In some aspects, the present disclosure provides vaccine compositions comprising an antigen and a diblock copolymer wherein the diblock copolymer is pH responsive. In some embodiments, these compositions activate the STING and/or the interferon receptor pathways. In some embodiments, the diblock copolymer hits a pKa from about 6 to about 7.5. Also provided herein are methods of treatment using these compositions to treat an infectious disease or cancer.