Facile Fabrication of Photochromic Poly(lactic acid)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Fibers via a Scalable Melt-Spinning Process

Due to their green, low-carbon, and sustainable resource qualities, photochromic poly(lactic acid) (PLA) fibers provide various advantages in the development of smart textiles, such as sensing and camouflage. However, the stiffness and rough texture of functional PLA fibers can have an impact on textile comfort and restrict their application. In our work, we used a scalable melt-spinning approach to create photochromic fibers with PLA and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as fiber-forming polymers and photochromic microcapsules as color indicators, respectively. When exposed to intense sunlight, photochromic PLA/PHBV fibers transform from colorless to blue in 1 s then back to colorless in 1 min when the activation irradiation is removed. The tenacity and initial modulus of photochromic PLA/PHBV fibers decrease from 4.30 to 3.57 cN/dtex and 66.20 to 27.91 cN/dtex, respectively, as the PHBV component content increases from 0% to 20% wt %, suggesting acceptable tenacity and good flexibility. As the PHBV content increases, PHBV can nucleate PLA to promote the crystal growth rate of PLA, but it results in thinner or less perfect PLA lamellae and a more disordered amorphous region in the photochromic PLA/PHBV fibers. This structure reduces the tenacity of photochromic PLA/PHBV fibers while enhancing softness.