环氧树脂AB胶为什么要两管混着用？
Why must two-part epoxy be mixed before use?
树脂和固化剂分开时稳定，混合后引发交联反应变硬成三维网络，比例和混合均匀程度都影响最终强度。
Resin and hardener stay stable apart; mixed, they crosslink into a 3D network. Ratio and thorough mixing decide the final strength.
难度 专业 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
邢其毅 等,《基础有机化学》第4版,北京大学出版社,2016
Xing Qiyi et al., Basic Organic Chemistry, 4th ed., Peking University Press, 2016
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787301272121（豆瓣书目条目: 基础有机化学）
#环氧树脂 #固化 #交联
可控自由基聚合(ATRP/RAFT)与普通自由基聚合相比,分子量分布为什么明显更窄?
Compared with conventional free-radical polymerization, why do controlled radical polymerizations such as ATRP and RAFT give much narrower molecular weight distributions?
普通自由基聚合中链增长与链终止竞争剧烈,链一旦引发便不可逆地增长至死亡,各链寿命差异大,故分布接近高斯且PDI常在1.5以上。ATRP通过卤原子可逆钝化使活性种与休眠种之间快速交换,RAFT则通过硫代羰基硫化合物可逆加成断裂链转移实现同样的休眠-活化平衡。每条链经历多次活化-钝化循环,增长机会被均摊,所有链近似同步生长,数均分子量随转化率线性上升,PDI可降到1.1左右甚至更低。
In conventional radical polymerization, propagation competes irreversibly with termination: once initiated, a chain grows until it dies, chain lifetimes differ widely, and the distribution approaches Gaussian with PDI typically above 1.5. ATRP establishes a rapid equilibrium between active and dormant species via reversible halogen atom transfer, while RAFT achieves the same dormancy-activation balance through reversible addition-fragmentation chain transfer with thiocarbonylthio compounds. Every chain undergoes many activation-deactivation cycles, growth opportunities are equalized, all chains grow nearly synchronously, Mn rises linearly with conversion, and PDI drops to about 1.1 or lower.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Matyjaszewski 与 Xia,《Atom Transfer Radical Polymerization》,Chemical Reviews,2001 (DOI: 10.1021/cr940534g)
Matyjaszewski & Xia, 'Atom Transfer Radical Polymerization', Chemical Reviews, 2001, DOI: 10.1021/cr940534g
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1021/cr940534g
#可控自由基聚合 #分子量分布
为什么油画颜料能自己变硬成膜？
Why do oil paints harden into a film by themselves?
亚麻油等含大量不饱和双键，与空气中的氧发生交联聚合（自干），形成坚固干膜；但老旧清漆会氧化发黄。
Linseed oil's unsaturated bonds cross-link with oxygen (auto-oxidation) into a tough film; old varnishes yellow with oxidation.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
邢其毅 等,《基础有机化学》第4版,北京大学出版社,2016
Xing Qiyi et al., Basic Organic Chemistry, 4th ed., Peking University Press, 2016
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787301272121（豆瓣书目条目: 基础有机化学）
#亚麻油 #干性油 #聚合
涤纶、尼龙这类合成纤维是怎么造出来的？
How are synthetic fibers like polyester and nylon made?
它们由小分子单体通过缩聚或加聚反应连成长链高分子，再熔融或溶液纺丝拉成细丝。
Small monomers link into long polymer chains by condensation or addition, then are melt- or solution-spun into filaments.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
邢其毅 等,《基础有机化学》第4版,北京大学出版社,2016
Xing Qiyi et al., Basic Organic Chemistry, 4th ed., Peking University Press, 2016
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787301272121（豆瓣书目条目: 基础有机化学）
#合成纤维 #聚合 #纺丝
聚氯乙烯(PVC)为什么从氯乙烯单体而来？
Why is PVC made from vinyl chloride monomer?
氯乙烯在引发剂下聚合成聚氯乙烯长链，氯原子的存在让材料更硬、更阻燃，但残留单体有毒需严格控制。
Vinyl chloride polymerizes into PVC chains; the chlorine makes the plastic rigid and flame-retardant, though residual monomer is toxic and tightly controlled.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
邢其毅 等,《基础有机化学》第4版,北京大学出版社,2016
Xing Qiyi et al., Basic Organic Chemistry, 4th ed., Peking University Press, 2016
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787301272121（豆瓣书目条目: 基础有机化学）
#PVC #氯乙烯 #聚合
为什么阴离子聚合能得到窄分子量分布的聚苯乙烯,而传统自由基聚合很难做到?
Why does anionic polymerization give narrow-molecular-weight-distribution polystyrene while conventional free-radical polymerization hardly ever can?
阴离子聚合的活性链端是碳负离子,在严格除水除氧的体系中既不双基终止也难发生链转移,所有链几乎同步引发、同步增长。分子量分布因此接近泊松分布,重均与数均之比可低至1.05左右。自由基聚合中引发剂缓慢分解、链转移和随机双基终止叠加在一起,分散度通常落在1.5到2.0以上。
In anionic polymerization the growing ends are carbanions that neither terminate bimolecularly nor readily transfer in rigorously dried, oxygen-free systems, so essentially every chain starts and grows in step. The distribution therefore approaches a Poisson limit, with weight-average over number-average ratios as low as about 1.05. Slow initiator decomposition, chain transfer, and random radical termination combine to keep radical dispersities above roughly 1.5 to 2.0.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Szwarc,《‘Living’ Polymers》,Nature,1956 (DOI: 10.1038/1781168a0)
Szwarc, '‘Living’ Polymers', Nature, 1956, DOI: 10.1038/1781168a0
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1038/1781168a0
#高分子合成 #阴离子聚合
加聚与缩聚的主要区别是什么？
What is the main difference between addition and condensation polymerization?
加聚是烯烃等不饱和单体通过双键打开反复连接，不释放小分子，如聚乙烯。缩聚是带双官能团单体缩合，每步脱去水、醇等小分子，如聚酯、聚酰胺；前者产物与单体元素组成相同，后者不同。
Addition polymerization opens double bonds of unsaturated monomers (e.g., ethylene) and links them without byproduct, as in polyethylene. Condensation polymerization joins bifunctional monomers while eliminating small molecules like water or alcohol, as in polyesters and polyamides; the latter changes elemental composition.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#聚合 #加聚 #缩聚
硫化为什么让橡胶更耐用？
Why does vulcanization make rubber tougher?
硫在聚异戊二烯链之间架起“硫桥”交联，限制链滑移，从而提升弹性、强度与耐热性。
Sulfur forms crosslinks ('sulfur bridges') between polyisoprene chains, limiting chain slip and improving elasticity, strength and heat resistance.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Brown, LeMay 等,《Chemistry: The Central Science》第14版,Pearson,2017
T. L. Brown et al., Chemistry: The Central Science, 14th ed., Pearson, 2017
#硫化 #橡胶 #交联
502/万能胶为什么一沾水就粘住？
Why does super glue set the moment it meets water?
氰基丙烯酸酯遇痕量水(甚至空气里的湿气)就发生阴离子聚合，瞬间固化把两个面牢牢粘住。
Cyanoacrylate undergoes anionic polymerization on trace water—even ambient humidity—curing instantly to bond surfaces tightly.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
邢其毅 等,《基础有机化学》第4版,北京大学出版社,2016
Xing Qiyi et al., Basic Organic Chemistry, 4th ed., Peking University Press, 2016
独立核验依据 · Independent verification: 核验依据 2 ISBN 9787301272121（豆瓣书目条目: 基础有机化学）
#万能胶 #氰基丙烯酸酯 #聚合
同样是把小分子连成长链,加聚和缩聚的本质区别在哪里?
Both build long chains from small molecules — what truly separates addition from condensation polymerization?
区别在于是否脱去小分子以及链如何生长。加聚(如乙烯变聚乙烯)打开碳碳双键彼此相连,原子全部进入长链,一经引发便快速长成高分子量;缩聚(如己二酸与己二胺缩成尼龙66)每形成一根酰胺键就脱去一分子水,靠官能团两两碰撞逐步延长,反应程度须达99%以上才有足够长的链——这是卡罗瑟斯方程的硬约束。工程后果也不同:加聚物主链耐水解而化学回收难,缩聚物含极性键更耐温却怕水解。
Whether small molecules drop out and how chains grow. Addition polymerization (ethylene to polyethylene) opens C=C bonds with one hundred percent of atoms entering the chain; once initiated, chains race to high molecular weight. Condensation (adipic acid plus hexamethylenediamine to nylon-6,6) ejects a water molecule per amide bond and extends only by pairwise functional-group collisions, demanding extreme conversion above ninety-nine percent for useful chain lengths — Carothers equation sets the hard rule. Consequences differ too: addition polymers resist hydrolysis but are harder to reprocess chemically; condensation polymers carry polar bonds that love strength yet fear hydrolysis.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Odian,《Principles of Polymerization》第4版,Wiley,2004
G. Odian, Principles of Polymerization, 4th ed., Wiley, 2004
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-0-471-61020-5 (2004, Wiley)
#加聚反应 #缩聚反应 #尼龙