TY - JOUR

T1 - Molecular exchange in spherical diblock copolymer colloids synthesised by polymerisation-induced self-assembly

AU - Smith, Gregory N.

AU - Grillo, Isabelle

AU - Hallett, James E.

PY - 2020/6/15

Y1 - 2020/6/15

N2 - Hypothesis To study molecular exchange between colloids requires the preparation of suitably labelled species. Deuterium isotopic labelling has been used to prepare two chemically identical yet isotopically distinguishable poly(lauryl methacrylate)–poly(methyl methacrylate) (PLMA–PMMA) diblock copolymer colloids by polymerisation-induced self-assembly (PISA) directly in an alkane solvent. Molecular exchange should be detectable by performing small-angle neutron scattering (SANS) measurements on the dispersions.Experiments SANS measurements were performed on fully hydrogenous PLMA39–PMMA57 and deuterated core PLMA39–P(MMA-d8)57 colloids. They were mixed in equal amounts and heated to determine if molecular exchange occurred. PISA syntheses are often thermally initiated, and diblock copolymers self-assemble at elevated temperature, making this an important parameter to study. Experimental data for the mixture were compared to predicted curves for exchanged and non-exchanged colloids.Findings The scattering of a mixture of fully hydrogenous and deuterated core copolymers does not disappear upon molecular exchange, due to the remaining contrast between the stabiliser and the core and solvent even after the cores fully exchange. By simultaneously fitting the SANS data from dispersions before mixing and using these parameters to constrain fitting the SANS data of mixtures, the molecular exchange between diblock copolymer micelles upon heating is clearly observed.

AB - Hypothesis To study molecular exchange between colloids requires the preparation of suitably labelled species. Deuterium isotopic labelling has been used to prepare two chemically identical yet isotopically distinguishable poly(lauryl methacrylate)–poly(methyl methacrylate) (PLMA–PMMA) diblock copolymer colloids by polymerisation-induced self-assembly (PISA) directly in an alkane solvent. Molecular exchange should be detectable by performing small-angle neutron scattering (SANS) measurements on the dispersions.Experiments SANS measurements were performed on fully hydrogenous PLMA39–PMMA57 and deuterated core PLMA39–P(MMA-d8)57 colloids. They were mixed in equal amounts and heated to determine if molecular exchange occurred. PISA syntheses are often thermally initiated, and diblock copolymers self-assemble at elevated temperature, making this an important parameter to study. Experimental data for the mixture were compared to predicted curves for exchanged and non-exchanged colloids.Findings The scattering of a mixture of fully hydrogenous and deuterated core copolymers does not disappear upon molecular exchange, due to the remaining contrast between the stabiliser and the core and solvent even after the cores fully exchange. By simultaneously fitting the SANS data from dispersions before mixing and using these parameters to constrain fitting the SANS data of mixtures, the molecular exchange between diblock copolymer micelles upon heating is clearly observed.

KW - Colloids

KW - Small-angle neutron scattering

KW - Molecular exchange

KW - Polymer micelles

KW - Polymerisation-induced self-assembly

U2 - 10.1016/j.jcis.2020.06.022

DO - 10.1016/j.jcis.2020.06.022

M3 - Journal article

C2 - 32592989

VL - 579

SP - 243

EP - 249

JO - Journal of Colloid and Interface Science

JF - Journal of Colloid and Interface Science

SN - 0021-9797

ER -