Complex coacervation driven liquid-liquid phase separation (LLPS) of biopolymers has been attracting attention as a novel phase in living cells. Studies of LLPS in this context are typically of proteins harboring chemical and structural complexity, leaving unclear which properties are fundamental to complex coacervation versus protein-specific. This study focuses on the role of polyethylene glycol (PEG)—a widely used molecular crowder—in LLPS. Significantly, entropy-driven LLPS is recapitulated with charged polymers lacking hydrophobicity and sequence complexity, and its propensity dramatically enhanced by PEG. Experimental and field-theoretic simulation results are consistent with PEG driving LLPS by dehydration of polymers, and show that PEG exerts its effect without partitioning into the dense coacervate phase. It is then up to biology to impose additional variations of functional significance to the LLPS of biological systems.

复杂凝聚驱动的生物聚合物液-液相分离（LLPS）作为活细胞中的一种新相而引起了人们的关注。在这种情况下，LLPS 的研究通常是针对具有化学和结构复杂性的蛋白质，但不清楚哪些特性是复杂凝聚与蛋白质特异性的基础。本研究重点关注聚乙二醇 (PEG)（一种广泛使用的分子拥挤剂）在 LLPS 中的作用。值得注意的是，熵驱动的 LLPS 可以用缺乏疏水性和序列复杂性的带电聚合物来概括，并且 PEG 大大增强了其倾向。实验和场论模拟结果与 PEG 通过聚合物脱水驱动 LLPS 一致，并表明 PEG 发挥其作用而无需分配到致密凝聚层相中。