Tailoring the self- and co-assembly pathways of amphiphilic and double hydrophilic block copolymers by modulation of both equilibrium and out-of-equilibrium routes enables the non-covalent synthesis of well-defined, nanostructured hydrocolloids with a hierarchical internal structure, tuneable dynamics, and interesting functional properties. In this lecture I will discuss our recent work (bio)polymer self-assembly in synthetic (part 1) and biological (part 2) soft matter. In part 1, I will show how to create precision polymer particles built from oppositely charged copolymers (complex coacervate core micelles, C3Ms), from amphiphilic polymers (single chain polymeric nanoparticles, SCPNs), and from protein/copolymer mixtures. I will focus on the unique structure-function relations of these precision polymer particles, the interplay between the various relevant supramolecular interactions underpinning these, and their relevance for the preparation of Janus micelles, the time-gated disassembly of C3Ms, the templated synthesis of nanoparticles at room temperature, the activity of protein liquids, and ice recrystallization inhibition. In part 2, I will address how intra- and intermolecular assembly of native biopolymers, known as ice-binding proteins (IBPs), and their synthetic mimics impacts ice crystal growth. Our aim is to achieve a solid mechanistic understanding of how natural IBPs work as a crucial first step for the knowledge-based design of potent macromolecular ice crystal growth modifiers. Successful encoding of the cryoprotective functionality of IBPs into synthetic polymers would open up new avenues for e.g. cryopreservation, de-icing technologies and advanced coatings.