1.1 Types of Polymers 3 Fig.1.2 Possible M-A-A-A-A-A-A-A-A -A-B-B-A-B-A-A-B-W arrangements of repeating units to form different type Homopolymer Random copolymer polymers -A-B-A-B-A-B-A-B- M-A-A-A-A-B-B-B-B- Alternating copolymer Block copolymer M-A-A-A-A-A-A-A-AW B-B-B-B-B-B- Graft copolymer 1.1 Types of Polymers There are many different types of polymers that can be differentiated from the arrangement of repeating units,and the different arrangements of molecular seg- ment [3].A polymer prepared from one kind of monomer is called homopolymer. A polymer prepared from more than one kind of monomer is called copolymer, including random copolymer,alternating copolymer,block copolymer,and graft copolymer(Fig.1.2).These homopolymer and copolymers also can be prepared into polymers with different arrangement of molecular segment,such as star polymer,comb polymer,ladder polymer,dendrimer,and so on.(Fig.1.3). 1.2 Types of Polymerization The types of polymerizations are generally classified into chain polymerization and step polymerization according to chemical reactions in the polymerization [4]. The molecular weight of polymers can be built either gradually by step reactions or simultaneously by chain reaction depending on the chemical structure of the monomer.For the step polymerization,the monomers need to have bifunctional groups to link 1 molecule at one time.If the bifunctional groups are the same such as ethylene glycol(OH-CH2CH2-OH),one will need different type of bifunctional monomer such as terephthalic acid(COOH-CH4-COOH)to synthesize polyester [-CH2-CH2-O-C(=O)CHC(=O)O-]at relative high temperature to remove water.This type of polymerization is also called polycondensation polymerization due to the loss of molecule during the polymerization. The monomers containing double bond can be polymerized by chain reaction. The polymerization proceeds by three steps of initiation,propagation,and termi- nation.Depending on the type of initiation,the chain polymerization can be classified into free radical chain polymerization,ionic chain polymerization,and
1.1 Types of Polymers There are many different types of polymers that can be differentiated from the arrangement of repeating units, and the different arrangements of molecular segment [3]. A polymer prepared from one kind of monomer is called homopolymer. A polymer prepared from more than one kind of monomer is called copolymer, including random copolymer, alternating copolymer, block copolymer, and graft copolymer (Fig. 1.2). These homopolymer and copolymers also can be prepared into polymers with different arrangement of molecular segment, such as star polymer, comb polymer, ladder polymer, dendrimer, and so on. (Fig. 1.3). 1.2 Types of Polymerization The types of polymerizations are generally classified into chain polymerization and step polymerization according to chemical reactions in the polymerization [4]. The molecular weight of polymers can be built either gradually by step reactions or simultaneously by chain reaction depending on the chemical structure of the monomer. For the step polymerization, the monomers need to have bifunctional groups to link 1 molecule at one time. If the bifunctional groups are the same such as ethylene glycol (OH–CH2CH2–OH), one will need different type of bifunctional monomer such as terephthalic acid (COOH–C6H4–COOH) to synthesize polyester [–CH2–CH2–O–C(=O)C6H4C(=O)O–]n at relative high temperature to remove water. This type of polymerization is also called polycondensation polymerization due to the loss of molecule during the polymerization. The monomers containing double bond can be polymerized by chain reaction. The polymerization proceeds by three steps of initiation, propagation, and termination. Depending on the type of initiation, the chain polymerization can be classified into free radical chain polymerization, ionic chain polymerization, and Fig. 1.2 Possible arrangements of repeating units to form different type polymers 1.1 Types of Polymers 3
I Introduction (d) (e) (f) (g) (h) () Fig.1.3 Possible arrangements of molecular segment to form different type polymers:(a)linear polymer,(b)branched polymer,(c)crosslinked polymer,(d)star polymer,(e)comb polymer, (f)ladder polymer,(g)polyrotaxane,(h)polycatenane,(i)dendrimer coordinating chain polymerization.Their principles will be addressed in the subsequent chapters.Copolymers are made from more than one kind of monomer to meet balanced properties required in many different applications.The differ- ences in the reactivity of different monomer and growing polymer chain need to be considered in the synthesis of copolymer.We will also discuss this subject in the later chapter. Ring opening polymerization has been extensively used in synthesis of poly- ether,polyamide,polysiloxane,and the curing of the epoxy resin.The reaction mechanism of ring opening polymerization is unique in its own way which shows a combination behavior of step polymerization and chain polymerization.The detailed reaction mechanism will be present in the last chapter of this book 1.3 Nomenclature of Polymers The nomenclature of polymers [1,3]is usually based on the source of monomer, for example,poly(vinyl chloride)-(CH2CHCI)-is made from vinyl chloride monomer,and poly(&-caprolacton)-[NH-CO-(CH2)s]-,that is the same as poly (6-aminocaproic acid),is made from E-caprolacton.Many polymers commonly are named basis on their structures such as poly(hexamethylene sebacamide)-[HN- (CH2)-NHCO-(CH2)s-CO]-,poly(ethylene terephthalate)-[O-CH2CH2-O- CO-C6Hs-CO],and poly(trimethylene ethylene urethane)-[O-CH2CH2CH2- O-CO-NH-CH2-CH2-NH-COl-
coordinating chain polymerization. Their principles will be addressed in the subsequent chapters. Copolymers are made from more than one kind of monomer to meet balanced properties required in many different applications. The differences in the reactivity of different monomer and growing polymer chain need to be considered in the synthesis of copolymer. We will also discuss this subject in the later chapter. Ring opening polymerization has been extensively used in synthesis of polyether, polyamide, polysiloxane, and the curing of the epoxy resin. The reaction mechanism of ring opening polymerization is unique in its own way which shows a combination behavior of step polymerization and chain polymerization. The detailed reaction mechanism will be present in the last chapter of this book. 1.3 Nomenclature of Polymers The nomenclature of polymers [1, 3] is usually based on the source of monomer, for example, poly(vinyl chloride) –(CH2CHCl)n– is made from vinyl chloride monomer, and poly(e-caprolacton) –[NH–CO–(CH2)5]n–, that is the same as poly (6-aminocaproic acid), is made from e-caprolacton. Many polymers commonly are named basis on their structures such as poly (hexamethylene sebacamide) –[HN– (CH2)6–NHCO–(CH2)8–CO]n–, poly(ethylene terephthalate) –[O–CH2CH2–O– CO–C6H5–CO]n–, and poly(trimethylene ethylene urethane) –[O–CH2CH2CH2– O–CO–NH–CH2–CH2–NH–CO]n–. Fig. 1.3 Possible arrangements of molecular segment to form different type polymers: (a) linear polymer, (b) branched polymer, (c) crosslinked polymer, (d) star polymer, (e) comb polymer, (f) ladder polymer, (g) polyrotaxane, (h) polycatenane, (i) dendrimer 4 1 Introduction
1.3 Nomenclature of Polymers 5 Table 1.1 Comparison between common name and IUPAC name of polymers Structure Common name IUPAC name -(CH2-CH2) polyethylene poly(methylene) -(CH(CH3)-CH2)- polypropylene poly(propylene) -CH(C.Hs)-CH2)- polystyrene poly(1-phenyl ethylene) The International Union of Pure and Applied Chemistry (IUPAC)polymer nomenclature system is a more systematic approach.The basis of the IUPAC polymer nomenclature system is the selection of a preferred CRU(constitutional repeating unit),i.e.,structural repeating unit,as tabulated in Table 1.1.The name is made according to the seniority among the atoms or subunits making up the CRU.The steps including (1)CRU is identified,(2)substituent groups on the backbone are assigned the lowest possible number,and(3)the name is placed in parentheses and prefixed with poly. For the copolymers,they are named according to the arrangements of the repeating units in copolymers.For example,for a copolymer that consists of polystyrene and poly(methyl methacrylate),this copolymer can be abbreviated as either poly[styrene-co-(methyl methacrylate)]or copoly(styrene/methyl methac- rylate).For an alternating copolymer,an abbreviation of alt can be placed between these two homopolymers,as poly[styrene-alt-(methyl methacrylate)].Therefore, the alt is replaced by block and graft that can represent the block copolymer [polystyrene-block-poly(methyl methacrylate)]and graft copolymer [polystyrene- graft-poly(methyl methacrylate)],respectively. The source-based nomenclature system is still one of choices in the polymer community,although the important reference sources such as Chemical Abstracts and Polymer Handbook have adopted the IUPAC system.Polymers used in business for long time usually have their own trade name,due to sometimes a polymer named by IUPAC name is not read easily and too long to use 0-C-0十 Polycarbonate O ocn-o Epoxy Resin Fig.1.4 Chemical structures of polycarbonate and epoxy resin
The International Union of Pure and Applied Chemistry (IUPAC) polymer nomenclature system is a more systematic approach. The basis of the IUPAC polymer nomenclature system is the selection of a preferred CRU (constitutional repeating unit), i.e., structural repeating unit, as tabulated in Table 1.1. The name is made according to the seniority among the atoms or subunits making up the CRU. The steps including (1) CRU is identified, (2) substituent groups on the backbone are assigned the lowest possible number, and (3) the name is placed in parentheses and prefixed with poly. For the copolymers, they are named according to the arrangements of the repeating units in copolymers. For example, for a copolymer that consists of polystyrene and poly(methyl methacrylate), this copolymer can be abbreviated as either poly[styrene-co-(methyl methacrylate)] or copoly(styrene/methyl methacrylate). For an alternating copolymer, an abbreviation of alt can be placed between these two homopolymers, as poly[styrene-alt-(methyl methacrylate)]. Therefore, the alt is replaced by block and graft that can represent the block copolymer [polystyrene-block-poly(methyl methacrylate)] and graft copolymer [polystyrenegraft-poly(methyl methacrylate)], respectively. The source-based nomenclature system is still one of choices in the polymer community, although the important reference sources such as Chemical Abstracts and Polymer Handbook have adopted the IUPAC system. Polymers used in business for long time usually have their own trade name, due to sometimes a polymer named by IUPAC name is not read easily and too long to use Table 1.1 Comparison between common name and IUPAC name of polymers Structure Common name IUPAC name –(CH2–CH2)– polyethylene poly(methylene) –(CH(CH3)–CH2)– polypropylene poly(propylene) –(CH(C6H5)–CH2)– polystyrene poly(1-phenyl ethylene) C CH3 CH3 O C O O n Polycarbonate Epoxy Resin H2C O CH CH2O C CH3 CH3 OCH2 CHCH2O OH n C CH3 CH3 OCH2 CH O CH2 Fig. 1.4 Chemical structures of polycarbonate and epoxy resin 1.3 Nomenclature of Polymers 5
6 I Introduction Table 1.2 Representative polymers used in modern society Common name Abbreviation Chemical structure Polyethylene PE CHCH Polypropylene PP FCH2CH-1 CH3n Poly(vinyl chloride) PVC CH2CH- Poly(ethylene terephthalate) PET coo-8-8-o0 Polystyrene PS CH2CH Phenol-formaldehyde none OH Polyisoprene PI -H2C、 CH2 C=( HaC Polyacrylonitrile PAN CH2CH- CN Poly(vinyl acetate) PVA CH2CH- O-C-CH3 Poly(methyl methacrylate) PMMA CH3 CH2C- -O-CHa Polycaprolactam Nylon 6 NHCH2sC Polycarbonate PC Poly(3-hexyl thiophene) P3HT
Table 1.2 Representative polymers used in modern society Common name Abbreviation Chemical structure Polyethylene PE CH2CH2 n Polypropylene PP CH2CH CH3 n Poly(vinyl chloride) PVC CH2CH Cl n Poly(ethylene terephthalate) PET CH2CH2 O C O C O O n Polystyrene PS CH2CH n Phenol–formaldehyde none OH CH2 n Polyisoprene PI C C H2C H3C CH2 H n Polyacrylonitrile PAN CH2CH n CN Poly(vinyl acetate) PVA CH2CH O C O CH3 n Poly(methyl methacrylate) PMMA CH2C C O O n CH3 CH3 Polycaprolactam Nylon 6 NH(CH2)5 C O n Polycarbonate PC O C CH3 CH3 C O O n Poly(3-hexyl thiophene) P3HT S C6H13 n 6 1 Introduction
1.3 Nomenclature of Polymers 1 Table 1.3 Recycling codes of plastics [3] Number Letters Plastic PET Poly(ethylene terephthalate) 2 HDPE High density polyethylene 3 V or PVC Poly(vinyl chloride) x LDPE Low density polyethylene 5 PP Polypropylene 6 PS Polystyrene 7 OTHER Others or mixed plastics conveniently.For example,IUPAC name for polycarbonate is poly(oxy carbonyl oxy-1,4-phenylene-isopropylidene-1,4-phenylene)and the repeating unit is-[O- CO-O-C6H4-C(CH3)2-C6H4]-.Bisphenol A epoxy resin has an IUPAC name of 4,4'-dimethoxy oxirane -2,2-diphenyl propane.Figure 1.4 shows the chemical structures of polycarbonate and bisphenol A epoxy resin. Table 1.2 organizes some representative polymers in modern society with their common name,abbreviation,and chemical structure according to the amount of usage.Their synthesis and properties will be discussed throughout this text book. The abbreviated name of polymer has been adapted for subsequent chapter for simplicity. 1.4 Polymer Recycling Polymer recycling [3]is an important matter being carried out worldwide to reduce pollution and conserve material.Poly(ethylene terephthalate)(PET)and high density polyethylene (HDPE)share more than 70%of the demand for recycled plastics.The recycling industry sometime encounters economic diffi- culties because most "virgin"plastics are not only of better quality than their recycled counterparts,but are often less expensive.In Taiwan,the majority of used plastics are burned as fuel or pyrolyzed to make fuel.The Society of the Plastics Industry (SPI)of USA has adopted plastic recycling codes to be used interna- tionally as shown in Table 1.3,so the recycled polymers can be sorted according to their code before they are used as raw materials for specific applications. 1.5 Problems 1.Write a concise definition of each term listed below,using examples as appropriate,(a)polymer,(b)monomer,(c)functional group,(d)oligomer,(e) telechelic polymer,(f)degree of polymerization,(g)molecular weight distri- bution,(o)copolymer,(p)chain polymerization,(q)step polymerization
conveniently. For example, IUPAC name for polycarbonate is poly(oxy carbonyl oxy -1,4-phenylene-isopropylidene -1,4-phenylene) and the repeating unit is –[O– CO–O–C6H4–C(CH3)2–C6H4]n–. Bisphenol A epoxy resin has an IUPAC name of 4,40 -dimethoxy oxirane -2,2-diphenyl propane. Figure 1.4 shows the chemical structures of polycarbonate and bisphenol A epoxy resin. Table 1.2 organizes some representative polymers in modern society with their common name, abbreviation, and chemical structure according to the amount of usage. Their synthesis and properties will be discussed throughout this text book. The abbreviated name of polymer has been adapted for subsequent chapter for simplicity. 1.4 Polymer Recycling Polymer recycling [3] is an important matter being carried out worldwide to reduce pollution and conserve material. Poly(ethylene terephthalate) (PET) and high density polyethylene (HDPE) share more than 70 % of the demand for recycled plastics. The recycling industry sometime encounters economic diffi- culties because most ‘‘virgin’’ plastics are not only of better quality than their recycled counterparts, but are often less expensive. In Taiwan, the majority of used plastics are burned as fuel or pyrolyzed to make fuel. The Society of the Plastics Industry (SPI) of USA has adopted plastic recycling codes to be used internationally as shown in Table 1.3, so the recycled polymers can be sorted according to their code before they are used as raw materials for specific applications. 1.5 Problems 1. Write a concise definition of each term listed below, using examples as appropriate, (a) polymer, (b) monomer, (c) functional group, (d) oligomer, (e) telechelic polymer, (f) degree of polymerization, (g) molecular weight distribution, (o) copolymer, (p) chain polymerization, (q) step polymerization. Table 1.3 Recycling codes of plastics [3] Number Letters Plastic 1 PET Poly(ethylene terephthalate) 2 HDPE High density polyethylene 3 V or PVC Poly(vinyl chloride) 4 LDPE Low density polyethylene 5 PP Polypropylene 6 PS Polystyrene 7 OTHER Others or mixed plastics 1.3 Nomenclature of Polymers 7