Which is are correct about PMMA here? (1) It is called plexiglass. (2) It is hard and transparent. (3) For it is formation peroxide is used. (4) It is co-polymer. (a) 1,2 (b) 2,3 (c) \(1,2,3\) (d) \(1,2,3,4\)

Polymethyl methacrylate (PMMA) is a transparent thermoplastic often used as a lighter, more shatter-resistant alternative to glass. This synthetic polymer is known for its clarity and is also commonly referred to as acrylic, acrylic glass, or by brand names such as Plexiglas.

PMMA's transparency and durability make it suitable for a wide range of applications, including aircraft windows, aquariums, and protective barriers. One of the properties that contributes to its popularity is its resistance to UV light and weathering, which allows for its use in outdoor environments without significant degradation.

When examining PMMA, it's important to note that it's not only used for its physical properties but also for the ease with which it can be fabricated. It can be cut, drilled, and polished, and it softens enough when heated to be molded into various shapes, which returns us to its classification as a thermoplastic, a type of material that becomes pliable at certain elevated temperatures and can be shaped.

Thermoplastics are a class of polymers that become moldable above a specific temperature and solidify upon cooling. Unlike thermosetting plastics, which form irreversible chemical bonds during curing, thermoplastics can be remelted and remolded multiple times without altering their fundamental chemical structure. This property stems from the way the polymer chains interact.

PMMA falls under this category due to its ability to soften when heated and harden when cooled. This characteristic makes thermoplastics very versatile and recyclable, as they can be reprocessed without undergoing significant chemical changes. In addition, thermoplastics like PMMA are often favored in manufacturing for their ease of injection molding, extrusion, and thermoforming.

The polymerization process is the chemical reaction in which monomer molecules join together to form polymer chains. There are several types of polymerization, but the relevant type for PMMA is free radical polymerization.

This process starts with an initiator, typically an organic peroxide, which decomposes to form free radicals under heat or light. Once these highly reactive atoms are formed, they attack the double bond in the monomer molecule—in the case of PMMA, the monomer is methyl methacrylate. The monomers then link together in a chain reaction, creating long, repeating units that make up the polymer.

Free radical polymerization requires careful control of temperature, pressure, and reaction time to achieve the desired molecular weight and properties of the polymer. When manufacturing PMMA, precise control over these variables ensures a product with optimal strength, clarity, and stability.