Polysulfones

These materials are an important group of engineering plastics. Aliphatic polysulfones were first synthesized at the end of the nineteenth century [109]. That synthesis was based on reactions of SO₂ with olefins:

Aliphatic sulfones, however, lack good thermal stability and are not commercially important. Aromatic sulfones, on the other hand, have many desirable physical properties. They are clear, rigid, tough materials, with a high Tg. Several aromatic sulfones are prepared commercially.

The original preparation of aromatic polysulfones was described in 1958 [110]. This was followed by investigations of many different structures of polysulfones. One current commercial material is a condensation product of 2,2′ bis(hydroxyphenyl) propane with 4,4′-bis(chlorophenyl) sulfone. It forms by a Williamson synthesis, because the reactivity of the halogens is enhanced by the sulfone groups [47]:

The condensation takes place at 160°C in an inert atmosphere and in some suitable solvents, like chlorobenzene. Commercially, polymers are available in molecular weight ranges from 20,000 to 40,000. Much higher molecular weight materials, however, form readily. Aromatic polysulfones also form by the Friedel-Craft reaction [111], as for instance:

The reaction takes place at 80-250°C in a solution or in the melt. Lewis acid catalysts are used in concentrations of 0.1-1.0 mole percent. Cross-linking through polysubstitution does not appear to be a problem. Some chain branching, however, does occur because ortho substitution is possible:

It is estimated, however, that the ortho substitution amounts to not more than 5-10%. Removal of the catalyst after the reaction is tedious. Table 7.6 presents the Tg values of some aromatic polysulfones.

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اخبار العتبة العباسية المقدسة

المجمع العلمي يقيم مهرجانًا بذكرى الولادات الشعبانية في بغداد

معهد القرآن الكريم النسوي يباشر استعداداته لإقامة مهرجان السقاء القرآني السنوي الخامس

بالتعاون مع جامعة ستانفورد.. جامعة الكفيل تعتمد منهجًا متطورًا لطب الطوارئ

سماحة السيد الصافي يستقبل وفد شركة (سيتي فارما) الباكستانية المختصة في الأدوية

المزيد

الآخبار الصحية

اللحظات الأخيرة قبل الموت.. هذا هو تسلسل "فقدان الحواس"

وخز الأطراف وضعف الذاكرة.. علامات على نقص فيتامين هام

عادة صباحية بسيطة.. تأثيرها قد يحسن ضغط الدم

عادات يومية تدمر قلبك بصمت.. خبراء يطلقون التحذير

المزيد

الآخبار التكنلوجية

الذكاء الاصطناعي يفك لغز آثار أقدام الديناصورات

القمر أولا.."سبيس إكس" تؤجل خططها الخاصة بالرحلات إلى المريخ

الذكور أم الإناث؟ دراسة "تنسف الشائع" بشأن التوحد

خبير يكشف عن اقتراب العلماء من فك شفرات "لغات الحيوانات" !

المزيد

مواضيع ذات صلة

Polyurethane Fibers

The Effect of Catalysts

Chemical Reactions of the Isocyanates

Commercial Polyisocyanates

Polyurethanes

Poly(p-xylylene) s

Polyacetals and Polyketals

Phenoxy Polymers

Polyimides

Aromatic Polyamide-Imides and Aromatic Polyester-Imides

Aromatic Polyamides

Special Reactions for Formation of Polyamides