A substance that donates a proton (H⁺) in a chemical reaction. Many acids used in polymerization are Brønsted-Lowry acids, initiating reactions or acting as catalysts.

在化学反应中提供质子 (H+) 的物质。许多用于聚合的酸是布朗斯特德-洛瑞酸，引发反应或充当催化剂。(zài huà xué fǎn yìng zhōng tí gōng zhì zǐ (H+) de wù zhì. xǔ duō yòng yú jù hé de suān shì bù lóng sī tè dé - luò ruì suān, yǐn fā fǎn yìng huò chōng dāng cuī huà jì.)