Materials Science/Polymers

Materials Science is a Division C event which tests knowledge of the properties and characteristics of various materials. For the 2018 season, the event will focus on polymers and plastics.

Organic Nomeclature
The most common system of naming organic compounds (hydrocarbons and derivative molecules) is the IUPAC system. You could also be tested on traditional names of some common compounds (such as styrene, vs. the IUPAC designation of ethenylbenzene), though this is less likely.

Parent Chain
The first step in naming an organic molecule is identifying the parent chain - a single continuous chain that forms the basis of the systematic IUPAC name. This typically also involves noting any functional groups and determining their precedence. The parent chain is determined by three characteristics, in order of precedence:
 * 1) the chain that contains the largest number of the highest precedence functional group.
 * 2) the chain that contains the most double/triple bonds.
 * 3) the longest chain.

Once the parent chain is determined, it is named based on its length. This forms the stem of the molecule's name.

Only the most common names are listed above.

For an alkane (an organic molecule with no double or triple bonds), "-ane" is appended to the end of the stem (if there is a suffix, append "-an"). Hence, a three-carbon chain (with the requisite hydrogen atoms attached) would be "propane".

The parent chain is numbered by assigning location numbers along the chain in both directions, and choosing a direction based on which one minimizes the lowest location number of:
 * 1) suffix functional groups (i.e. whichever attached functional group type has the highest precedence)
 * 2) multiple bonds
 * 3) prefixes (i.e. both functional groups and side chains)

Substituents are attached to the stem as either prefixes or a suffix, and with associated location numbers. Most functional groups can be attached as either prefixes or suffixes - the highest-precedence of these will be the suffix, and the rest will be prefixes. Side chains and halogens are attached as suffixes.

Multiple Bonds
Double and triple bonds are identified by their first location when counting along the direction of numbering. For example, a 4-carbon chain with a double bond joining the second and third carbons would have a double bond at position 2. Double and triple bonds are denoted by adding "-ene" or "-yne" to the stem instead of "-ane", with the position number. For example, the previously described molecule would be "buta-2-ene", with the "a" after the stem for pronunciation purposes.

Although double and triple bonds are used as suffixes, they do not count as such suffix when evaluating functional groups. A stem can have both a multiple bond suffix and a functional group suffix (with the latter being attached after the former).

Side chains
Side chains are hydrocarbons that branch off of the parent chain. They are named similarly to the parent chain except with -yl: methyl, ethyl, propyl, etc.

They are identified by their location. For example, a propyl at position 3 would be "3-propyl", with a dash used to separate the components. If there are multiple side chains of the same length, use commas, and pre-prefixes (di-, tri-, tetra-, etc.). For example, if there are two ethyls at position 3 and one ethyl at position four, they would be collectively identified as "3,3,4-triethyl".

Functional Groups
Functional groups are parts of a molecule (moeities) that typically have unique chemical properties and affect the way an organic molecule behaves. They are attached to the parent carbon chain, or inserted in between the parent chain and a side chain, and are identified by their number (they can be attached to side chains as well, but the nomenclature for that is complicated and unlikely to show up in competitions). Functional groups also have an order of precedence. The type of functional group in a molecule with the highest precedence will be used in suffix form, while the rest will be used in prefix form.

Functional groups allowed under the 2018 rules are listed below, in order of precedence. "R" refers to an arbitrary section of the molecule (in the usage below, excluding a single hydrogen). The prefixes for most higher-precedence groups are rarely used, since test questions are unlikely to include many different types of functional groups.
 * 1 This is unlikely to be used, since the rules don't include any functional groups with higher precedence.
 * 2 can't find general form including R-groups

Putting it Together


Aromatics
An aromatic is a derivative of benzene. Nomenclature for aromatics quickly becomes complicated, so you will likely only see simpler aromatics on tests.

Linear vs. Branched
Linear polymer chains are continuously attached monomers in a line. A branched polymer contains chains that attach to the side of existing chains via replacement of a hydrogen. When chain attach on both ends, this is cross-linking, which is what produces thermoset polymers.

Entanglement
Entanglement is the process by which a polymer transfers stress from one part of the chain to the entire object. It is less of a physical entanglement and more a chemical process of attractive forces between different parts of the chain.

Network Polymers
Network polymers typically have three or four connections per monomer, and are arranged in two or three dimensions without much linear structure.