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

Dueto their green, low-carbon, and sustainable resource qualities,photochromic poly(lactic acid) (PLA) fibers provide various advantagesin the development of smart textiles, such as sensing and camouflage.However, the stiffness and rough texture of functional PLA fiberscan have an impact on textile comfort and restrict their application.In our work, we used a scalable melt-spinning approach to create photochromicfibers with PLA and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)as fiber-forming polymers and photochromic microcapsules as colorindicators, respectively. When exposed to intense sunlight, photochromicPLA/PHBV fibers transform from colorless to blue in 1 s then backto colorless in 1 min when the activation irradiation is removed.The tenacity and initial modulus of photochromic PLA/PHBV fibers decreasefrom 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 %, suggestingacceptable tenacity and good flexibility. As the PHBV content increases,PHBV can nucleate PLA to promote the crystal growth rate of PLA, butit results in thinner or less perfect PLA lamellae and a more disorderedamorphous region in the photochromic PLA/PHBV fibers. This structurereduces the tenacity of photochromic PLA/PHBV fibers while enhancingsoftness.