In this paper, the hydrophobic effect or hydration of hydrophobe was firstly introduced into the mechanism of polystyrene particles formation. Negatively charged surface of hydration shell was proposed due to the ordered structure of water molecules. Consequentially the concentration of hydrophobic chains depended on pH because protons destroyed the hydration shell, thereby extruded hydrophobic chains from the H-bonds networks. The soap-free emulsion polymerization of styrene by using AIBN (azodiisobutyronitrile) and KPS (Potassium Persulfate), respectively was performed at various pHs. It was proved that protons played a crucial role on the formation of PSt (polystyrene) particles. By using AIBN, particles were not prepared at pH 2.0 (HAc), pH 4.0 (HCl) and pH 2.0 (HCl), whereas by using KPS, particles were obtained regardless to pH. It indicated that anions of sulfate greatly enhanced the tolerance of hydration shell to the suffering from protons. Meanwhile, the roles of polymerization in the monomer phase, aqueous phase and growing particles were elucidated. By using AIBN, ca. 30 % PSt with M n (Numeral average molecular weight) = 300-1500 formed in the monomer phase at pH 6.8, which dissolved in water at pH 8.0 and pH 10.0. By using KPS, ca. 20 % and 30 % conversion of St were found in the aqueous phase at pH 2.0 (HCl) and pH 10.0 (NaOH), respectively. At pH 2.0 (HCl), oligomers generated in the aqueous phase were protonated, whereas at pH 10.0 (NaOH), they were soluble due to the seriously suppressed dissociation of water. At other pHs, oligomers captured protons, thereby relieved particles and interface from the suffering of protons. As the concentration of oligomers increased, oligomers precipitated to form clusters due to the increase of average number of protons on the surface of oligomers hydration shell, which successively incorporated into the growing particles, thus enlarged PDI (Polydispersity index) of MW (Weight-average molecular weight) distribution in particles. By using AIBN, owing to the limited partition of AIBN in the interfacial layer of St phase, the flat-roof peaks of GPC curves were observed, namely that the weight fraction of M i was constant. It implies that the freeradicals are living in the growing particles.

AbstractAccording to the concept of fire life cycle assessment (LCA), a new type of intumescent flame retardant was designed and synthesized by chemically bonding chitosan, phosphorus pentoxide and melamine. The resultant compound, chitosan ethoxyl melamine phosphate (CEMP), was characterized by FTIR, 1H NMR, 31P NMR, XRD and SEM. The performance of CEMP and organic montmorillonite (OMMT) was evaluated in the substrate of epoxy resin (EP) with limited oxygen index (LOI), UL-94, cone calorimetric test (CCT), TGA and TG-IR. As a result, intumescent flame retardant EP (EP3) containing 30.6% LOI and V-0 rating was prepared by adding 3 wt% OMMT and 15 wt% CEMP. The CCT results indicated that CEMP and OMMT reduced the peak of heat release rate (PHRR) to about one fourth that of pure EP and total heat release (THR), 1/2. Decomposition of EP and EP3 was traced from 100 to 600°C by TG-IR.

According to the requirement of fire life cycle assessment (LCA), chitosan ethoxyl urea phosphate (CEUP), an organic–inorganic intumescent flame retardant (IFR) containing phosphorus, nitrogen, and silicon, was synthesized by the reaction of chitosan, phosphorus pentoxide, and urea. FTIR, 1H NMR, SEM, and XRD were employed to characterize the compounds. As a result, CEUP was successfully prepared with higher thermal stability, favorable to enhance fire resistance. Combined with OMMT, the organic/inorganic IFR was applied as EP flame‐retardant agents. The combustion behavior of EP composite was investigated by LOI, UL‐94, CCT, SEM, TGA, and TG‐IR. It was observed that using 15% CEUP and 3% OMMT (EP3), LOI value reached 34.8% and passed the UL‐94 V‐0 rating, while THR and TSP of EP composite reduced 65 and 72% compared with pure EP. The char residue of EP composite was up to 22.4%. The thermal decomposition mechanism was traced from 100 to 600°C by TG‐IR. It was suggestive that CEUP decomposition commenced at 100°C to create phosphoric acid and sublimation of urea occurred at 300°C. EP3 exhibited a strong thermal stability, namely even at 600°C, the volatile substances were detectable. Dense and expanded carbon layer was confirmed in SEM images.

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In this paper, the alcoholization of lyophobic monomer similar to the hydration was introduced into the mechanism of polystyrene microspheres formation in alcohols. Entropic charges emerged on the surface of alcoholization shell due to the order structure of alcohol molecules. Such an electricnegative atmosphere attracted protons and cations which finally destroyed the alcoholization shell to release the lyophobic monomer. It was considered as the decisive factor on the stability of monomer mini-droplets and the microspheres. Large number of protons favored the phase-separation of monomer-solvent and the stabilization of microspheres, but unfavored the stability of mini-droplets. The precipitation polymerization of styrene was carried out in alcohols of EG, MeOH, EtOH and IPA by using AIBN. It was observed that pK a of alcohol significantly impacted the microspheres formation. Microspheres were prepared in EG and MeOH, but not in EtOH and IPA. According to the proposition of entropic charges, MAA, HAc, NaOH and KOH were employed to adjust the concentration of protons in EtOH and IPA. Consequentially, the microspheres were obtained by adding HAc, NaOH and KOH in EtOH and IPA. Effects of NaOH/KOH on the molecular weight of PSt and the size of microspheres were also investigated in EtOH and IPA. Microspheres of 0.93 and 1.11 μm were prepared with 15 wt% St and 0.1154 mol/L NaOH in EtOH and IPA, respectively, but not obtained with KOH.