Near-critical micellization (NCM), allowing for precise pressure-tuned control of sequential block collapse and micelle formation, can be synchronized with cancer-drug encapsulation with virtually no drug losses. NCM is demonstrated to produce benign, stable nanoparticles made of PEG-b-PLLA-b-PCL triblock copolymers that are not only solvent-free and paclitaxel-rich, which reduces the body exposure to the excipients, but also nearly burst-release-free, which reduces if not eliminates its toxic side effects while enhancing its therapeutic efficacy.