospun at RT and relative humidity of 35 –40% using a system consisting of a high voltage power supply CM5 (Simco-Ion, The Netherlands) and an aluminum plate 8 × 8 cm as a collector. Glass syringes and a step motor, model T-LLS105 from Zaber (Canada), were used for dosing of solutions. The tip-collector distance was 25 cm in all cases. The parameters of the electrospinning are listed in Table 1. The polymer concentrations in the solvent and other parameters of the electrospinning were selected based on preliminary experiments. The preparation scheme of the nonwovens is shown in Figure S2 in SI.

**Table 1.** Parameters of electrospinning.


The obtained nonwovens were dried for 4 h at 35 ◦C under reduced pressure and then stored in a desiccator at RT. All measurements were carried out at least two days after the electrospinning.
